Bug Summary

File:src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Support/GenericDomTree.h
Warning:line 494, column 12
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -cc1 -triple amd64-unknown-openbsd7.0 -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name MachineSink.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model pic -pic-level 1 -fhalf-no-semantic-interposition -mframe-pointer=all -relaxed-aliasing -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/usr/src/gnu/usr.bin/clang/libLLVM/obj -resource-dir /usr/local/lib/clang/13.0.0 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Analysis -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ASMParser -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/BinaryFormat -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Bitcode -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Bitcode -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Bitstream -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /include/llvm/CodeGen -I /include/llvm/CodeGen/PBQP -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/IR -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/IR -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Coroutines -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ProfileData/Coverage -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/CodeView -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/DWARF -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/MSF -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/PDB -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Demangle -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ExecutionEngine -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ExecutionEngine/JITLink -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ExecutionEngine/Orc -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend/OpenACC -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend/OpenMP -I /include/llvm/CodeGen/GlobalISel -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/IRReader -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/InstCombine -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/Transforms/InstCombine -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/LTO -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Linker -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/MC -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/MC/MCParser -I /include/llvm/CodeGen/MIRParser -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Object -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Option -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Passes -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ProfileData -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Scalar -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ADT -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Support -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/Symbolize -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Target -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Utils -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Vectorize -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/IPO -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include -I /usr/src/gnu/usr.bin/clang/libLLVM/../include -I /usr/src/gnu/usr.bin/clang/libLLVM/obj -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include -D NDEBUG -D __STDC_LIMIT_MACROS -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D LLVM_PREFIX="/usr" -D PIC -internal-isystem /usr/include/c++/v1 -internal-isystem /usr/local/lib/clang/13.0.0/include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/usr/src/gnu/usr.bin/clang/libLLVM/obj -ferror-limit 19 -fvisibility-inlines-hidden -fwrapv -D_RET_PROTECTOR -ret-protector -fno-rtti -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-valloc -fno-builtin-free -fno-builtin-strdup -fno-builtin-strndup -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /home/ben/Projects/vmm/scan-build/2022-01-12-194120-40624-1 -x c++ /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/CodeGen/MachineSink.cpp

/usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/CodeGen/MachineSink.cpp

1//===- MachineSink.cpp - Sinking for machine instructions -----------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This pass moves instructions into successor blocks when possible, so that
10// they aren't executed on paths where their results aren't needed.
11//
12// This pass is not intended to be a replacement or a complete alternative
13// for an LLVM-IR-level sinking pass. It is only designed to sink simple
14// constructs that are not exposed before lowering and instruction selection.
15//
16//===----------------------------------------------------------------------===//
17
18#include "llvm/ADT/DenseSet.h"
19#include "llvm/ADT/MapVector.h"
20#include "llvm/ADT/PointerIntPair.h"
21#include "llvm/ADT/SetVector.h"
22#include "llvm/ADT/SmallSet.h"
23#include "llvm/ADT/SmallVector.h"
24#include "llvm/ADT/SparseBitVector.h"
25#include "llvm/ADT/Statistic.h"
26#include "llvm/Analysis/AliasAnalysis.h"
27#include "llvm/CodeGen/MachineBasicBlock.h"
28#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
29#include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
30#include "llvm/CodeGen/MachineDominators.h"
31#include "llvm/CodeGen/MachineFunction.h"
32#include "llvm/CodeGen/MachineFunctionPass.h"
33#include "llvm/CodeGen/MachineInstr.h"
34#include "llvm/CodeGen/MachineLoopInfo.h"
35#include "llvm/CodeGen/MachineOperand.h"
36#include "llvm/CodeGen/MachinePostDominators.h"
37#include "llvm/CodeGen/MachineRegisterInfo.h"
38#include "llvm/CodeGen/RegisterClassInfo.h"
39#include "llvm/CodeGen/RegisterPressure.h"
40#include "llvm/CodeGen/TargetInstrInfo.h"
41#include "llvm/CodeGen/TargetRegisterInfo.h"
42#include "llvm/CodeGen/TargetSubtargetInfo.h"
43#include "llvm/IR/BasicBlock.h"
44#include "llvm/IR/DebugInfoMetadata.h"
45#include "llvm/IR/LLVMContext.h"
46#include "llvm/InitializePasses.h"
47#include "llvm/MC/MCRegisterInfo.h"
48#include "llvm/Pass.h"
49#include "llvm/Support/BranchProbability.h"
50#include "llvm/Support/CommandLine.h"
51#include "llvm/Support/Debug.h"
52#include "llvm/Support/raw_ostream.h"
53#include <algorithm>
54#include <cassert>
55#include <cstdint>
56#include <map>
57#include <utility>
58#include <vector>
59
60using namespace llvm;
61
62#define DEBUG_TYPE"machine-sink" "machine-sink"
63
64static cl::opt<bool>
65SplitEdges("machine-sink-split",
66 cl::desc("Split critical edges during machine sinking"),
67 cl::init(true), cl::Hidden);
68
69static cl::opt<bool>
70UseBlockFreqInfo("machine-sink-bfi",
71 cl::desc("Use block frequency info to find successors to sink"),
72 cl::init(true), cl::Hidden);
73
74static cl::opt<unsigned> SplitEdgeProbabilityThreshold(
75 "machine-sink-split-probability-threshold",
76 cl::desc(
77 "Percentage threshold for splitting single-instruction critical edge. "
78 "If the branch threshold is higher than this threshold, we allow "
79 "speculative execution of up to 1 instruction to avoid branching to "
80 "splitted critical edge"),
81 cl::init(40), cl::Hidden);
82
83static cl::opt<unsigned> SinkLoadInstsPerBlockThreshold(
84 "machine-sink-load-instrs-threshold",
85 cl::desc("Do not try to find alias store for a load if there is a in-path "
86 "block whose instruction number is higher than this threshold."),
87 cl::init(2000), cl::Hidden);
88
89static cl::opt<unsigned> SinkLoadBlocksThreshold(
90 "machine-sink-load-blocks-threshold",
91 cl::desc("Do not try to find alias store for a load if the block number in "
92 "the straight line is higher than this threshold."),
93 cl::init(20), cl::Hidden);
94
95static cl::opt<bool>
96SinkInstsIntoLoop("sink-insts-to-avoid-spills",
97 cl::desc("Sink instructions into loops to avoid "
98 "register spills"),
99 cl::init(false), cl::Hidden);
100
101static cl::opt<unsigned> SinkIntoLoopLimit(
102 "machine-sink-loop-limit",
103 cl::desc("The maximum number of instructions considered for loop sinking."),
104 cl::init(50), cl::Hidden);
105
106STATISTIC(NumSunk, "Number of machine instructions sunk")static llvm::Statistic NumSunk = {"machine-sink", "NumSunk", "Number of machine instructions sunk"
}
;
107STATISTIC(NumLoopSunk, "Number of machine instructions sunk into a loop")static llvm::Statistic NumLoopSunk = {"machine-sink", "NumLoopSunk"
, "Number of machine instructions sunk into a loop"}
;
108STATISTIC(NumSplit, "Number of critical edges split")static llvm::Statistic NumSplit = {"machine-sink", "NumSplit"
, "Number of critical edges split"}
;
109STATISTIC(NumCoalesces, "Number of copies coalesced")static llvm::Statistic NumCoalesces = {"machine-sink", "NumCoalesces"
, "Number of copies coalesced"}
;
110STATISTIC(NumPostRACopySink, "Number of copies sunk after RA")static llvm::Statistic NumPostRACopySink = {"machine-sink", "NumPostRACopySink"
, "Number of copies sunk after RA"}
;
111
112namespace {
113
114 class MachineSinking : public MachineFunctionPass {
115 const TargetInstrInfo *TII;
116 const TargetRegisterInfo *TRI;
117 MachineRegisterInfo *MRI; // Machine register information
118 MachineDominatorTree *DT; // Machine dominator tree
119 MachinePostDominatorTree *PDT; // Machine post dominator tree
120 MachineLoopInfo *LI;
121 MachineBlockFrequencyInfo *MBFI;
122 const MachineBranchProbabilityInfo *MBPI;
123 AliasAnalysis *AA;
124 RegisterClassInfo RegClassInfo;
125
126 // Remember which edges have been considered for breaking.
127 SmallSet<std::pair<MachineBasicBlock*, MachineBasicBlock*>, 8>
128 CEBCandidates;
129 // Remember which edges we are about to split.
130 // This is different from CEBCandidates since those edges
131 // will be split.
132 SetVector<std::pair<MachineBasicBlock *, MachineBasicBlock *>> ToSplit;
133
134 SparseBitVector<> RegsToClearKillFlags;
135
136 using AllSuccsCache =
137 std::map<MachineBasicBlock *, SmallVector<MachineBasicBlock *, 4>>;
138
139 /// DBG_VALUE pointer and flag. The flag is true if this DBG_VALUE is
140 /// post-dominated by another DBG_VALUE of the same variable location.
141 /// This is necessary to detect sequences such as:
142 /// %0 = someinst
143 /// DBG_VALUE %0, !123, !DIExpression()
144 /// %1 = anotherinst
145 /// DBG_VALUE %1, !123, !DIExpression()
146 /// Where if %0 were to sink, the DBG_VAUE should not sink with it, as that
147 /// would re-order assignments.
148 using SeenDbgUser = PointerIntPair<MachineInstr *, 1>;
149
150 /// Record of DBG_VALUE uses of vregs in a block, so that we can identify
151 /// debug instructions to sink.
152 SmallDenseMap<unsigned, TinyPtrVector<SeenDbgUser>> SeenDbgUsers;
153
154 /// Record of debug variables that have had their locations set in the
155 /// current block.
156 DenseSet<DebugVariable> SeenDbgVars;
157
158 std::map<std::pair<MachineBasicBlock *, MachineBasicBlock *>, bool>
159 HasStoreCache;
160 std::map<std::pair<MachineBasicBlock *, MachineBasicBlock *>,
161 std::vector<MachineInstr *>>
162 StoreInstrCache;
163
164 /// Cached BB's register pressure.
165 std::map<MachineBasicBlock *, std::vector<unsigned>> CachedRegisterPressure;
166
167 public:
168 static char ID; // Pass identification
169
170 MachineSinking() : MachineFunctionPass(ID) {
171 initializeMachineSinkingPass(*PassRegistry::getPassRegistry());
172 }
173
174 bool runOnMachineFunction(MachineFunction &MF) override;
175
176 void getAnalysisUsage(AnalysisUsage &AU) const override {
177 MachineFunctionPass::getAnalysisUsage(AU);
178 AU.addRequired<AAResultsWrapperPass>();
179 AU.addRequired<MachineDominatorTree>();
180 AU.addRequired<MachinePostDominatorTree>();
181 AU.addRequired<MachineLoopInfo>();
182 AU.addRequired<MachineBranchProbabilityInfo>();
183 AU.addPreserved<MachineLoopInfo>();
184 if (UseBlockFreqInfo)
185 AU.addRequired<MachineBlockFrequencyInfo>();
186 }
187
188 void releaseMemory() override {
189 CEBCandidates.clear();
190 }
191
192 private:
193 bool ProcessBlock(MachineBasicBlock &MBB);
194 void ProcessDbgInst(MachineInstr &MI);
195 bool isWorthBreakingCriticalEdge(MachineInstr &MI,
196 MachineBasicBlock *From,
197 MachineBasicBlock *To);
198
199 bool hasStoreBetween(MachineBasicBlock *From, MachineBasicBlock *To,
200 MachineInstr &MI);
201
202 /// Postpone the splitting of the given critical
203 /// edge (\p From, \p To).
204 ///
205 /// We do not split the edges on the fly. Indeed, this invalidates
206 /// the dominance information and thus triggers a lot of updates
207 /// of that information underneath.
208 /// Instead, we postpone all the splits after each iteration of
209 /// the main loop. That way, the information is at least valid
210 /// for the lifetime of an iteration.
211 ///
212 /// \return True if the edge is marked as toSplit, false otherwise.
213 /// False can be returned if, for instance, this is not profitable.
214 bool PostponeSplitCriticalEdge(MachineInstr &MI,
215 MachineBasicBlock *From,
216 MachineBasicBlock *To,
217 bool BreakPHIEdge);
218 bool SinkInstruction(MachineInstr &MI, bool &SawStore,
219 AllSuccsCache &AllSuccessors);
220
221 /// If we sink a COPY inst, some debug users of it's destination may no
222 /// longer be dominated by the COPY, and will eventually be dropped.
223 /// This is easily rectified by forwarding the non-dominated debug uses
224 /// to the copy source.
225 void SalvageUnsunkDebugUsersOfCopy(MachineInstr &,
226 MachineBasicBlock *TargetBlock);
227 bool AllUsesDominatedByBlock(Register Reg, MachineBasicBlock *MBB,
228 MachineBasicBlock *DefMBB, bool &BreakPHIEdge,
229 bool &LocalUse) const;
230 MachineBasicBlock *FindSuccToSinkTo(MachineInstr &MI, MachineBasicBlock *MBB,
231 bool &BreakPHIEdge, AllSuccsCache &AllSuccessors);
232
233 void FindLoopSinkCandidates(MachineLoop *L, MachineBasicBlock *BB,
234 SmallVectorImpl<MachineInstr *> &Candidates);
235 bool SinkIntoLoop(MachineLoop *L, MachineInstr &I);
236
237 bool isProfitableToSinkTo(Register Reg, MachineInstr &MI,
238 MachineBasicBlock *MBB,
239 MachineBasicBlock *SuccToSinkTo,
240 AllSuccsCache &AllSuccessors);
241
242 bool PerformTrivialForwardCoalescing(MachineInstr &MI,
243 MachineBasicBlock *MBB);
244
245 SmallVector<MachineBasicBlock *, 4> &
246 GetAllSortedSuccessors(MachineInstr &MI, MachineBasicBlock *MBB,
247 AllSuccsCache &AllSuccessors) const;
248
249 std::vector<unsigned> &getBBRegisterPressure(MachineBasicBlock &MBB);
250 };
251
252} // end anonymous namespace
253
254char MachineSinking::ID = 0;
255
256char &llvm::MachineSinkingID = MachineSinking::ID;
257
258INITIALIZE_PASS_BEGIN(MachineSinking, DEBUG_TYPE,static void *initializeMachineSinkingPassOnce(PassRegistry &
Registry) {
259 "Machine code sinking", false, false)static void *initializeMachineSinkingPassOnce(PassRegistry &
Registry) {
260INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo)initializeMachineBranchProbabilityInfoPass(Registry);
261INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)initializeMachineDominatorTreePass(Registry);
262INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)initializeMachineLoopInfoPass(Registry);
263INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)initializeAAResultsWrapperPassPass(Registry);
264INITIALIZE_PASS_END(MachineSinking, DEBUG_TYPE,PassInfo *PI = new PassInfo( "Machine code sinking", "machine-sink"
, &MachineSinking::ID, PassInfo::NormalCtor_t(callDefaultCtor
<MachineSinking>), false, false); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeMachineSinkingPassFlag
; void llvm::initializeMachineSinkingPass(PassRegistry &Registry
) { llvm::call_once(InitializeMachineSinkingPassFlag, initializeMachineSinkingPassOnce
, std::ref(Registry)); }
265 "Machine code sinking", false, false)PassInfo *PI = new PassInfo( "Machine code sinking", "machine-sink"
, &MachineSinking::ID, PassInfo::NormalCtor_t(callDefaultCtor
<MachineSinking>), false, false); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeMachineSinkingPassFlag
; void llvm::initializeMachineSinkingPass(PassRegistry &Registry
) { llvm::call_once(InitializeMachineSinkingPassFlag, initializeMachineSinkingPassOnce
, std::ref(Registry)); }
266
267bool MachineSinking::PerformTrivialForwardCoalescing(MachineInstr &MI,
268 MachineBasicBlock *MBB) {
269 if (!MI.isCopy())
270 return false;
271
272 Register SrcReg = MI.getOperand(1).getReg();
273 Register DstReg = MI.getOperand(0).getReg();
274 if (!Register::isVirtualRegister(SrcReg) ||
275 !Register::isVirtualRegister(DstReg) || !MRI->hasOneNonDBGUse(SrcReg))
276 return false;
277
278 const TargetRegisterClass *SRC = MRI->getRegClass(SrcReg);
279 const TargetRegisterClass *DRC = MRI->getRegClass(DstReg);
280 if (SRC != DRC)
281 return false;
282
283 MachineInstr *DefMI = MRI->getVRegDef(SrcReg);
284 if (DefMI->isCopyLike())
285 return false;
286 LLVM_DEBUG(dbgs() << "Coalescing: " << *DefMI)do { } while (false);
287 LLVM_DEBUG(dbgs() << "*** to: " << MI)do { } while (false);
288 MRI->replaceRegWith(DstReg, SrcReg);
289 MI.eraseFromParent();
290
291 // Conservatively, clear any kill flags, since it's possible that they are no
292 // longer correct.
293 MRI->clearKillFlags(SrcReg);
294
295 ++NumCoalesces;
296 return true;
297}
298
299/// AllUsesDominatedByBlock - Return true if all uses of the specified register
300/// occur in blocks dominated by the specified block. If any use is in the
301/// definition block, then return false since it is never legal to move def
302/// after uses.
303bool MachineSinking::AllUsesDominatedByBlock(Register Reg,
304 MachineBasicBlock *MBB,
305 MachineBasicBlock *DefMBB,
306 bool &BreakPHIEdge,
307 bool &LocalUse) const {
308 assert(Register::isVirtualRegister(Reg) && "Only makes sense for vregs")((void)0);
309
310 // Ignore debug uses because debug info doesn't affect the code.
311 if (MRI->use_nodbg_empty(Reg))
312 return true;
313
314 // BreakPHIEdge is true if all the uses are in the successor MBB being sunken
315 // into and they are all PHI nodes. In this case, machine-sink must break
316 // the critical edge first. e.g.
317 //
318 // %bb.1:
319 // Predecessors according to CFG: %bb.0
320 // ...
321 // %def = DEC64_32r %x, implicit-def dead %eflags
322 // ...
323 // JE_4 <%bb.37>, implicit %eflags
324 // Successors according to CFG: %bb.37 %bb.2
325 //
326 // %bb.2:
327 // %p = PHI %y, %bb.0, %def, %bb.1
328 if (all_of(MRI->use_nodbg_operands(Reg), [&](MachineOperand &MO) {
329 MachineInstr *UseInst = MO.getParent();
330 unsigned OpNo = UseInst->getOperandNo(&MO);
331 MachineBasicBlock *UseBlock = UseInst->getParent();
332 return UseBlock == MBB && UseInst->isPHI() &&
333 UseInst->getOperand(OpNo + 1).getMBB() == DefMBB;
334 })) {
335 BreakPHIEdge = true;
336 return true;
337 }
338
339 for (MachineOperand &MO : MRI->use_nodbg_operands(Reg)) {
340 // Determine the block of the use.
341 MachineInstr *UseInst = MO.getParent();
342 unsigned OpNo = &MO - &UseInst->getOperand(0);
343 MachineBasicBlock *UseBlock = UseInst->getParent();
344 if (UseInst->isPHI()) {
345 // PHI nodes use the operand in the predecessor block, not the block with
346 // the PHI.
347 UseBlock = UseInst->getOperand(OpNo+1).getMBB();
348 } else if (UseBlock == DefMBB) {
349 LocalUse = true;
350 return false;
351 }
352
353 // Check that it dominates.
354 if (!DT->dominates(MBB, UseBlock))
355 return false;
356 }
357
358 return true;
359}
360
361/// Return true if this machine instruction loads from global offset table or
362/// constant pool.
363static bool mayLoadFromGOTOrConstantPool(MachineInstr &MI) {
364 assert(MI.mayLoad() && "Expected MI that loads!")((void)0);
365
366 // If we lost memory operands, conservatively assume that the instruction
367 // reads from everything..
368 if (MI.memoperands_empty())
369 return true;
370
371 for (MachineMemOperand *MemOp : MI.memoperands())
372 if (const PseudoSourceValue *PSV = MemOp->getPseudoValue())
373 if (PSV->isGOT() || PSV->isConstantPool())
374 return true;
375
376 return false;
377}
378
379void MachineSinking::FindLoopSinkCandidates(MachineLoop *L, MachineBasicBlock *BB,
380 SmallVectorImpl<MachineInstr *> &Candidates) {
381 for (auto &MI : *BB) {
382 LLVM_DEBUG(dbgs() << "LoopSink: Analysing candidate: " << MI)do { } while (false);
383 if (!TII->shouldSink(MI)) {
384 LLVM_DEBUG(dbgs() << "LoopSink: Instruction not a candidate for this "do { } while (false)
385 "target\n")do { } while (false);
386 continue;
387 }
388 if (!L->isLoopInvariant(MI)) {
389 LLVM_DEBUG(dbgs() << "LoopSink: Instruction is not loop invariant\n")do { } while (false);
390 continue;
391 }
392 bool DontMoveAcrossStore = true;
393 if (!MI.isSafeToMove(AA, DontMoveAcrossStore)) {
394 LLVM_DEBUG(dbgs() << "LoopSink: Instruction not safe to move.\n")do { } while (false);
395 continue;
396 }
397 if (MI.mayLoad() && !mayLoadFromGOTOrConstantPool(MI)) {
398 LLVM_DEBUG(dbgs() << "LoopSink: Dont sink GOT or constant pool loads\n")do { } while (false);
399 continue;
400 }
401 if (MI.isConvergent())
402 continue;
403
404 const MachineOperand &MO = MI.getOperand(0);
405 if (!MO.isReg() || !MO.getReg() || !MO.isDef())
406 continue;
407 if (!MRI->hasOneDef(MO.getReg()))
408 continue;
409
410 LLVM_DEBUG(dbgs() << "LoopSink: Instruction added as candidate.\n")do { } while (false);
411 Candidates.push_back(&MI);
412 }
413}
414
415bool MachineSinking::runOnMachineFunction(MachineFunction &MF) {
416 if (skipFunction(MF.getFunction()))
1
Assuming the condition is false
2
Taking false branch
417 return false;
418
419 LLVM_DEBUG(dbgs() << "******** Machine Sinking ********\n")do { } while (false);
3
Loop condition is false. Exiting loop
420
421 TII = MF.getSubtarget().getInstrInfo();
422 TRI = MF.getSubtarget().getRegisterInfo();
423 MRI = &MF.getRegInfo();
424 DT = &getAnalysis<MachineDominatorTree>();
425 PDT = &getAnalysis<MachinePostDominatorTree>();
426 LI = &getAnalysis<MachineLoopInfo>();
427 MBFI = UseBlockFreqInfo ? &getAnalysis<MachineBlockFrequencyInfo>() : nullptr;
4
Assuming the condition is false
5
'?' condition is false
428 MBPI = &getAnalysis<MachineBranchProbabilityInfo>();
429 AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
430 RegClassInfo.runOnMachineFunction(MF);
431
432 bool EverMadeChange = false;
433
434 while (true) {
6
Loop condition is true. Entering loop body
435 bool MadeChange = false;
436
437 // Process all basic blocks.
438 CEBCandidates.clear();
439 ToSplit.clear();
440 for (auto &MBB: MF)
441 MadeChange |= ProcessBlock(MBB);
442
443 // If we have anything we marked as toSplit, split it now.
444 for (auto &Pair : ToSplit) {
445 auto NewSucc = Pair.first->SplitCriticalEdge(Pair.second, *this);
446 if (NewSucc != nullptr) {
447 LLVM_DEBUG(dbgs() << " *** Splitting critical edge: "do { } while (false)
448 << printMBBReference(*Pair.first) << " -- "do { } while (false)
449 << printMBBReference(*NewSucc) << " -- "do { } while (false)
450 << printMBBReference(*Pair.second) << '\n')do { } while (false);
451 if (MBFI)
452 MBFI->onEdgeSplit(*Pair.first, *NewSucc, *MBPI);
453
454 MadeChange = true;
455 ++NumSplit;
456 } else
457 LLVM_DEBUG(dbgs() << " *** Not legal to break critical edge\n")do { } while (false);
458 }
459 // If this iteration over the code changed anything, keep iterating.
460 if (!MadeChange
6.1
'MadeChange' is false
6.1
'MadeChange' is false
6.1
'MadeChange' is false
6.1
'MadeChange' is false
) break;
7
Taking true branch
8
Execution continues on line 464
461 EverMadeChange = true;
462 }
463
464 if (SinkInstsIntoLoop) {
9
Assuming the condition is true
10
Taking true branch
465 SmallVector<MachineLoop *, 8> Loops(LI->begin(), LI->end());
466 for (auto *L : Loops) {
11
Assuming '__begin2' is not equal to '__end2'
467 MachineBasicBlock *Preheader = LI->findLoopPreheader(L);
468 if (!Preheader) {
12
Assuming 'Preheader' is non-null
13
Taking false branch
469 LLVM_DEBUG(dbgs() << "LoopSink: Can't find preheader\n")do { } while (false);
470 continue;
471 }
472 SmallVector<MachineInstr *, 8> Candidates;
473 FindLoopSinkCandidates(L, Preheader, Candidates);
474
475 // Walk the candidates in reverse order so that we start with the use
476 // of a def-use chain, if there is any.
477 // TODO: Sort the candidates using a cost-model.
478 unsigned i = 0;
479 for (auto It = Candidates.rbegin(); It != Candidates.rend(); ++It) {
14
Loop condition is true. Entering loop body
480 if (i++ == SinkIntoLoopLimit) {
15
Assuming the condition is false
16
Taking false branch
481 LLVM_DEBUG(dbgs() << "LoopSink: Limit reached of instructions to "do { } while (false)
482 "be analysed.")do { } while (false);
483 break;
484 }
485
486 MachineInstr *I = *It;
487 if (!SinkIntoLoop(L, *I))
17
Calling 'MachineSinking::SinkIntoLoop'
488 break;
489 EverMadeChange = true;
490 ++NumLoopSunk;
491 }
492 }
493 }
494
495 HasStoreCache.clear();
496 StoreInstrCache.clear();
497
498 // Now clear any kill flags for recorded registers.
499 for (auto I : RegsToClearKillFlags)
500 MRI->clearKillFlags(I);
501 RegsToClearKillFlags.clear();
502
503 return EverMadeChange;
504}
505
506bool MachineSinking::ProcessBlock(MachineBasicBlock &MBB) {
507 // Can't sink anything out of a block that has less than two successors.
508 if (MBB.succ_size() <= 1 || MBB.empty()) return false;
509
510 // Don't bother sinking code out of unreachable blocks. In addition to being
511 // unprofitable, it can also lead to infinite looping, because in an
512 // unreachable loop there may be nowhere to stop.
513 if (!DT->isReachableFromEntry(&MBB)) return false;
514
515 bool MadeChange = false;
516
517 // Cache all successors, sorted by frequency info and loop depth.
518 AllSuccsCache AllSuccessors;
519
520 // Walk the basic block bottom-up. Remember if we saw a store.
521 MachineBasicBlock::iterator I = MBB.end();
522 --I;
523 bool ProcessedBegin, SawStore = false;
524 do {
525 MachineInstr &MI = *I; // The instruction to sink.
526
527 // Predecrement I (if it's not begin) so that it isn't invalidated by
528 // sinking.
529 ProcessedBegin = I == MBB.begin();
530 if (!ProcessedBegin)
531 --I;
532
533 if (MI.isDebugOrPseudoInstr()) {
534 if (MI.isDebugValue())
535 ProcessDbgInst(MI);
536 continue;
537 }
538
539 bool Joined = PerformTrivialForwardCoalescing(MI, &MBB);
540 if (Joined) {
541 MadeChange = true;
542 continue;
543 }
544
545 if (SinkInstruction(MI, SawStore, AllSuccessors)) {
546 ++NumSunk;
547 MadeChange = true;
548 }
549
550 // If we just processed the first instruction in the block, we're done.
551 } while (!ProcessedBegin);
552
553 SeenDbgUsers.clear();
554 SeenDbgVars.clear();
555 // recalculate the bb register pressure after sinking one BB.
556 CachedRegisterPressure.clear();
557
558 return MadeChange;
559}
560
561void MachineSinking::ProcessDbgInst(MachineInstr &MI) {
562 // When we see DBG_VALUEs for registers, record any vreg it reads, so that
563 // we know what to sink if the vreg def sinks.
564 assert(MI.isDebugValue() && "Expected DBG_VALUE for processing")((void)0);
565
566 DebugVariable Var(MI.getDebugVariable(), MI.getDebugExpression(),
567 MI.getDebugLoc()->getInlinedAt());
568 bool SeenBefore = SeenDbgVars.contains(Var);
569
570 for (MachineOperand &MO : MI.debug_operands()) {
571 if (MO.isReg() && MO.getReg().isVirtual())
572 SeenDbgUsers[MO.getReg()].push_back(SeenDbgUser(&MI, SeenBefore));
573 }
574
575 // Record the variable for any DBG_VALUE, to avoid re-ordering any of them.
576 SeenDbgVars.insert(Var);
577}
578
579bool MachineSinking::isWorthBreakingCriticalEdge(MachineInstr &MI,
580 MachineBasicBlock *From,
581 MachineBasicBlock *To) {
582 // FIXME: Need much better heuristics.
583
584 // If the pass has already considered breaking this edge (during this pass
585 // through the function), then let's go ahead and break it. This means
586 // sinking multiple "cheap" instructions into the same block.
587 if (!CEBCandidates.insert(std::make_pair(From, To)).second)
588 return true;
589
590 if (!MI.isCopy() && !TII->isAsCheapAsAMove(MI))
591 return true;
592
593 if (From->isSuccessor(To) && MBPI->getEdgeProbability(From, To) <=
594 BranchProbability(SplitEdgeProbabilityThreshold, 100))
595 return true;
596
597 // MI is cheap, we probably don't want to break the critical edge for it.
598 // However, if this would allow some definitions of its source operands
599 // to be sunk then it's probably worth it.
600 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
601 const MachineOperand &MO = MI.getOperand(i);
602 if (!MO.isReg() || !MO.isUse())
603 continue;
604 Register Reg = MO.getReg();
605 if (Reg == 0)
606 continue;
607
608 // We don't move live definitions of physical registers,
609 // so sinking their uses won't enable any opportunities.
610 if (Register::isPhysicalRegister(Reg))
611 continue;
612
613 // If this instruction is the only user of a virtual register,
614 // check if breaking the edge will enable sinking
615 // both this instruction and the defining instruction.
616 if (MRI->hasOneNonDBGUse(Reg)) {
617 // If the definition resides in same MBB,
618 // claim it's likely we can sink these together.
619 // If definition resides elsewhere, we aren't
620 // blocking it from being sunk so don't break the edge.
621 MachineInstr *DefMI = MRI->getVRegDef(Reg);
622 if (DefMI->getParent() == MI.getParent())
623 return true;
624 }
625 }
626
627 return false;
628}
629
630bool MachineSinking::PostponeSplitCriticalEdge(MachineInstr &MI,
631 MachineBasicBlock *FromBB,
632 MachineBasicBlock *ToBB,
633 bool BreakPHIEdge) {
634 if (!isWorthBreakingCriticalEdge(MI, FromBB, ToBB))
635 return false;
636
637 // Avoid breaking back edge. From == To means backedge for single BB loop.
638 if (!SplitEdges || FromBB == ToBB)
639 return false;
640
641 // Check for backedges of more "complex" loops.
642 if (LI->getLoopFor(FromBB) == LI->getLoopFor(ToBB) &&
643 LI->isLoopHeader(ToBB))
644 return false;
645
646 // It's not always legal to break critical edges and sink the computation
647 // to the edge.
648 //
649 // %bb.1:
650 // v1024
651 // Beq %bb.3
652 // <fallthrough>
653 // %bb.2:
654 // ... no uses of v1024
655 // <fallthrough>
656 // %bb.3:
657 // ...
658 // = v1024
659 //
660 // If %bb.1 -> %bb.3 edge is broken and computation of v1024 is inserted:
661 //
662 // %bb.1:
663 // ...
664 // Bne %bb.2
665 // %bb.4:
666 // v1024 =
667 // B %bb.3
668 // %bb.2:
669 // ... no uses of v1024
670 // <fallthrough>
671 // %bb.3:
672 // ...
673 // = v1024
674 //
675 // This is incorrect since v1024 is not computed along the %bb.1->%bb.2->%bb.3
676 // flow. We need to ensure the new basic block where the computation is
677 // sunk to dominates all the uses.
678 // It's only legal to break critical edge and sink the computation to the
679 // new block if all the predecessors of "To", except for "From", are
680 // not dominated by "From". Given SSA property, this means these
681 // predecessors are dominated by "To".
682 //
683 // There is no need to do this check if all the uses are PHI nodes. PHI
684 // sources are only defined on the specific predecessor edges.
685 if (!BreakPHIEdge) {
686 for (MachineBasicBlock::pred_iterator PI = ToBB->pred_begin(),
687 E = ToBB->pred_end(); PI != E; ++PI) {
688 if (*PI == FromBB)
689 continue;
690 if (!DT->dominates(ToBB, *PI))
691 return false;
692 }
693 }
694
695 ToSplit.insert(std::make_pair(FromBB, ToBB));
696
697 return true;
698}
699
700std::vector<unsigned> &
701MachineSinking::getBBRegisterPressure(MachineBasicBlock &MBB) {
702 // Currently to save compiling time, MBB's register pressure will not change
703 // in one ProcessBlock iteration because of CachedRegisterPressure. but MBB's
704 // register pressure is changed after sinking any instructions into it.
705 // FIXME: need a accurate and cheap register pressure estiminate model here.
706 auto RP = CachedRegisterPressure.find(&MBB);
707 if (RP != CachedRegisterPressure.end())
708 return RP->second;
709
710 RegionPressure Pressure;
711 RegPressureTracker RPTracker(Pressure);
712
713 // Initialize the register pressure tracker.
714 RPTracker.init(MBB.getParent(), &RegClassInfo, nullptr, &MBB, MBB.end(),
715 /*TrackLaneMasks*/ false, /*TrackUntiedDefs=*/true);
716
717 for (MachineBasicBlock::iterator MII = MBB.instr_end(),
718 MIE = MBB.instr_begin();
719 MII != MIE; --MII) {
720 MachineInstr &MI = *std::prev(MII);
721 if (MI.isDebugInstr() || MI.isPseudoProbe())
722 continue;
723 RegisterOperands RegOpers;
724 RegOpers.collect(MI, *TRI, *MRI, false, false);
725 RPTracker.recedeSkipDebugValues();
726 assert(&*RPTracker.getPos() == &MI && "RPTracker sync error!")((void)0);
727 RPTracker.recede(RegOpers);
728 }
729
730 RPTracker.closeRegion();
731 auto It = CachedRegisterPressure.insert(
732 std::make_pair(&MBB, RPTracker.getPressure().MaxSetPressure));
733 return It.first->second;
734}
735
736/// isProfitableToSinkTo - Return true if it is profitable to sink MI.
737bool MachineSinking::isProfitableToSinkTo(Register Reg, MachineInstr &MI,
738 MachineBasicBlock *MBB,
739 MachineBasicBlock *SuccToSinkTo,
740 AllSuccsCache &AllSuccessors) {
741 assert (SuccToSinkTo && "Invalid SinkTo Candidate BB")((void)0);
742
743 if (MBB == SuccToSinkTo)
744 return false;
745
746 // It is profitable if SuccToSinkTo does not post dominate current block.
747 if (!PDT->dominates(SuccToSinkTo, MBB))
748 return true;
749
750 // It is profitable to sink an instruction from a deeper loop to a shallower
751 // loop, even if the latter post-dominates the former (PR21115).
752 if (LI->getLoopDepth(MBB) > LI->getLoopDepth(SuccToSinkTo))
753 return true;
754
755 // Check if only use in post dominated block is PHI instruction.
756 bool NonPHIUse = false;
757 for (MachineInstr &UseInst : MRI->use_nodbg_instructions(Reg)) {
758 MachineBasicBlock *UseBlock = UseInst.getParent();
759 if (UseBlock == SuccToSinkTo && !UseInst.isPHI())
760 NonPHIUse = true;
761 }
762 if (!NonPHIUse)
763 return true;
764
765 // If SuccToSinkTo post dominates then also it may be profitable if MI
766 // can further profitably sinked into another block in next round.
767 bool BreakPHIEdge = false;
768 // FIXME - If finding successor is compile time expensive then cache results.
769 if (MachineBasicBlock *MBB2 =
770 FindSuccToSinkTo(MI, SuccToSinkTo, BreakPHIEdge, AllSuccessors))
771 return isProfitableToSinkTo(Reg, MI, SuccToSinkTo, MBB2, AllSuccessors);
772
773 MachineLoop *ML = LI->getLoopFor(MBB);
774
775 // If the instruction is not inside a loop, it is not profitable to sink MI to
776 // a post dominate block SuccToSinkTo.
777 if (!ML)
778 return false;
779
780 auto isRegisterPressureSetExceedLimit = [&](const TargetRegisterClass *RC) {
781 unsigned Weight = TRI->getRegClassWeight(RC).RegWeight;
782 const int *PS = TRI->getRegClassPressureSets(RC);
783 // Get register pressure for block SuccToSinkTo.
784 std::vector<unsigned> BBRegisterPressure =
785 getBBRegisterPressure(*SuccToSinkTo);
786 for (; *PS != -1; PS++)
787 // check if any register pressure set exceeds limit in block SuccToSinkTo
788 // after sinking.
789 if (Weight + BBRegisterPressure[*PS] >=
790 TRI->getRegPressureSetLimit(*MBB->getParent(), *PS))
791 return true;
792 return false;
793 };
794
795 // If this instruction is inside a loop and sinking this instruction can make
796 // more registers live range shorten, it is still prifitable.
797 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
798 const MachineOperand &MO = MI.getOperand(i);
799 // Ignore non-register operands.
800 if (!MO.isReg())
801 continue;
802 Register Reg = MO.getReg();
803 if (Reg == 0)
804 continue;
805
806 // Don't handle physical register.
807 if (Register::isPhysicalRegister(Reg))
808 return false;
809
810 // Users for the defs are all dominated by SuccToSinkTo.
811 if (MO.isDef()) {
812 // This def register's live range is shortened after sinking.
813 bool LocalUse = false;
814 if (!AllUsesDominatedByBlock(Reg, SuccToSinkTo, MBB, BreakPHIEdge,
815 LocalUse))
816 return false;
817 } else {
818 MachineInstr *DefMI = MRI->getVRegDef(Reg);
819 // DefMI is defined outside of loop. There should be no live range
820 // impact for this operand. Defination outside of loop means:
821 // 1: defination is outside of loop.
822 // 2: defination is in this loop, but it is a PHI in the loop header.
823 if (LI->getLoopFor(DefMI->getParent()) != ML ||
824 (DefMI->isPHI() && LI->isLoopHeader(DefMI->getParent())))
825 continue;
826 // The DefMI is defined inside the loop.
827 // If sinking this operand makes some register pressure set exceed limit,
828 // it is not profitable.
829 if (isRegisterPressureSetExceedLimit(MRI->getRegClass(Reg))) {
830 LLVM_DEBUG(dbgs() << "register pressure exceed limit, not profitable.")do { } while (false);
831 return false;
832 }
833 }
834 }
835
836 // If MI is in loop and all its operands are alive across the whole loop or if
837 // no operand sinking make register pressure set exceed limit, it is
838 // profitable to sink MI.
839 return true;
840}
841
842/// Get the sorted sequence of successors for this MachineBasicBlock, possibly
843/// computing it if it was not already cached.
844SmallVector<MachineBasicBlock *, 4> &
845MachineSinking::GetAllSortedSuccessors(MachineInstr &MI, MachineBasicBlock *MBB,
846 AllSuccsCache &AllSuccessors) const {
847 // Do we have the sorted successors in cache ?
848 auto Succs = AllSuccessors.find(MBB);
849 if (Succs != AllSuccessors.end())
850 return Succs->second;
851
852 SmallVector<MachineBasicBlock *, 4> AllSuccs(MBB->successors());
853
854 // Handle cases where sinking can happen but where the sink point isn't a
855 // successor. For example:
856 //
857 // x = computation
858 // if () {} else {}
859 // use x
860 //
861 for (MachineDomTreeNode *DTChild : DT->getNode(MBB)->children()) {
862 // DomTree children of MBB that have MBB as immediate dominator are added.
863 if (DTChild->getIDom()->getBlock() == MI.getParent() &&
864 // Skip MBBs already added to the AllSuccs vector above.
865 !MBB->isSuccessor(DTChild->getBlock()))
866 AllSuccs.push_back(DTChild->getBlock());
867 }
868
869 // Sort Successors according to their loop depth or block frequency info.
870 llvm::stable_sort(
871 AllSuccs, [this](const MachineBasicBlock *L, const MachineBasicBlock *R) {
872 uint64_t LHSFreq = MBFI ? MBFI->getBlockFreq(L).getFrequency() : 0;
873 uint64_t RHSFreq = MBFI ? MBFI->getBlockFreq(R).getFrequency() : 0;
874 bool HasBlockFreq = LHSFreq != 0 && RHSFreq != 0;
875 return HasBlockFreq ? LHSFreq < RHSFreq
876 : LI->getLoopDepth(L) < LI->getLoopDepth(R);
877 });
878
879 auto it = AllSuccessors.insert(std::make_pair(MBB, AllSuccs));
880
881 return it.first->second;
882}
883
884/// FindSuccToSinkTo - Find a successor to sink this instruction to.
885MachineBasicBlock *
886MachineSinking::FindSuccToSinkTo(MachineInstr &MI, MachineBasicBlock *MBB,
887 bool &BreakPHIEdge,
888 AllSuccsCache &AllSuccessors) {
889 assert (MBB && "Invalid MachineBasicBlock!")((void)0);
890
891 // Loop over all the operands of the specified instruction. If there is
892 // anything we can't handle, bail out.
893
894 // SuccToSinkTo - This is the successor to sink this instruction to, once we
895 // decide.
896 MachineBasicBlock *SuccToSinkTo = nullptr;
897 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
898 const MachineOperand &MO = MI.getOperand(i);
899 if (!MO.isReg()) continue; // Ignore non-register operands.
900
901 Register Reg = MO.getReg();
902 if (Reg == 0) continue;
903
904 if (Register::isPhysicalRegister(Reg)) {
905 if (MO.isUse()) {
906 // If the physreg has no defs anywhere, it's just an ambient register
907 // and we can freely move its uses. Alternatively, if it's allocatable,
908 // it could get allocated to something with a def during allocation.
909 if (!MRI->isConstantPhysReg(Reg))
910 return nullptr;
911 } else if (!MO.isDead()) {
912 // A def that isn't dead. We can't move it.
913 return nullptr;
914 }
915 } else {
916 // Virtual register uses are always safe to sink.
917 if (MO.isUse()) continue;
918
919 // If it's not safe to move defs of the register class, then abort.
920 if (!TII->isSafeToMoveRegClassDefs(MRI->getRegClass(Reg)))
921 return nullptr;
922
923 // Virtual register defs can only be sunk if all their uses are in blocks
924 // dominated by one of the successors.
925 if (SuccToSinkTo) {
926 // If a previous operand picked a block to sink to, then this operand
927 // must be sinkable to the same block.
928 bool LocalUse = false;
929 if (!AllUsesDominatedByBlock(Reg, SuccToSinkTo, MBB,
930 BreakPHIEdge, LocalUse))
931 return nullptr;
932
933 continue;
934 }
935
936 // Otherwise, we should look at all the successors and decide which one
937 // we should sink to. If we have reliable block frequency information
938 // (frequency != 0) available, give successors with smaller frequencies
939 // higher priority, otherwise prioritize smaller loop depths.
940 for (MachineBasicBlock *SuccBlock :
941 GetAllSortedSuccessors(MI, MBB, AllSuccessors)) {
942 bool LocalUse = false;
943 if (AllUsesDominatedByBlock(Reg, SuccBlock, MBB,
944 BreakPHIEdge, LocalUse)) {
945 SuccToSinkTo = SuccBlock;
946 break;
947 }
948 if (LocalUse)
949 // Def is used locally, it's never safe to move this def.
950 return nullptr;
951 }
952
953 // If we couldn't find a block to sink to, ignore this instruction.
954 if (!SuccToSinkTo)
955 return nullptr;
956 if (!isProfitableToSinkTo(Reg, MI, MBB, SuccToSinkTo, AllSuccessors))
957 return nullptr;
958 }
959 }
960
961 // It is not possible to sink an instruction into its own block. This can
962 // happen with loops.
963 if (MBB == SuccToSinkTo)
964 return nullptr;
965
966 // It's not safe to sink instructions to EH landing pad. Control flow into
967 // landing pad is implicitly defined.
968 if (SuccToSinkTo && SuccToSinkTo->isEHPad())
969 return nullptr;
970
971 // It ought to be okay to sink instructions into an INLINEASM_BR target, but
972 // only if we make sure that MI occurs _before_ an INLINEASM_BR instruction in
973 // the source block (which this code does not yet do). So for now, forbid
974 // doing so.
975 if (SuccToSinkTo && SuccToSinkTo->isInlineAsmBrIndirectTarget())
976 return nullptr;
977
978 return SuccToSinkTo;
979}
980
981/// Return true if MI is likely to be usable as a memory operation by the
982/// implicit null check optimization.
983///
984/// This is a "best effort" heuristic, and should not be relied upon for
985/// correctness. This returning true does not guarantee that the implicit null
986/// check optimization is legal over MI, and this returning false does not
987/// guarantee MI cannot possibly be used to do a null check.
988static bool SinkingPreventsImplicitNullCheck(MachineInstr &MI,
989 const TargetInstrInfo *TII,
990 const TargetRegisterInfo *TRI) {
991 using MachineBranchPredicate = TargetInstrInfo::MachineBranchPredicate;
992
993 auto *MBB = MI.getParent();
994 if (MBB->pred_size() != 1)
995 return false;
996
997 auto *PredMBB = *MBB->pred_begin();
998 auto *PredBB = PredMBB->getBasicBlock();
999
1000 // Frontends that don't use implicit null checks have no reason to emit
1001 // branches with make.implicit metadata, and this function should always
1002 // return false for them.
1003 if (!PredBB ||
1004 !PredBB->getTerminator()->getMetadata(LLVMContext::MD_make_implicit))
1005 return false;
1006
1007 const MachineOperand *BaseOp;
1008 int64_t Offset;
1009 bool OffsetIsScalable;
1010 if (!TII->getMemOperandWithOffset(MI, BaseOp, Offset, OffsetIsScalable, TRI))
1011 return false;
1012
1013 if (!BaseOp->isReg())
1014 return false;
1015
1016 if (!(MI.mayLoad() && !MI.isPredicable()))
1017 return false;
1018
1019 MachineBranchPredicate MBP;
1020 if (TII->analyzeBranchPredicate(*PredMBB, MBP, false))
1021 return false;
1022
1023 return MBP.LHS.isReg() && MBP.RHS.isImm() && MBP.RHS.getImm() == 0 &&
1024 (MBP.Predicate == MachineBranchPredicate::PRED_NE ||
1025 MBP.Predicate == MachineBranchPredicate::PRED_EQ) &&
1026 MBP.LHS.getReg() == BaseOp->getReg();
1027}
1028
1029/// If the sunk instruction is a copy, try to forward the copy instead of
1030/// leaving an 'undef' DBG_VALUE in the original location. Don't do this if
1031/// there's any subregister weirdness involved. Returns true if copy
1032/// propagation occurred.
1033static bool attemptDebugCopyProp(MachineInstr &SinkInst, MachineInstr &DbgMI,
1034 Register Reg) {
1035 const MachineRegisterInfo &MRI = SinkInst.getMF()->getRegInfo();
1036 const TargetInstrInfo &TII = *SinkInst.getMF()->getSubtarget().getInstrInfo();
1037
1038 // Copy DBG_VALUE operand and set the original to undef. We then check to
1039 // see whether this is something that can be copy-forwarded. If it isn't,
1040 // continue around the loop.
1041
1042 const MachineOperand *SrcMO = nullptr, *DstMO = nullptr;
1043 auto CopyOperands = TII.isCopyInstr(SinkInst);
1044 if (!CopyOperands)
1045 return false;
1046 SrcMO = CopyOperands->Source;
1047 DstMO = CopyOperands->Destination;
1048
1049 // Check validity of forwarding this copy.
1050 bool PostRA = MRI.getNumVirtRegs() == 0;
1051
1052 // Trying to forward between physical and virtual registers is too hard.
1053 if (Reg.isVirtual() != SrcMO->getReg().isVirtual())
1054 return false;
1055
1056 // Only try virtual register copy-forwarding before regalloc, and physical
1057 // register copy-forwarding after regalloc.
1058 bool arePhysRegs = !Reg.isVirtual();
1059 if (arePhysRegs != PostRA)
1060 return false;
1061
1062 // Pre-regalloc, only forward if all subregisters agree (or there are no
1063 // subregs at all). More analysis might recover some forwardable copies.
1064 if (!PostRA)
1065 for (auto &DbgMO : DbgMI.getDebugOperandsForReg(Reg))
1066 if (DbgMO.getSubReg() != SrcMO->getSubReg() ||
1067 DbgMO.getSubReg() != DstMO->getSubReg())
1068 return false;
1069
1070 // Post-regalloc, we may be sinking a DBG_VALUE of a sub or super-register
1071 // of this copy. Only forward the copy if the DBG_VALUE operand exactly
1072 // matches the copy destination.
1073 if (PostRA && Reg != DstMO->getReg())
1074 return false;
1075
1076 for (auto &DbgMO : DbgMI.getDebugOperandsForReg(Reg)) {
1077 DbgMO.setReg(SrcMO->getReg());
1078 DbgMO.setSubReg(SrcMO->getSubReg());
1079 }
1080 return true;
1081}
1082
1083using MIRegs = std::pair<MachineInstr *, SmallVector<unsigned, 2>>;
1084/// Sink an instruction and its associated debug instructions.
1085static void performSink(MachineInstr &MI, MachineBasicBlock &SuccToSinkTo,
1086 MachineBasicBlock::iterator InsertPos,
1087 SmallVectorImpl<MIRegs> &DbgValuesToSink) {
1088
1089 // If we cannot find a location to use (merge with), then we erase the debug
1090 // location to prevent debug-info driven tools from potentially reporting
1091 // wrong location information.
1092 if (!SuccToSinkTo.empty() && InsertPos != SuccToSinkTo.end())
1093 MI.setDebugLoc(DILocation::getMergedLocation(MI.getDebugLoc(),
1094 InsertPos->getDebugLoc()));
1095 else
1096 MI.setDebugLoc(DebugLoc());
1097
1098 // Move the instruction.
1099 MachineBasicBlock *ParentBlock = MI.getParent();
1100 SuccToSinkTo.splice(InsertPos, ParentBlock, MI,
1101 ++MachineBasicBlock::iterator(MI));
1102
1103 // Sink a copy of debug users to the insert position. Mark the original
1104 // DBG_VALUE location as 'undef', indicating that any earlier variable
1105 // location should be terminated as we've optimised away the value at this
1106 // point.
1107 for (auto DbgValueToSink : DbgValuesToSink) {
1108 MachineInstr *DbgMI = DbgValueToSink.first;
1109 MachineInstr *NewDbgMI = DbgMI->getMF()->CloneMachineInstr(DbgMI);
1110 SuccToSinkTo.insert(InsertPos, NewDbgMI);
1111
1112 bool PropagatedAllSunkOps = true;
1113 for (unsigned Reg : DbgValueToSink.second) {
1114 if (DbgMI->hasDebugOperandForReg(Reg)) {
1115 if (!attemptDebugCopyProp(MI, *DbgMI, Reg)) {
1116 PropagatedAllSunkOps = false;
1117 break;
1118 }
1119 }
1120 }
1121 if (!PropagatedAllSunkOps)
1122 DbgMI->setDebugValueUndef();
1123 }
1124}
1125
1126/// hasStoreBetween - check if there is store betweeen straight line blocks From
1127/// and To.
1128bool MachineSinking::hasStoreBetween(MachineBasicBlock *From,
1129 MachineBasicBlock *To, MachineInstr &MI) {
1130 // Make sure From and To are in straight line which means From dominates To
1131 // and To post dominates From.
1132 if (!DT->dominates(From, To) || !PDT->dominates(To, From))
1133 return true;
1134
1135 auto BlockPair = std::make_pair(From, To);
1136
1137 // Does these two blocks pair be queried before and have a definite cached
1138 // result?
1139 if (HasStoreCache.find(BlockPair) != HasStoreCache.end())
1140 return HasStoreCache[BlockPair];
1141
1142 if (StoreInstrCache.find(BlockPair) != StoreInstrCache.end())
1143 return llvm::any_of(StoreInstrCache[BlockPair], [&](MachineInstr *I) {
1144 return I->mayAlias(AA, MI, false);
1145 });
1146
1147 bool SawStore = false;
1148 bool HasAliasedStore = false;
1149 DenseSet<MachineBasicBlock *> HandledBlocks;
1150 DenseSet<MachineBasicBlock *> HandledDomBlocks;
1151 // Go through all reachable blocks from From.
1152 for (MachineBasicBlock *BB : depth_first(From)) {
1153 // We insert the instruction at the start of block To, so no need to worry
1154 // about stores inside To.
1155 // Store in block From should be already considered when just enter function
1156 // SinkInstruction.
1157 if (BB == To || BB == From)
1158 continue;
1159
1160 // We already handle this BB in previous iteration.
1161 if (HandledBlocks.count(BB))
1162 continue;
1163
1164 HandledBlocks.insert(BB);
1165 // To post dominates BB, it must be a path from block From.
1166 if (PDT->dominates(To, BB)) {
1167 if (!HandledDomBlocks.count(BB))
1168 HandledDomBlocks.insert(BB);
1169
1170 // If this BB is too big or the block number in straight line between From
1171 // and To is too big, stop searching to save compiling time.
1172 if (BB->size() > SinkLoadInstsPerBlockThreshold ||
1173 HandledDomBlocks.size() > SinkLoadBlocksThreshold) {
1174 for (auto *DomBB : HandledDomBlocks) {
1175 if (DomBB != BB && DT->dominates(DomBB, BB))
1176 HasStoreCache[std::make_pair(DomBB, To)] = true;
1177 else if(DomBB != BB && DT->dominates(BB, DomBB))
1178 HasStoreCache[std::make_pair(From, DomBB)] = true;
1179 }
1180 HasStoreCache[BlockPair] = true;
1181 return true;
1182 }
1183
1184 for (MachineInstr &I : *BB) {
1185 // Treat as alias conservatively for a call or an ordered memory
1186 // operation.
1187 if (I.isCall() || I.hasOrderedMemoryRef()) {
1188 for (auto *DomBB : HandledDomBlocks) {
1189 if (DomBB != BB && DT->dominates(DomBB, BB))
1190 HasStoreCache[std::make_pair(DomBB, To)] = true;
1191 else if(DomBB != BB && DT->dominates(BB, DomBB))
1192 HasStoreCache[std::make_pair(From, DomBB)] = true;
1193 }
1194 HasStoreCache[BlockPair] = true;
1195 return true;
1196 }
1197
1198 if (I.mayStore()) {
1199 SawStore = true;
1200 // We still have chance to sink MI if all stores between are not
1201 // aliased to MI.
1202 // Cache all store instructions, so that we don't need to go through
1203 // all From reachable blocks for next load instruction.
1204 if (I.mayAlias(AA, MI, false))
1205 HasAliasedStore = true;
1206 StoreInstrCache[BlockPair].push_back(&I);
1207 }
1208 }
1209 }
1210 }
1211 // If there is no store at all, cache the result.
1212 if (!SawStore)
1213 HasStoreCache[BlockPair] = false;
1214 return HasAliasedStore;
1215}
1216
1217/// Sink instructions into loops if profitable. This especially tries to prevent
1218/// register spills caused by register pressure if there is little to no
1219/// overhead moving instructions into loops.
1220bool MachineSinking::SinkIntoLoop(MachineLoop *L, MachineInstr &I) {
1221 LLVM_DEBUG(dbgs() << "LoopSink: Finding sink block for: " << I)do { } while (false);
18
Loop condition is false. Exiting loop
1222 MachineBasicBlock *Preheader = L->getLoopPreheader();
1223 assert(Preheader && "Loop sink needs a preheader block")((void)0);
1224 MachineBasicBlock *SinkBlock = nullptr;
1225 bool CanSink = true;
1226 const MachineOperand &MO = I.getOperand(0);
1227
1228 for (MachineInstr &MI : MRI->use_instructions(MO.getReg())) {
1229 LLVM_DEBUG(dbgs() << "LoopSink: Analysing use: " << MI)do { } while (false);
19
Loop condition is false. Exiting loop
26
Loop condition is false. Exiting loop
1230 if (!L->contains(&MI)) {
20
Assuming the condition is false
21
Taking false branch
27
Assuming the condition is false
28
Taking false branch
1231 LLVM_DEBUG(dbgs() << "LoopSink: Use not in loop, can't sink.\n")do { } while (false);
1232 CanSink = false;
1233 break;
1234 }
1235
1236 // FIXME: Come up with a proper cost model that estimates whether sinking
1237 // the instruction (and thus possibly executing it on every loop
1238 // iteration) is more expensive than a register.
1239 // For now assumes that copies are cheap and thus almost always worth it.
1240 if (!MI.isCopy()) {
22
Taking false branch
29
Taking false branch
1241 LLVM_DEBUG(dbgs() << "LoopSink: Use is not a copy\n")do { } while (false);
1242 CanSink = false;
1243 break;
1244 }
1245 if (!SinkBlock
22.1
'SinkBlock' is null
22.1
'SinkBlock' is null
22.1
'SinkBlock' is null
22.1
'SinkBlock' is null
) {
23
Taking true branch
30
Assuming 'SinkBlock' is non-null
31
Taking false branch
1246 SinkBlock = MI.getParent();
1247 LLVM_DEBUG(dbgs() << "LoopSink: Setting sink block to: "do { } while (false)
24
Loop condition is false. Exiting loop
1248 << printMBBReference(*SinkBlock) << "\n")do { } while (false);
1249 continue;
25
Execution continues on line 1228
1250 }
1251 SinkBlock = DT->findNearestCommonDominator(SinkBlock, MI.getParent());
32
Calling 'MachineDominatorTree::findNearestCommonDominator'
1252 if (!SinkBlock) {
1253 LLVM_DEBUG(dbgs() << "LoopSink: Can't find nearest dominator\n")do { } while (false);
1254 CanSink = false;
1255 break;
1256 }
1257 LLVM_DEBUG(dbgs() << "LoopSink: Setting nearest common dom block: " <<do { } while (false)
1258 printMBBReference(*SinkBlock) << "\n")do { } while (false);
1259 }
1260
1261 if (!CanSink) {
1262 LLVM_DEBUG(dbgs() << "LoopSink: Can't sink instruction.\n")do { } while (false);
1263 return false;
1264 }
1265 if (!SinkBlock) {
1266 LLVM_DEBUG(dbgs() << "LoopSink: Not sinking, can't find sink block.\n")do { } while (false);
1267 return false;
1268 }
1269 if (SinkBlock == Preheader) {
1270 LLVM_DEBUG(dbgs() << "LoopSink: Not sinking, sink block is the preheader\n")do { } while (false);
1271 return false;
1272 }
1273 if (SinkBlock->size() > SinkLoadInstsPerBlockThreshold) {
1274 LLVM_DEBUG(dbgs() << "LoopSink: Not Sinking, block too large to analyse.\n")do { } while (false);
1275 return false;
1276 }
1277
1278 LLVM_DEBUG(dbgs() << "LoopSink: Sinking instruction!\n")do { } while (false);
1279 SinkBlock->splice(SinkBlock->getFirstNonPHI(), Preheader, I);
1280
1281 // The instruction is moved from its basic block, so do not retain the
1282 // debug information.
1283 assert(!I.isDebugInstr() && "Should not sink debug inst")((void)0);
1284 I.setDebugLoc(DebugLoc());
1285 return true;
1286}
1287
1288/// SinkInstruction - Determine whether it is safe to sink the specified machine
1289/// instruction out of its current block into a successor.
1290bool MachineSinking::SinkInstruction(MachineInstr &MI, bool &SawStore,
1291 AllSuccsCache &AllSuccessors) {
1292 // Don't sink instructions that the target prefers not to sink.
1293 if (!TII->shouldSink(MI))
1294 return false;
1295
1296 // Check if it's safe to move the instruction.
1297 if (!MI.isSafeToMove(AA, SawStore))
1298 return false;
1299
1300 // Convergent operations may not be made control-dependent on additional
1301 // values.
1302 if (MI.isConvergent())
1303 return false;
1304
1305 // Don't break implicit null checks. This is a performance heuristic, and not
1306 // required for correctness.
1307 if (SinkingPreventsImplicitNullCheck(MI, TII, TRI))
1308 return false;
1309
1310 // FIXME: This should include support for sinking instructions within the
1311 // block they are currently in to shorten the live ranges. We often get
1312 // instructions sunk into the top of a large block, but it would be better to
1313 // also sink them down before their first use in the block. This xform has to
1314 // be careful not to *increase* register pressure though, e.g. sinking
1315 // "x = y + z" down if it kills y and z would increase the live ranges of y
1316 // and z and only shrink the live range of x.
1317
1318 bool BreakPHIEdge = false;
1319 MachineBasicBlock *ParentBlock = MI.getParent();
1320 MachineBasicBlock *SuccToSinkTo =
1321 FindSuccToSinkTo(MI, ParentBlock, BreakPHIEdge, AllSuccessors);
1322
1323 // If there are no outputs, it must have side-effects.
1324 if (!SuccToSinkTo)
1325 return false;
1326
1327 // If the instruction to move defines a dead physical register which is live
1328 // when leaving the basic block, don't move it because it could turn into a
1329 // "zombie" define of that preg. E.g., EFLAGS. (<rdar://problem/8030636>)
1330 for (unsigned I = 0, E = MI.getNumOperands(); I != E; ++I) {
1331 const MachineOperand &MO = MI.getOperand(I);
1332 if (!MO.isReg()) continue;
1333 Register Reg = MO.getReg();
1334 if (Reg == 0 || !Register::isPhysicalRegister(Reg))
1335 continue;
1336 if (SuccToSinkTo->isLiveIn(Reg))
1337 return false;
1338 }
1339
1340 LLVM_DEBUG(dbgs() << "Sink instr " << MI << "\tinto block " << *SuccToSinkTo)do { } while (false);
1341
1342 // If the block has multiple predecessors, this is a critical edge.
1343 // Decide if we can sink along it or need to break the edge.
1344 if (SuccToSinkTo->pred_size() > 1) {
1345 // We cannot sink a load across a critical edge - there may be stores in
1346 // other code paths.
1347 bool TryBreak = false;
1348 bool Store =
1349 MI.mayLoad() ? hasStoreBetween(ParentBlock, SuccToSinkTo, MI) : true;
1350 if (!MI.isSafeToMove(AA, Store)) {
1351 LLVM_DEBUG(dbgs() << " *** NOTE: Won't sink load along critical edge.\n")do { } while (false);
1352 TryBreak = true;
1353 }
1354
1355 // We don't want to sink across a critical edge if we don't dominate the
1356 // successor. We could be introducing calculations to new code paths.
1357 if (!TryBreak && !DT->dominates(ParentBlock, SuccToSinkTo)) {
1358 LLVM_DEBUG(dbgs() << " *** NOTE: Critical edge found\n")do { } while (false);
1359 TryBreak = true;
1360 }
1361
1362 // Don't sink instructions into a loop.
1363 if (!TryBreak && LI->isLoopHeader(SuccToSinkTo)) {
1364 LLVM_DEBUG(dbgs() << " *** NOTE: Loop header found\n")do { } while (false);
1365 TryBreak = true;
1366 }
1367
1368 // Otherwise we are OK with sinking along a critical edge.
1369 if (!TryBreak)
1370 LLVM_DEBUG(dbgs() << "Sinking along critical edge.\n")do { } while (false);
1371 else {
1372 // Mark this edge as to be split.
1373 // If the edge can actually be split, the next iteration of the main loop
1374 // will sink MI in the newly created block.
1375 bool Status =
1376 PostponeSplitCriticalEdge(MI, ParentBlock, SuccToSinkTo, BreakPHIEdge);
1377 if (!Status)
1378 LLVM_DEBUG(dbgs() << " *** PUNTING: Not legal or profitable to "do { } while (false)
1379 "break critical edge\n")do { } while (false);
1380 // The instruction will not be sunk this time.
1381 return false;
1382 }
1383 }
1384
1385 if (BreakPHIEdge) {
1386 // BreakPHIEdge is true if all the uses are in the successor MBB being
1387 // sunken into and they are all PHI nodes. In this case, machine-sink must
1388 // break the critical edge first.
1389 bool Status = PostponeSplitCriticalEdge(MI, ParentBlock,
1390 SuccToSinkTo, BreakPHIEdge);
1391 if (!Status)
1392 LLVM_DEBUG(dbgs() << " *** PUNTING: Not legal or profitable to "do { } while (false)
1393 "break critical edge\n")do { } while (false);
1394 // The instruction will not be sunk this time.
1395 return false;
1396 }
1397
1398 // Determine where to insert into. Skip phi nodes.
1399 MachineBasicBlock::iterator InsertPos = SuccToSinkTo->begin();
1400 while (InsertPos != SuccToSinkTo->end() && InsertPos->isPHI())
1401 ++InsertPos;
1402
1403 // Collect debug users of any vreg that this inst defines.
1404 SmallVector<MIRegs, 4> DbgUsersToSink;
1405 for (auto &MO : MI.operands()) {
1406 if (!MO.isReg() || !MO.isDef() || !MO.getReg().isVirtual())
1407 continue;
1408 if (!SeenDbgUsers.count(MO.getReg()))
1409 continue;
1410
1411 // Sink any users that don't pass any other DBG_VALUEs for this variable.
1412 auto &Users = SeenDbgUsers[MO.getReg()];
1413 for (auto &User : Users) {
1414 MachineInstr *DbgMI = User.getPointer();
1415 if (User.getInt()) {
1416 // This DBG_VALUE would re-order assignments. If we can't copy-propagate
1417 // it, it can't be recovered. Set it undef.
1418 if (!attemptDebugCopyProp(MI, *DbgMI, MO.getReg()))
1419 DbgMI->setDebugValueUndef();
1420 } else {
1421 DbgUsersToSink.push_back(
1422 {DbgMI, SmallVector<unsigned, 2>(1, MO.getReg())});
1423 }
1424 }
1425 }
1426
1427 // After sinking, some debug users may not be dominated any more. If possible,
1428 // copy-propagate their operands. As it's expensive, don't do this if there's
1429 // no debuginfo in the program.
1430 if (MI.getMF()->getFunction().getSubprogram() && MI.isCopy())
1431 SalvageUnsunkDebugUsersOfCopy(MI, SuccToSinkTo);
1432
1433 performSink(MI, *SuccToSinkTo, InsertPos, DbgUsersToSink);
1434
1435 // Conservatively, clear any kill flags, since it's possible that they are no
1436 // longer correct.
1437 // Note that we have to clear the kill flags for any register this instruction
1438 // uses as we may sink over another instruction which currently kills the
1439 // used registers.
1440 for (MachineOperand &MO : MI.operands()) {
1441 if (MO.isReg() && MO.isUse())
1442 RegsToClearKillFlags.set(MO.getReg()); // Remember to clear kill flags.
1443 }
1444
1445 return true;
1446}
1447
1448void MachineSinking::SalvageUnsunkDebugUsersOfCopy(
1449 MachineInstr &MI, MachineBasicBlock *TargetBlock) {
1450 assert(MI.isCopy())((void)0);
1451 assert(MI.getOperand(1).isReg())((void)0);
1452
1453 // Enumerate all users of vreg operands that are def'd. Skip those that will
1454 // be sunk. For the rest, if they are not dominated by the block we will sink
1455 // MI into, propagate the copy source to them.
1456 SmallVector<MachineInstr *, 4> DbgDefUsers;
1457 SmallVector<Register, 4> DbgUseRegs;
1458 const MachineRegisterInfo &MRI = MI.getMF()->getRegInfo();
1459 for (auto &MO : MI.operands()) {
1460 if (!MO.isReg() || !MO.isDef() || !MO.getReg().isVirtual())
1461 continue;
1462 DbgUseRegs.push_back(MO.getReg());
1463 for (auto &User : MRI.use_instructions(MO.getReg())) {
1464 if (!User.isDebugValue() || DT->dominates(TargetBlock, User.getParent()))
1465 continue;
1466
1467 // If is in same block, will either sink or be use-before-def.
1468 if (User.getParent() == MI.getParent())
1469 continue;
1470
1471 assert(User.hasDebugOperandForReg(MO.getReg()) &&((void)0)
1472 "DBG_VALUE user of vreg, but has no operand for it?")((void)0);
1473 DbgDefUsers.push_back(&User);
1474 }
1475 }
1476
1477 // Point the users of this copy that are no longer dominated, at the source
1478 // of the copy.
1479 for (auto *User : DbgDefUsers) {
1480 for (auto &Reg : DbgUseRegs) {
1481 for (auto &DbgOp : User->getDebugOperandsForReg(Reg)) {
1482 DbgOp.setReg(MI.getOperand(1).getReg());
1483 DbgOp.setSubReg(MI.getOperand(1).getSubReg());
1484 }
1485 }
1486 }
1487}
1488
1489//===----------------------------------------------------------------------===//
1490// This pass is not intended to be a replacement or a complete alternative
1491// for the pre-ra machine sink pass. It is only designed to sink COPY
1492// instructions which should be handled after RA.
1493//
1494// This pass sinks COPY instructions into a successor block, if the COPY is not
1495// used in the current block and the COPY is live-in to a single successor
1496// (i.e., doesn't require the COPY to be duplicated). This avoids executing the
1497// copy on paths where their results aren't needed. This also exposes
1498// additional opportunites for dead copy elimination and shrink wrapping.
1499//
1500// These copies were either not handled by or are inserted after the MachineSink
1501// pass. As an example of the former case, the MachineSink pass cannot sink
1502// COPY instructions with allocatable source registers; for AArch64 these type
1503// of copy instructions are frequently used to move function parameters (PhyReg)
1504// into virtual registers in the entry block.
1505//
1506// For the machine IR below, this pass will sink %w19 in the entry into its
1507// successor (%bb.1) because %w19 is only live-in in %bb.1.
1508// %bb.0:
1509// %wzr = SUBSWri %w1, 1
1510// %w19 = COPY %w0
1511// Bcc 11, %bb.2
1512// %bb.1:
1513// Live Ins: %w19
1514// BL @fun
1515// %w0 = ADDWrr %w0, %w19
1516// RET %w0
1517// %bb.2:
1518// %w0 = COPY %wzr
1519// RET %w0
1520// As we sink %w19 (CSR in AArch64) into %bb.1, the shrink-wrapping pass will be
1521// able to see %bb.0 as a candidate.
1522//===----------------------------------------------------------------------===//
1523namespace {
1524
1525class PostRAMachineSinking : public MachineFunctionPass {
1526public:
1527 bool runOnMachineFunction(MachineFunction &MF) override;
1528
1529 static char ID;
1530 PostRAMachineSinking() : MachineFunctionPass(ID) {}
1531 StringRef getPassName() const override { return "PostRA Machine Sink"; }
1532
1533 void getAnalysisUsage(AnalysisUsage &AU) const override {
1534 AU.setPreservesCFG();
1535 MachineFunctionPass::getAnalysisUsage(AU);
1536 }
1537
1538 MachineFunctionProperties getRequiredProperties() const override {
1539 return MachineFunctionProperties().set(
1540 MachineFunctionProperties::Property::NoVRegs);
1541 }
1542
1543private:
1544 /// Track which register units have been modified and used.
1545 LiveRegUnits ModifiedRegUnits, UsedRegUnits;
1546
1547 /// Track DBG_VALUEs of (unmodified) register units. Each DBG_VALUE has an
1548 /// entry in this map for each unit it touches. The DBG_VALUE's entry
1549 /// consists of a pointer to the instruction itself, and a vector of registers
1550 /// referred to by the instruction that overlap the key register unit.
1551 DenseMap<unsigned, SmallVector<MIRegs, 2>> SeenDbgInstrs;
1552
1553 /// Sink Copy instructions unused in the same block close to their uses in
1554 /// successors.
1555 bool tryToSinkCopy(MachineBasicBlock &BB, MachineFunction &MF,
1556 const TargetRegisterInfo *TRI, const TargetInstrInfo *TII);
1557};
1558} // namespace
1559
1560char PostRAMachineSinking::ID = 0;
1561char &llvm::PostRAMachineSinkingID = PostRAMachineSinking::ID;
1562
1563INITIALIZE_PASS(PostRAMachineSinking, "postra-machine-sink",static void *initializePostRAMachineSinkingPassOnce(PassRegistry
&Registry) { PassInfo *PI = new PassInfo( "PostRA Machine Sink"
, "postra-machine-sink", &PostRAMachineSinking::ID, PassInfo
::NormalCtor_t(callDefaultCtor<PostRAMachineSinking>), false
, false); Registry.registerPass(*PI, true); return PI; } static
llvm::once_flag InitializePostRAMachineSinkingPassFlag; void
llvm::initializePostRAMachineSinkingPass(PassRegistry &Registry
) { llvm::call_once(InitializePostRAMachineSinkingPassFlag, initializePostRAMachineSinkingPassOnce
, std::ref(Registry)); }
1564 "PostRA Machine Sink", false, false)static void *initializePostRAMachineSinkingPassOnce(PassRegistry
&Registry) { PassInfo *PI = new PassInfo( "PostRA Machine Sink"
, "postra-machine-sink", &PostRAMachineSinking::ID, PassInfo
::NormalCtor_t(callDefaultCtor<PostRAMachineSinking>), false
, false); Registry.registerPass(*PI, true); return PI; } static
llvm::once_flag InitializePostRAMachineSinkingPassFlag; void
llvm::initializePostRAMachineSinkingPass(PassRegistry &Registry
) { llvm::call_once(InitializePostRAMachineSinkingPassFlag, initializePostRAMachineSinkingPassOnce
, std::ref(Registry)); }
1565
1566static bool aliasWithRegsInLiveIn(MachineBasicBlock &MBB, unsigned Reg,
1567 const TargetRegisterInfo *TRI) {
1568 LiveRegUnits LiveInRegUnits(*TRI);
1569 LiveInRegUnits.addLiveIns(MBB);
1570 return !LiveInRegUnits.available(Reg);
1571}
1572
1573static MachineBasicBlock *
1574getSingleLiveInSuccBB(MachineBasicBlock &CurBB,
1575 const SmallPtrSetImpl<MachineBasicBlock *> &SinkableBBs,
1576 unsigned Reg, const TargetRegisterInfo *TRI) {
1577 // Try to find a single sinkable successor in which Reg is live-in.
1578 MachineBasicBlock *BB = nullptr;
1579 for (auto *SI : SinkableBBs) {
1580 if (aliasWithRegsInLiveIn(*SI, Reg, TRI)) {
1581 // If BB is set here, Reg is live-in to at least two sinkable successors,
1582 // so quit.
1583 if (BB)
1584 return nullptr;
1585 BB = SI;
1586 }
1587 }
1588 // Reg is not live-in to any sinkable successors.
1589 if (!BB)
1590 return nullptr;
1591
1592 // Check if any register aliased with Reg is live-in in other successors.
1593 for (auto *SI : CurBB.successors()) {
1594 if (!SinkableBBs.count(SI) && aliasWithRegsInLiveIn(*SI, Reg, TRI))
1595 return nullptr;
1596 }
1597 return BB;
1598}
1599
1600static MachineBasicBlock *
1601getSingleLiveInSuccBB(MachineBasicBlock &CurBB,
1602 const SmallPtrSetImpl<MachineBasicBlock *> &SinkableBBs,
1603 ArrayRef<unsigned> DefedRegsInCopy,
1604 const TargetRegisterInfo *TRI) {
1605 MachineBasicBlock *SingleBB = nullptr;
1606 for (auto DefReg : DefedRegsInCopy) {
1607 MachineBasicBlock *BB =
1608 getSingleLiveInSuccBB(CurBB, SinkableBBs, DefReg, TRI);
1609 if (!BB || (SingleBB && SingleBB != BB))
1610 return nullptr;
1611 SingleBB = BB;
1612 }
1613 return SingleBB;
1614}
1615
1616static void clearKillFlags(MachineInstr *MI, MachineBasicBlock &CurBB,
1617 SmallVectorImpl<unsigned> &UsedOpsInCopy,
1618 LiveRegUnits &UsedRegUnits,
1619 const TargetRegisterInfo *TRI) {
1620 for (auto U : UsedOpsInCopy) {
1621 MachineOperand &MO = MI->getOperand(U);
1622 Register SrcReg = MO.getReg();
1623 if (!UsedRegUnits.available(SrcReg)) {
1624 MachineBasicBlock::iterator NI = std::next(MI->getIterator());
1625 for (MachineInstr &UI : make_range(NI, CurBB.end())) {
1626 if (UI.killsRegister(SrcReg, TRI)) {
1627 UI.clearRegisterKills(SrcReg, TRI);
1628 MO.setIsKill(true);
1629 break;
1630 }
1631 }
1632 }
1633 }
1634}
1635
1636static void updateLiveIn(MachineInstr *MI, MachineBasicBlock *SuccBB,
1637 SmallVectorImpl<unsigned> &UsedOpsInCopy,
1638 SmallVectorImpl<unsigned> &DefedRegsInCopy) {
1639 MachineFunction &MF = *SuccBB->getParent();
1640 const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
1641 for (unsigned DefReg : DefedRegsInCopy)
1642 for (MCSubRegIterator S(DefReg, TRI, true); S.isValid(); ++S)
1643 SuccBB->removeLiveIn(*S);
1644 for (auto U : UsedOpsInCopy) {
1645 Register SrcReg = MI->getOperand(U).getReg();
1646 LaneBitmask Mask;
1647 for (MCRegUnitMaskIterator S(SrcReg, TRI); S.isValid(); ++S) {
1648 Mask |= (*S).second;
1649 }
1650 SuccBB->addLiveIn(SrcReg, Mask.any() ? Mask : LaneBitmask::getAll());
1651 }
1652 SuccBB->sortUniqueLiveIns();
1653}
1654
1655static bool hasRegisterDependency(MachineInstr *MI,
1656 SmallVectorImpl<unsigned> &UsedOpsInCopy,
1657 SmallVectorImpl<unsigned> &DefedRegsInCopy,
1658 LiveRegUnits &ModifiedRegUnits,
1659 LiveRegUnits &UsedRegUnits) {
1660 bool HasRegDependency = false;
1661 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
1662 MachineOperand &MO = MI->getOperand(i);
1663 if (!MO.isReg())
1664 continue;
1665 Register Reg = MO.getReg();
1666 if (!Reg)
1667 continue;
1668 if (MO.isDef()) {
1669 if (!ModifiedRegUnits.available(Reg) || !UsedRegUnits.available(Reg)) {
1670 HasRegDependency = true;
1671 break;
1672 }
1673 DefedRegsInCopy.push_back(Reg);
1674
1675 // FIXME: instead of isUse(), readsReg() would be a better fix here,
1676 // For example, we can ignore modifications in reg with undef. However,
1677 // it's not perfectly clear if skipping the internal read is safe in all
1678 // other targets.
1679 } else if (MO.isUse()) {
1680 if (!ModifiedRegUnits.available(Reg)) {
1681 HasRegDependency = true;
1682 break;
1683 }
1684 UsedOpsInCopy.push_back(i);
1685 }
1686 }
1687 return HasRegDependency;
1688}
1689
1690static SmallSet<MCRegister, 4> getRegUnits(MCRegister Reg,
1691 const TargetRegisterInfo *TRI) {
1692 SmallSet<MCRegister, 4> RegUnits;
1693 for (auto RI = MCRegUnitIterator(Reg, TRI); RI.isValid(); ++RI)
1694 RegUnits.insert(*RI);
1695 return RegUnits;
1696}
1697
1698bool PostRAMachineSinking::tryToSinkCopy(MachineBasicBlock &CurBB,
1699 MachineFunction &MF,
1700 const TargetRegisterInfo *TRI,
1701 const TargetInstrInfo *TII) {
1702 SmallPtrSet<MachineBasicBlock *, 2> SinkableBBs;
1703 // FIXME: For now, we sink only to a successor which has a single predecessor
1704 // so that we can directly sink COPY instructions to the successor without
1705 // adding any new block or branch instruction.
1706 for (MachineBasicBlock *SI : CurBB.successors())
1707 if (!SI->livein_empty() && SI->pred_size() == 1)
1708 SinkableBBs.insert(SI);
1709
1710 if (SinkableBBs.empty())
1711 return false;
1712
1713 bool Changed = false;
1714
1715 // Track which registers have been modified and used between the end of the
1716 // block and the current instruction.
1717 ModifiedRegUnits.clear();
1718 UsedRegUnits.clear();
1719 SeenDbgInstrs.clear();
1720
1721 for (auto I = CurBB.rbegin(), E = CurBB.rend(); I != E;) {
1722 MachineInstr *MI = &*I;
1723 ++I;
1724
1725 // Track the operand index for use in Copy.
1726 SmallVector<unsigned, 2> UsedOpsInCopy;
1727 // Track the register number defed in Copy.
1728 SmallVector<unsigned, 2> DefedRegsInCopy;
1729
1730 // We must sink this DBG_VALUE if its operand is sunk. To avoid searching
1731 // for DBG_VALUEs later, record them when they're encountered.
1732 if (MI->isDebugValue()) {
1733 SmallDenseMap<MCRegister, SmallVector<unsigned, 2>, 4> MIUnits;
1734 bool IsValid = true;
1735 for (MachineOperand &MO : MI->debug_operands()) {
1736 if (MO.isReg() && Register::isPhysicalRegister(MO.getReg())) {
1737 // Bail if we can already tell the sink would be rejected, rather
1738 // than needlessly accumulating lots of DBG_VALUEs.
1739 if (hasRegisterDependency(MI, UsedOpsInCopy, DefedRegsInCopy,
1740 ModifiedRegUnits, UsedRegUnits)) {
1741 IsValid = false;
1742 break;
1743 }
1744
1745 // Record debug use of each reg unit.
1746 SmallSet<MCRegister, 4> RegUnits = getRegUnits(MO.getReg(), TRI);
1747 for (MCRegister Reg : RegUnits)
1748 MIUnits[Reg].push_back(MO.getReg());
1749 }
1750 }
1751 if (IsValid) {
1752 for (auto RegOps : MIUnits)
1753 SeenDbgInstrs[RegOps.first].push_back({MI, RegOps.second});
1754 }
1755 continue;
1756 }
1757
1758 if (MI->isDebugOrPseudoInstr())
1759 continue;
1760
1761 // Do not move any instruction across function call.
1762 if (MI->isCall())
1763 return false;
1764
1765 if (!MI->isCopy() || !MI->getOperand(0).isRenamable()) {
1766 LiveRegUnits::accumulateUsedDefed(*MI, ModifiedRegUnits, UsedRegUnits,
1767 TRI);
1768 continue;
1769 }
1770
1771 // Don't sink the COPY if it would violate a register dependency.
1772 if (hasRegisterDependency(MI, UsedOpsInCopy, DefedRegsInCopy,
1773 ModifiedRegUnits, UsedRegUnits)) {
1774 LiveRegUnits::accumulateUsedDefed(*MI, ModifiedRegUnits, UsedRegUnits,
1775 TRI);
1776 continue;
1777 }
1778 assert((!UsedOpsInCopy.empty() && !DefedRegsInCopy.empty()) &&((void)0)
1779 "Unexpect SrcReg or DefReg")((void)0);
1780 MachineBasicBlock *SuccBB =
1781 getSingleLiveInSuccBB(CurBB, SinkableBBs, DefedRegsInCopy, TRI);
1782 // Don't sink if we cannot find a single sinkable successor in which Reg
1783 // is live-in.
1784 if (!SuccBB) {
1785 LiveRegUnits::accumulateUsedDefed(*MI, ModifiedRegUnits, UsedRegUnits,
1786 TRI);
1787 continue;
1788 }
1789 assert((SuccBB->pred_size() == 1 && *SuccBB->pred_begin() == &CurBB) &&((void)0)
1790 "Unexpected predecessor")((void)0);
1791
1792 // Collect DBG_VALUEs that must sink with this copy. We've previously
1793 // recorded which reg units that DBG_VALUEs read, if this instruction
1794 // writes any of those units then the corresponding DBG_VALUEs must sink.
1795 MapVector<MachineInstr *, MIRegs::second_type> DbgValsToSinkMap;
1796 for (auto &MO : MI->operands()) {
1797 if (!MO.isReg() || !MO.isDef())
1798 continue;
1799
1800 SmallSet<MCRegister, 4> Units = getRegUnits(MO.getReg(), TRI);
1801 for (MCRegister Reg : Units) {
1802 for (auto MIRegs : SeenDbgInstrs.lookup(Reg)) {
1803 auto &Regs = DbgValsToSinkMap[MIRegs.first];
1804 for (unsigned Reg : MIRegs.second)
1805 Regs.push_back(Reg);
1806 }
1807 }
1808 }
1809 SmallVector<MIRegs, 4> DbgValsToSink(DbgValsToSinkMap.begin(),
1810 DbgValsToSinkMap.end());
1811
1812 // Clear the kill flag if SrcReg is killed between MI and the end of the
1813 // block.
1814 clearKillFlags(MI, CurBB, UsedOpsInCopy, UsedRegUnits, TRI);
1815 MachineBasicBlock::iterator InsertPos = SuccBB->getFirstNonPHI();
1816 performSink(*MI, *SuccBB, InsertPos, DbgValsToSink);
1817 updateLiveIn(MI, SuccBB, UsedOpsInCopy, DefedRegsInCopy);
1818
1819 Changed = true;
1820 ++NumPostRACopySink;
1821 }
1822 return Changed;
1823}
1824
1825bool PostRAMachineSinking::runOnMachineFunction(MachineFunction &MF) {
1826 if (skipFunction(MF.getFunction()))
1827 return false;
1828
1829 bool Changed = false;
1830 const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
1831 const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
1832
1833 ModifiedRegUnits.init(*TRI);
1834 UsedRegUnits.init(*TRI);
1835 for (auto &BB : MF)
1836 Changed |= tryToSinkCopy(BB, MF, TRI, TII);
1837
1838 return Changed;
1839}

/usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/CodeGen/MachineDominators.h

1//==- llvm/CodeGen/MachineDominators.h - Machine Dom Calculation -*- C++ -*-==//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines classes mirroring those in llvm/Analysis/Dominators.h,
10// but for target-specific code rather than target-independent IR.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CODEGEN_MACHINEDOMINATORS_H
15#define LLVM_CODEGEN_MACHINEDOMINATORS_H
16
17#include "llvm/ADT/SmallSet.h"
18#include "llvm/ADT/SmallVector.h"
19#include "llvm/CodeGen/MachineBasicBlock.h"
20#include "llvm/CodeGen/MachineFunctionPass.h"
21#include "llvm/CodeGen/MachineInstr.h"
22#include "llvm/Support/GenericDomTree.h"
23#include "llvm/Support/GenericDomTreeConstruction.h"
24#include <cassert>
25#include <memory>
26
27namespace llvm {
28
29template <>
30inline void DominatorTreeBase<MachineBasicBlock, false>::addRoot(
31 MachineBasicBlock *MBB) {
32 this->Roots.push_back(MBB);
33}
34
35extern template class DomTreeNodeBase<MachineBasicBlock>;
36extern template class DominatorTreeBase<MachineBasicBlock, false>; // DomTree
37extern template class DominatorTreeBase<MachineBasicBlock, true>; // PostDomTree
38
39using MachineDomTreeNode = DomTreeNodeBase<MachineBasicBlock>;
40
41//===-------------------------------------
42/// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to
43/// compute a normal dominator tree.
44///
45class MachineDominatorTree : public MachineFunctionPass {
46 using DomTreeT = DomTreeBase<MachineBasicBlock>;
47
48 /// Helper structure used to hold all the basic blocks
49 /// involved in the split of a critical edge.
50 struct CriticalEdge {
51 MachineBasicBlock *FromBB;
52 MachineBasicBlock *ToBB;
53 MachineBasicBlock *NewBB;
54 };
55
56 /// Pile up all the critical edges to be split.
57 /// The splitting of a critical edge is local and thus, it is possible
58 /// to apply several of those changes at the same time.
59 mutable SmallVector<CriticalEdge, 32> CriticalEdgesToSplit;
60
61 /// Remember all the basic blocks that are inserted during
62 /// edge splitting.
63 /// Invariant: NewBBs == all the basic blocks contained in the NewBB
64 /// field of all the elements of CriticalEdgesToSplit.
65 /// I.e., forall elt in CriticalEdgesToSplit, it exists BB in NewBBs
66 /// such as BB == elt.NewBB.
67 mutable SmallSet<MachineBasicBlock *, 32> NewBBs;
68
69 /// The DominatorTreeBase that is used to compute a normal dominator tree.
70 std::unique_ptr<DomTreeT> DT;
71
72 /// Apply all the recorded critical edges to the DT.
73 /// This updates the underlying DT information in a way that uses
74 /// the fast query path of DT as much as possible.
75 ///
76 /// \post CriticalEdgesToSplit.empty().
77 void applySplitCriticalEdges() const;
78
79public:
80 static char ID; // Pass ID, replacement for typeid
81
82 MachineDominatorTree();
83 explicit MachineDominatorTree(MachineFunction &MF) : MachineFunctionPass(ID) {
84 calculate(MF);
85 }
86
87 DomTreeT &getBase() {
88 if (!DT) DT.reset(new DomTreeT());
89 applySplitCriticalEdges();
90 return *DT;
91 }
92
93 void getAnalysisUsage(AnalysisUsage &AU) const override;
94
95 MachineBasicBlock *getRoot() const {
96 applySplitCriticalEdges();
97 return DT->getRoot();
98 }
99
100 MachineDomTreeNode *getRootNode() const {
101 applySplitCriticalEdges();
102 return DT->getRootNode();
103 }
104
105 bool runOnMachineFunction(MachineFunction &F) override;
106
107 void calculate(MachineFunction &F);
108
109 bool dominates(const MachineDomTreeNode *A,
110 const MachineDomTreeNode *B) const {
111 applySplitCriticalEdges();
112 return DT->dominates(A, B);
113 }
114
115 bool dominates(const MachineBasicBlock *A, const MachineBasicBlock *B) const {
116 applySplitCriticalEdges();
117 return DT->dominates(A, B);
118 }
119
120 // dominates - Return true if A dominates B. This performs the
121 // special checks necessary if A and B are in the same basic block.
122 bool dominates(const MachineInstr *A, const MachineInstr *B) const {
123 applySplitCriticalEdges();
124 const MachineBasicBlock *BBA = A->getParent(), *BBB = B->getParent();
125 if (BBA != BBB) return DT->dominates(BBA, BBB);
126
127 // Loop through the basic block until we find A or B.
128 MachineBasicBlock::const_iterator I = BBA->begin();
129 for (; &*I != A && &*I != B; ++I)
130 /*empty*/ ;
131
132 return &*I == A;
133 }
134
135 bool properlyDominates(const MachineDomTreeNode *A,
136 const MachineDomTreeNode *B) const {
137 applySplitCriticalEdges();
138 return DT->properlyDominates(A, B);
139 }
140
141 bool properlyDominates(const MachineBasicBlock *A,
142 const MachineBasicBlock *B) const {
143 applySplitCriticalEdges();
144 return DT->properlyDominates(A, B);
145 }
146
147 /// findNearestCommonDominator - Find nearest common dominator basic block
148 /// for basic block A and B. If there is no such block then return NULL.
149 MachineBasicBlock *findNearestCommonDominator(MachineBasicBlock *A,
150 MachineBasicBlock *B) {
151 applySplitCriticalEdges();
152 return DT->findNearestCommonDominator(A, B);
33
Calling 'DominatorTreeBase::findNearestCommonDominator'
153 }
154
155 MachineDomTreeNode *operator[](MachineBasicBlock *BB) const {
156 applySplitCriticalEdges();
157 return DT->getNode(BB);
158 }
159
160 /// getNode - return the (Post)DominatorTree node for the specified basic
161 /// block. This is the same as using operator[] on this class.
162 ///
163 MachineDomTreeNode *getNode(MachineBasicBlock *BB) const {
164 applySplitCriticalEdges();
165 return DT->getNode(BB);
166 }
167
168 /// addNewBlock - Add a new node to the dominator tree information. This
169 /// creates a new node as a child of DomBB dominator node,linking it into
170 /// the children list of the immediate dominator.
171 MachineDomTreeNode *addNewBlock(MachineBasicBlock *BB,
172 MachineBasicBlock *DomBB) {
173 applySplitCriticalEdges();
174 return DT->addNewBlock(BB, DomBB);
175 }
176
177 /// changeImmediateDominator - This method is used to update the dominator
178 /// tree information when a node's immediate dominator changes.
179 ///
180 void changeImmediateDominator(MachineBasicBlock *N,
181 MachineBasicBlock *NewIDom) {
182 applySplitCriticalEdges();
183 DT->changeImmediateDominator(N, NewIDom);
184 }
185
186 void changeImmediateDominator(MachineDomTreeNode *N,
187 MachineDomTreeNode *NewIDom) {
188 applySplitCriticalEdges();
189 DT->changeImmediateDominator(N, NewIDom);
190 }
191
192 /// eraseNode - Removes a node from the dominator tree. Block must not
193 /// dominate any other blocks. Removes node from its immediate dominator's
194 /// children list. Deletes dominator node associated with basic block BB.
195 void eraseNode(MachineBasicBlock *BB) {
196 applySplitCriticalEdges();
197 DT->eraseNode(BB);
198 }
199
200 /// splitBlock - BB is split and now it has one successor. Update dominator
201 /// tree to reflect this change.
202 void splitBlock(MachineBasicBlock* NewBB) {
203 applySplitCriticalEdges();
204 DT->splitBlock(NewBB);
205 }
206
207 /// isReachableFromEntry - Return true if A is dominated by the entry
208 /// block of the function containing it.
209 bool isReachableFromEntry(const MachineBasicBlock *A) {
210 applySplitCriticalEdges();
211 return DT->isReachableFromEntry(A);
212 }
213
214 void releaseMemory() override;
215
216 void verifyAnalysis() const override;
217
218 void print(raw_ostream &OS, const Module*) const override;
219
220 /// Record that the critical edge (FromBB, ToBB) has been
221 /// split with NewBB.
222 /// This is best to use this method instead of directly update the
223 /// underlying information, because this helps mitigating the
224 /// number of time the DT information is invalidated.
225 ///
226 /// \note Do not use this method with regular edges.
227 ///
228 /// \note To benefit from the compile time improvement incurred by this
229 /// method, the users of this method have to limit the queries to the DT
230 /// interface between two edges splitting. In other words, they have to
231 /// pack the splitting of critical edges as much as possible.
232 void recordSplitCriticalEdge(MachineBasicBlock *FromBB,
233 MachineBasicBlock *ToBB,
234 MachineBasicBlock *NewBB) {
235 bool Inserted = NewBBs.insert(NewBB).second;
236 (void)Inserted;
237 assert(Inserted &&((void)0)
238 "A basic block inserted via edge splitting cannot appear twice")((void)0);
239 CriticalEdgesToSplit.push_back({FromBB, ToBB, NewBB});
240 }
241};
242
243//===-------------------------------------
244/// DominatorTree GraphTraits specialization so the DominatorTree can be
245/// iterable by generic graph iterators.
246///
247
248template <class Node, class ChildIterator>
249struct MachineDomTreeGraphTraitsBase {
250 using NodeRef = Node *;
251 using ChildIteratorType = ChildIterator;
252
253 static NodeRef getEntryNode(NodeRef N) { return N; }
254 static ChildIteratorType child_begin(NodeRef N) { return N->begin(); }
255 static ChildIteratorType child_end(NodeRef N) { return N->end(); }
256};
257
258template <class T> struct GraphTraits;
259
260template <>
261struct GraphTraits<MachineDomTreeNode *>
262 : public MachineDomTreeGraphTraitsBase<MachineDomTreeNode,
263 MachineDomTreeNode::const_iterator> {
264};
265
266template <>
267struct GraphTraits<const MachineDomTreeNode *>
268 : public MachineDomTreeGraphTraitsBase<const MachineDomTreeNode,
269 MachineDomTreeNode::const_iterator> {
270};
271
272template <> struct GraphTraits<MachineDominatorTree*>
273 : public GraphTraits<MachineDomTreeNode *> {
274 static NodeRef getEntryNode(MachineDominatorTree *DT) {
275 return DT->getRootNode();
276 }
277};
278
279} // end namespace llvm
280
281#endif // LLVM_CODEGEN_MACHINEDOMINATORS_H

/usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Support/GenericDomTree.h

1//===- GenericDomTree.h - Generic dominator trees for graphs ----*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8/// \file
9///
10/// This file defines a set of templates that efficiently compute a dominator
11/// tree over a generic graph. This is used typically in LLVM for fast
12/// dominance queries on the CFG, but is fully generic w.r.t. the underlying
13/// graph types.
14///
15/// Unlike ADT/* graph algorithms, generic dominator tree has more requirements
16/// on the graph's NodeRef. The NodeRef should be a pointer and,
17/// NodeRef->getParent() must return the parent node that is also a pointer.
18///
19/// FIXME: Maybe GenericDomTree needs a TreeTraits, instead of GraphTraits.
20///
21//===----------------------------------------------------------------------===//
22
23#ifndef LLVM_SUPPORT_GENERICDOMTREE_H
24#define LLVM_SUPPORT_GENERICDOMTREE_H
25
26#include "llvm/ADT/DenseMap.h"
27#include "llvm/ADT/GraphTraits.h"
28#include "llvm/ADT/STLExtras.h"
29#include "llvm/ADT/SmallPtrSet.h"
30#include "llvm/ADT/SmallVector.h"
31#include "llvm/Support/CFGDiff.h"
32#include "llvm/Support/CFGUpdate.h"
33#include "llvm/Support/raw_ostream.h"
34#include <algorithm>
35#include <cassert>
36#include <cstddef>
37#include <iterator>
38#include <memory>
39#include <type_traits>
40#include <utility>
41
42namespace llvm {
43
44template <typename NodeT, bool IsPostDom>
45class DominatorTreeBase;
46
47namespace DomTreeBuilder {
48template <typename DomTreeT>
49struct SemiNCAInfo;
50} // namespace DomTreeBuilder
51
52/// Base class for the actual dominator tree node.
53template <class NodeT> class DomTreeNodeBase {
54 friend class PostDominatorTree;
55 friend class DominatorTreeBase<NodeT, false>;
56 friend class DominatorTreeBase<NodeT, true>;
57 friend struct DomTreeBuilder::SemiNCAInfo<DominatorTreeBase<NodeT, false>>;
58 friend struct DomTreeBuilder::SemiNCAInfo<DominatorTreeBase<NodeT, true>>;
59
60 NodeT *TheBB;
61 DomTreeNodeBase *IDom;
62 unsigned Level;
63 SmallVector<DomTreeNodeBase *, 4> Children;
64 mutable unsigned DFSNumIn = ~0;
65 mutable unsigned DFSNumOut = ~0;
66
67 public:
68 DomTreeNodeBase(NodeT *BB, DomTreeNodeBase *iDom)
69 : TheBB(BB), IDom(iDom), Level(IDom ? IDom->Level + 1 : 0) {}
70
71 using iterator = typename SmallVector<DomTreeNodeBase *, 4>::iterator;
72 using const_iterator =
73 typename SmallVector<DomTreeNodeBase *, 4>::const_iterator;
74
75 iterator begin() { return Children.begin(); }
76 iterator end() { return Children.end(); }
77 const_iterator begin() const { return Children.begin(); }
78 const_iterator end() const { return Children.end(); }
79
80 DomTreeNodeBase *const &back() const { return Children.back(); }
81 DomTreeNodeBase *&back() { return Children.back(); }
82
83 iterator_range<iterator> children() { return make_range(begin(), end()); }
84 iterator_range<const_iterator> children() const {
85 return make_range(begin(), end());
86 }
87
88 NodeT *getBlock() const { return TheBB; }
89 DomTreeNodeBase *getIDom() const { return IDom; }
90 unsigned getLevel() const { return Level; }
91
92 std::unique_ptr<DomTreeNodeBase> addChild(
93 std::unique_ptr<DomTreeNodeBase> C) {
94 Children.push_back(C.get());
95 return C;
96 }
97
98 bool isLeaf() const { return Children.empty(); }
99 size_t getNumChildren() const { return Children.size(); }
100
101 void clearAllChildren() { Children.clear(); }
102
103 bool compare(const DomTreeNodeBase *Other) const {
104 if (getNumChildren() != Other->getNumChildren())
105 return true;
106
107 if (Level != Other->Level) return true;
108
109 SmallPtrSet<const NodeT *, 4> OtherChildren;
110 for (const DomTreeNodeBase *I : *Other) {
111 const NodeT *Nd = I->getBlock();
112 OtherChildren.insert(Nd);
113 }
114
115 for (const DomTreeNodeBase *I : *this) {
116 const NodeT *N = I->getBlock();
117 if (OtherChildren.count(N) == 0)
118 return true;
119 }
120 return false;
121 }
122
123 void setIDom(DomTreeNodeBase *NewIDom) {
124 assert(IDom && "No immediate dominator?")((void)0);
125 if (IDom == NewIDom) return;
126
127 auto I = find(IDom->Children, this);
128 assert(I != IDom->Children.end() &&((void)0)
129 "Not in immediate dominator children set!")((void)0);
130 // I am no longer your child...
131 IDom->Children.erase(I);
132
133 // Switch to new dominator
134 IDom = NewIDom;
135 IDom->Children.push_back(this);
136
137 UpdateLevel();
138 }
139
140 /// getDFSNumIn/getDFSNumOut - These return the DFS visitation order for nodes
141 /// in the dominator tree. They are only guaranteed valid if
142 /// updateDFSNumbers() has been called.
143 unsigned getDFSNumIn() const { return DFSNumIn; }
144 unsigned getDFSNumOut() const { return DFSNumOut; }
145
146private:
147 // Return true if this node is dominated by other. Use this only if DFS info
148 // is valid.
149 bool DominatedBy(const DomTreeNodeBase *other) const {
150 return this->DFSNumIn >= other->DFSNumIn &&
151 this->DFSNumOut <= other->DFSNumOut;
152 }
153
154 void UpdateLevel() {
155 assert(IDom)((void)0);
156 if (Level == IDom->Level + 1) return;
157
158 SmallVector<DomTreeNodeBase *, 64> WorkStack = {this};
159
160 while (!WorkStack.empty()) {
161 DomTreeNodeBase *Current = WorkStack.pop_back_val();
162 Current->Level = Current->IDom->Level + 1;
163
164 for (DomTreeNodeBase *C : *Current) {
165 assert(C->IDom)((void)0);
166 if (C->Level != C->IDom->Level + 1) WorkStack.push_back(C);
167 }
168 }
169 }
170};
171
172template <class NodeT>
173raw_ostream &operator<<(raw_ostream &O, const DomTreeNodeBase<NodeT> *Node) {
174 if (Node->getBlock())
175 Node->getBlock()->printAsOperand(O, false);
176 else
177 O << " <<exit node>>";
178
179 O << " {" << Node->getDFSNumIn() << "," << Node->getDFSNumOut() << "} ["
180 << Node->getLevel() << "]\n";
181
182 return O;
183}
184
185template <class NodeT>
186void PrintDomTree(const DomTreeNodeBase<NodeT> *N, raw_ostream &O,
187 unsigned Lev) {
188 O.indent(2 * Lev) << "[" << Lev << "] " << N;
189 for (typename DomTreeNodeBase<NodeT>::const_iterator I = N->begin(),
190 E = N->end();
191 I != E; ++I)
192 PrintDomTree<NodeT>(*I, O, Lev + 1);
193}
194
195namespace DomTreeBuilder {
196// The routines below are provided in a separate header but referenced here.
197template <typename DomTreeT>
198void Calculate(DomTreeT &DT);
199
200template <typename DomTreeT>
201void CalculateWithUpdates(DomTreeT &DT,
202 ArrayRef<typename DomTreeT::UpdateType> Updates);
203
204template <typename DomTreeT>
205void InsertEdge(DomTreeT &DT, typename DomTreeT::NodePtr From,
206 typename DomTreeT::NodePtr To);
207
208template <typename DomTreeT>
209void DeleteEdge(DomTreeT &DT, typename DomTreeT::NodePtr From,
210 typename DomTreeT::NodePtr To);
211
212template <typename DomTreeT>
213void ApplyUpdates(DomTreeT &DT,
214 GraphDiff<typename DomTreeT::NodePtr,
215 DomTreeT::IsPostDominator> &PreViewCFG,
216 GraphDiff<typename DomTreeT::NodePtr,
217 DomTreeT::IsPostDominator> *PostViewCFG);
218
219template <typename DomTreeT>
220bool Verify(const DomTreeT &DT, typename DomTreeT::VerificationLevel VL);
221} // namespace DomTreeBuilder
222
223/// Core dominator tree base class.
224///
225/// This class is a generic template over graph nodes. It is instantiated for
226/// various graphs in the LLVM IR or in the code generator.
227template <typename NodeT, bool IsPostDom>
228class DominatorTreeBase {
229 public:
230 static_assert(std::is_pointer<typename GraphTraits<NodeT *>::NodeRef>::value,
231 "Currently DominatorTreeBase supports only pointer nodes");
232 using NodeType = NodeT;
233 using NodePtr = NodeT *;
234 using ParentPtr = decltype(std::declval<NodeT *>()->getParent());
235 static_assert(std::is_pointer<ParentPtr>::value,
236 "Currently NodeT's parent must be a pointer type");
237 using ParentType = std::remove_pointer_t<ParentPtr>;
238 static constexpr bool IsPostDominator = IsPostDom;
239
240 using UpdateType = cfg::Update<NodePtr>;
241 using UpdateKind = cfg::UpdateKind;
242 static constexpr UpdateKind Insert = UpdateKind::Insert;
243 static constexpr UpdateKind Delete = UpdateKind::Delete;
244
245 enum class VerificationLevel { Fast, Basic, Full };
246
247protected:
248 // Dominators always have a single root, postdominators can have more.
249 SmallVector<NodeT *, IsPostDom ? 4 : 1> Roots;
250
251 using DomTreeNodeMapType =
252 DenseMap<NodeT *, std::unique_ptr<DomTreeNodeBase<NodeT>>>;
253 DomTreeNodeMapType DomTreeNodes;
254 DomTreeNodeBase<NodeT> *RootNode = nullptr;
255 ParentPtr Parent = nullptr;
256
257 mutable bool DFSInfoValid = false;
258 mutable unsigned int SlowQueries = 0;
259
260 friend struct DomTreeBuilder::SemiNCAInfo<DominatorTreeBase>;
261
262 public:
263 DominatorTreeBase() {}
264
265 DominatorTreeBase(DominatorTreeBase &&Arg)
266 : Roots(std::move(Arg.Roots)),
267 DomTreeNodes(std::move(Arg.DomTreeNodes)),
268 RootNode(Arg.RootNode),
269 Parent(Arg.Parent),
270 DFSInfoValid(Arg.DFSInfoValid),
271 SlowQueries(Arg.SlowQueries) {
272 Arg.wipe();
273 }
274
275 DominatorTreeBase &operator=(DominatorTreeBase &&RHS) {
276 Roots = std::move(RHS.Roots);
277 DomTreeNodes = std::move(RHS.DomTreeNodes);
278 RootNode = RHS.RootNode;
279 Parent = RHS.Parent;
280 DFSInfoValid = RHS.DFSInfoValid;
281 SlowQueries = RHS.SlowQueries;
282 RHS.wipe();
283 return *this;
284 }
285
286 DominatorTreeBase(const DominatorTreeBase &) = delete;
287 DominatorTreeBase &operator=(const DominatorTreeBase &) = delete;
288
289 /// Iteration over roots.
290 ///
291 /// This may include multiple blocks if we are computing post dominators.
292 /// For forward dominators, this will always be a single block (the entry
293 /// block).
294 using root_iterator = typename SmallVectorImpl<NodeT *>::iterator;
295 using const_root_iterator = typename SmallVectorImpl<NodeT *>::const_iterator;
296
297 root_iterator root_begin() { return Roots.begin(); }
298 const_root_iterator root_begin() const { return Roots.begin(); }
299 root_iterator root_end() { return Roots.end(); }
300 const_root_iterator root_end() const { return Roots.end(); }
301
302 size_t root_size() const { return Roots.size(); }
303
304 iterator_range<root_iterator> roots() {
305 return make_range(root_begin(), root_end());
306 }
307 iterator_range<const_root_iterator> roots() const {
308 return make_range(root_begin(), root_end());
309 }
310
311 /// isPostDominator - Returns true if analysis based of postdoms
312 ///
313 bool isPostDominator() const { return IsPostDominator; }
35
Returning zero (loaded from 'IsPostDominator'), which participates in a condition later
314
315 /// compare - Return false if the other dominator tree base matches this
316 /// dominator tree base. Otherwise return true.
317 bool compare(const DominatorTreeBase &Other) const {
318 if (Parent != Other.Parent) return true;
319
320 if (Roots.size() != Other.Roots.size())
321 return true;
322
323 if (!std::is_permutation(Roots.begin(), Roots.end(), Other.Roots.begin()))
324 return true;
325
326 const DomTreeNodeMapType &OtherDomTreeNodes = Other.DomTreeNodes;
327 if (DomTreeNodes.size() != OtherDomTreeNodes.size())
328 return true;
329
330 for (const auto &DomTreeNode : DomTreeNodes) {
331 NodeT *BB = DomTreeNode.first;
332 typename DomTreeNodeMapType::const_iterator OI =
333 OtherDomTreeNodes.find(BB);
334 if (OI == OtherDomTreeNodes.end())
335 return true;
336
337 DomTreeNodeBase<NodeT> &MyNd = *DomTreeNode.second;
338 DomTreeNodeBase<NodeT> &OtherNd = *OI->second;
339
340 if (MyNd.compare(&OtherNd))
341 return true;
342 }
343
344 return false;
345 }
346
347 /// getNode - return the (Post)DominatorTree node for the specified basic
348 /// block. This is the same as using operator[] on this class. The result
349 /// may (but is not required to) be null for a forward (backwards)
350 /// statically unreachable block.
351 DomTreeNodeBase<NodeT> *getNode(const NodeT *BB) const {
352 auto I = DomTreeNodes.find(BB);
353 if (I != DomTreeNodes.end())
42
Calling 'operator!='
48
Returning from 'operator!='
49
Taking true branch
354 return I->second.get();
50
Returning pointer
355 return nullptr;
356 }
357
358 /// See getNode.
359 DomTreeNodeBase<NodeT> *operator[](const NodeT *BB) const {
360 return getNode(BB);
361 }
362
363 /// getRootNode - This returns the entry node for the CFG of the function. If
364 /// this tree represents the post-dominance relations for a function, however,
365 /// this root may be a node with the block == NULL. This is the case when
366 /// there are multiple exit nodes from a particular function. Consumers of
367 /// post-dominance information must be capable of dealing with this
368 /// possibility.
369 ///
370 DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; }
371 const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; }
372
373 /// Get all nodes dominated by R, including R itself.
374 void getDescendants(NodeT *R, SmallVectorImpl<NodeT *> &Result) const {
375 Result.clear();
376 const DomTreeNodeBase<NodeT> *RN = getNode(R);
377 if (!RN)
378 return; // If R is unreachable, it will not be present in the DOM tree.
379 SmallVector<const DomTreeNodeBase<NodeT> *, 8> WL;
380 WL.push_back(RN);
381
382 while (!WL.empty()) {
383 const DomTreeNodeBase<NodeT> *N = WL.pop_back_val();
384 Result.push_back(N->getBlock());
385 WL.append(N->begin(), N->end());
386 }
387 }
388
389 /// properlyDominates - Returns true iff A dominates B and A != B.
390 /// Note that this is not a constant time operation!
391 ///
392 bool properlyDominates(const DomTreeNodeBase<NodeT> *A,
393 const DomTreeNodeBase<NodeT> *B) const {
394 if (!A || !B)
395 return false;
396 if (A == B)
397 return false;
398 return dominates(A, B);
399 }
400
401 bool properlyDominates(const NodeT *A, const NodeT *B) const;
402
403 /// isReachableFromEntry - Return true if A is dominated by the entry
404 /// block of the function containing it.
405 bool isReachableFromEntry(const NodeT *A) const {
406 assert(!this->isPostDominator() &&((void)0)
407 "This is not implemented for post dominators")((void)0);
408 return isReachableFromEntry(getNode(const_cast<NodeT *>(A)));
409 }
410
411 bool isReachableFromEntry(const DomTreeNodeBase<NodeT> *A) const { return A; }
412
413 /// dominates - Returns true iff A dominates B. Note that this is not a
414 /// constant time operation!
415 ///
416 bool dominates(const DomTreeNodeBase<NodeT> *A,
417 const DomTreeNodeBase<NodeT> *B) const {
418 // A node trivially dominates itself.
419 if (B == A)
420 return true;
421
422 // An unreachable node is dominated by anything.
423 if (!isReachableFromEntry(B))
424 return true;
425
426 // And dominates nothing.
427 if (!isReachableFromEntry(A))
428 return false;
429
430 if (B->getIDom() == A) return true;
431
432 if (A->getIDom() == B) return false;
433
434 // A can only dominate B if it is higher in the tree.
435 if (A->getLevel() >= B->getLevel()) return false;
436
437 // Compare the result of the tree walk and the dfs numbers, if expensive
438 // checks are enabled.
439#ifdef EXPENSIVE_CHECKS
440 assert((!DFSInfoValid ||((void)0)
441 (dominatedBySlowTreeWalk(A, B) == B->DominatedBy(A))) &&((void)0)
442 "Tree walk disagrees with dfs numbers!")((void)0);
443#endif
444
445 if (DFSInfoValid)
446 return B->DominatedBy(A);
447
448 // If we end up with too many slow queries, just update the
449 // DFS numbers on the theory that we are going to keep querying.
450 SlowQueries++;
451 if (SlowQueries > 32) {
452 updateDFSNumbers();
453 return B->DominatedBy(A);
454 }
455
456 return dominatedBySlowTreeWalk(A, B);
457 }
458
459 bool dominates(const NodeT *A, const NodeT *B) const;
460
461 NodeT *getRoot() const {
462 assert(this->Roots.size() == 1 && "Should always have entry node!")((void)0);
463 return this->Roots[0];
464 }
465
466 /// Find nearest common dominator basic block for basic block A and B. A and B
467 /// must have tree nodes.
468 NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) const {
469 assert(A && B && "Pointers are not valid")((void)0);
470 assert(A->getParent() == B->getParent() &&((void)0)
471 "Two blocks are not in same function")((void)0);
472
473 // If either A or B is a entry block then it is nearest common dominator
474 // (for forward-dominators).
475 if (!isPostDominator()) {
34
Calling 'DominatorTreeBase::isPostDominator'
36
Returning from 'DominatorTreeBase::isPostDominator'
37
Taking true branch
476 NodeT &Entry = A->getParent()->front();
477 if (A == &Entry || B == &Entry)
38
Assuming the condition is false
39
Assuming the condition is false
40
Taking false branch
478 return &Entry;
479 }
480
481 DomTreeNodeBase<NodeT> *NodeA = getNode(A);
41
Calling 'DominatorTreeBase::getNode'
51
Returning from 'DominatorTreeBase::getNode'
52
'NodeA' initialized here
482 DomTreeNodeBase<NodeT> *NodeB = getNode(B);
483 assert(NodeA && "A must be in the tree")((void)0);
484 assert(NodeB && "B must be in the tree")((void)0);
485
486 // Use level information to go up the tree until the levels match. Then
487 // continue going up til we arrive at the same node.
488 while (NodeA != NodeB) {
53
Assuming 'NodeA' is equal to 'NodeB'
54
Assuming pointer value is null
55
Loop condition is false. Execution continues on line 494
489 if (NodeA->getLevel() < NodeB->getLevel()) std::swap(NodeA, NodeB);
490
491 NodeA = NodeA->IDom;
492 }
493
494 return NodeA->getBlock();
56
Called C++ object pointer is null
495 }
496
497 const NodeT *findNearestCommonDominator(const NodeT *A,
498 const NodeT *B) const {
499 // Cast away the const qualifiers here. This is ok since
500 // const is re-introduced on the return type.
501 return findNearestCommonDominator(const_cast<NodeT *>(A),
502 const_cast<NodeT *>(B));
503 }
504
505 bool isVirtualRoot(const DomTreeNodeBase<NodeT> *A) const {
506 return isPostDominator() && !A->getBlock();
507 }
508
509 //===--------------------------------------------------------------------===//
510 // API to update (Post)DominatorTree information based on modifications to
511 // the CFG...
512
513 /// Inform the dominator tree about a sequence of CFG edge insertions and
514 /// deletions and perform a batch update on the tree.
515 ///
516 /// This function should be used when there were multiple CFG updates after
517 /// the last dominator tree update. It takes care of performing the updates
518 /// in sync with the CFG and optimizes away the redundant operations that
519 /// cancel each other.
520 /// The functions expects the sequence of updates to be balanced. Eg.:
521 /// - {{Insert, A, B}, {Delete, A, B}, {Insert, A, B}} is fine, because
522 /// logically it results in a single insertions.
523 /// - {{Insert, A, B}, {Insert, A, B}} is invalid, because it doesn't make
524 /// sense to insert the same edge twice.
525 ///
526 /// What's more, the functions assumes that it's safe to ask every node in the
527 /// CFG about its children and inverse children. This implies that deletions
528 /// of CFG edges must not delete the CFG nodes before calling this function.
529 ///
530 /// The applyUpdates function can reorder the updates and remove redundant
531 /// ones internally. The batch updater is also able to detect sequences of
532 /// zero and exactly one update -- it's optimized to do less work in these
533 /// cases.
534 ///
535 /// Note that for postdominators it automatically takes care of applying
536 /// updates on reverse edges internally (so there's no need to swap the
537 /// From and To pointers when constructing DominatorTree::UpdateType).
538 /// The type of updates is the same for DomTreeBase<T> and PostDomTreeBase<T>
539 /// with the same template parameter T.
540 ///
541 /// \param Updates An unordered sequence of updates to perform. The current
542 /// CFG and the reverse of these updates provides the pre-view of the CFG.
543 ///
544 void applyUpdates(ArrayRef<UpdateType> Updates) {
545 GraphDiff<NodePtr, IsPostDominator> PreViewCFG(
546 Updates, /*ReverseApplyUpdates=*/true);
547 DomTreeBuilder::ApplyUpdates(*this, PreViewCFG, nullptr);
548 }
549
550 /// \param Updates An unordered sequence of updates to perform. The current
551 /// CFG and the reverse of these updates provides the pre-view of the CFG.
552 /// \param PostViewUpdates An unordered sequence of update to perform in order
553 /// to obtain a post-view of the CFG. The DT will be updated assuming the
554 /// obtained PostViewCFG is the desired end state.
555 void applyUpdates(ArrayRef<UpdateType> Updates,
556 ArrayRef<UpdateType> PostViewUpdates) {
557 if (Updates.empty()) {
558 GraphDiff<NodePtr, IsPostDom> PostViewCFG(PostViewUpdates);
559 DomTreeBuilder::ApplyUpdates(*this, PostViewCFG, &PostViewCFG);
560 } else {
561 // PreViewCFG needs to merge Updates and PostViewCFG. The updates in
562 // Updates need to be reversed, and match the direction in PostViewCFG.
563 // The PostViewCFG is created with updates reversed (equivalent to changes
564 // made to the CFG), so the PreViewCFG needs all the updates reverse
565 // applied.
566 SmallVector<UpdateType> AllUpdates(Updates.begin(), Updates.end());
567 append_range(AllUpdates, PostViewUpdates);
568 GraphDiff<NodePtr, IsPostDom> PreViewCFG(AllUpdates,
569 /*ReverseApplyUpdates=*/true);
570 GraphDiff<NodePtr, IsPostDom> PostViewCFG(PostViewUpdates);
571 DomTreeBuilder::ApplyUpdates(*this, PreViewCFG, &PostViewCFG);
572 }
573 }
574
575 /// Inform the dominator tree about a CFG edge insertion and update the tree.
576 ///
577 /// This function has to be called just before or just after making the update
578 /// on the actual CFG. There cannot be any other updates that the dominator
579 /// tree doesn't know about.
580 ///
581 /// Note that for postdominators it automatically takes care of inserting
582 /// a reverse edge internally (so there's no need to swap the parameters).
583 ///
584 void insertEdge(NodeT *From, NodeT *To) {
585 assert(From)((void)0);
586 assert(To)((void)0);
587 assert(From->getParent() == Parent)((void)0);
588 assert(To->getParent() == Parent)((void)0);
589 DomTreeBuilder::InsertEdge(*this, From, To);
590 }
591
592 /// Inform the dominator tree about a CFG edge deletion and update the tree.
593 ///
594 /// This function has to be called just after making the update on the actual
595 /// CFG. An internal functions checks if the edge doesn't exist in the CFG in
596 /// DEBUG mode. There cannot be any other updates that the
597 /// dominator tree doesn't know about.
598 ///
599 /// Note that for postdominators it automatically takes care of deleting
600 /// a reverse edge internally (so there's no need to swap the parameters).
601 ///
602 void deleteEdge(NodeT *From, NodeT *To) {
603 assert(From)((void)0);
604 assert(To)((void)0);
605 assert(From->getParent() == Parent)((void)0);
606 assert(To->getParent() == Parent)((void)0);
607 DomTreeBuilder::DeleteEdge(*this, From, To);
608 }
609
610 /// Add a new node to the dominator tree information.
611 ///
612 /// This creates a new node as a child of DomBB dominator node, linking it
613 /// into the children list of the immediate dominator.
614 ///
615 /// \param BB New node in CFG.
616 /// \param DomBB CFG node that is dominator for BB.
617 /// \returns New dominator tree node that represents new CFG node.
618 ///
619 DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) {
620 assert(getNode(BB) == nullptr && "Block already in dominator tree!")((void)0);
621 DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB);
622 assert(IDomNode && "Not immediate dominator specified for block!")((void)0);
623 DFSInfoValid = false;
624 return createChild(BB, IDomNode);
625 }
626
627 /// Add a new node to the forward dominator tree and make it a new root.
628 ///
629 /// \param BB New node in CFG.
630 /// \returns New dominator tree node that represents new CFG node.
631 ///
632 DomTreeNodeBase<NodeT> *setNewRoot(NodeT *BB) {
633 assert(getNode(BB) == nullptr && "Block already in dominator tree!")((void)0);
634 assert(!this->isPostDominator() &&((void)0)
635 "Cannot change root of post-dominator tree")((void)0);
636 DFSInfoValid = false;
637 DomTreeNodeBase<NodeT> *NewNode = createNode(BB);
638 if (Roots.empty()) {
639 addRoot(BB);
640 } else {
641 assert(Roots.size() == 1)((void)0);
642 NodeT *OldRoot = Roots.front();
643 auto &OldNode = DomTreeNodes[OldRoot];
644 OldNode = NewNode->addChild(std::move(DomTreeNodes[OldRoot]));
645 OldNode->IDom = NewNode;
646 OldNode->UpdateLevel();
647 Roots[0] = BB;
648 }
649 return RootNode = NewNode;
650 }
651
652 /// changeImmediateDominator - This method is used to update the dominator
653 /// tree information when a node's immediate dominator changes.
654 ///
655 void changeImmediateDominator(DomTreeNodeBase<NodeT> *N,
656 DomTreeNodeBase<NodeT> *NewIDom) {
657 assert(N && NewIDom && "Cannot change null node pointers!")((void)0);
658 DFSInfoValid = false;
659 N->setIDom(NewIDom);
660 }
661
662 void changeImmediateDominator(NodeT *BB, NodeT *NewBB) {
663 changeImmediateDominator(getNode(BB), getNode(NewBB));
664 }
665
666 /// eraseNode - Removes a node from the dominator tree. Block must not
667 /// dominate any other blocks. Removes node from its immediate dominator's
668 /// children list. Deletes dominator node associated with basic block BB.
669 void eraseNode(NodeT *BB) {
670 DomTreeNodeBase<NodeT> *Node = getNode(BB);
671 assert(Node && "Removing node that isn't in dominator tree.")((void)0);
672 assert(Node->isLeaf() && "Node is not a leaf node.")((void)0);
673
674 DFSInfoValid = false;
675
676 // Remove node from immediate dominator's children list.
677 DomTreeNodeBase<NodeT> *IDom = Node->getIDom();
678 if (IDom) {
679 const auto I = find(IDom->Children, Node);
680 assert(I != IDom->Children.end() &&((void)0)
681 "Not in immediate dominator children set!")((void)0);
682 // I am no longer your child...
683 IDom->Children.erase(I);
684 }
685
686 DomTreeNodes.erase(BB);
687
688 if (!IsPostDom) return;
689
690 // Remember to update PostDominatorTree roots.
691 auto RIt = llvm::find(Roots, BB);
692 if (RIt != Roots.end()) {
693 std::swap(*RIt, Roots.back());
694 Roots.pop_back();
695 }
696 }
697
698 /// splitBlock - BB is split and now it has one successor. Update dominator
699 /// tree to reflect this change.
700 void splitBlock(NodeT *NewBB) {
701 if (IsPostDominator)
702 Split<Inverse<NodeT *>>(NewBB);
703 else
704 Split<NodeT *>(NewBB);
705 }
706
707 /// print - Convert to human readable form
708 ///
709 void print(raw_ostream &O) const {
710 O << "=============================--------------------------------\n";
711 if (IsPostDominator)
712 O << "Inorder PostDominator Tree: ";
713 else
714 O << "Inorder Dominator Tree: ";
715 if (!DFSInfoValid)
716 O << "DFSNumbers invalid: " << SlowQueries << " slow queries.";
717 O << "\n";
718
719 // The postdom tree can have a null root if there are no returns.
720 if (getRootNode()) PrintDomTree<NodeT>(getRootNode(), O, 1);
721 O << "Roots: ";
722 for (const NodePtr Block : Roots) {
723 Block->printAsOperand(O, false);
724 O << " ";
725 }
726 O << "\n";
727 }
728
729public:
730 /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking
731 /// dominator tree in dfs order.
732 void updateDFSNumbers() const {
733 if (DFSInfoValid) {
734 SlowQueries = 0;
735 return;
736 }
737
738 SmallVector<std::pair<const DomTreeNodeBase<NodeT> *,
739 typename DomTreeNodeBase<NodeT>::const_iterator>,
740 32> WorkStack;
741
742 const DomTreeNodeBase<NodeT> *ThisRoot = getRootNode();
743 assert((!Parent || ThisRoot) && "Empty constructed DomTree")((void)0);
744 if (!ThisRoot)
745 return;
746
747 // Both dominators and postdominators have a single root node. In the case
748 // case of PostDominatorTree, this node is a virtual root.
749 WorkStack.push_back({ThisRoot, ThisRoot->begin()});
750
751 unsigned DFSNum = 0;
752 ThisRoot->DFSNumIn = DFSNum++;
753
754 while (!WorkStack.empty()) {
755 const DomTreeNodeBase<NodeT> *Node = WorkStack.back().first;
756 const auto ChildIt = WorkStack.back().second;
757
758 // If we visited all of the children of this node, "recurse" back up the
759 // stack setting the DFOutNum.
760 if (ChildIt == Node->end()) {
761 Node->DFSNumOut = DFSNum++;
762 WorkStack.pop_back();
763 } else {
764 // Otherwise, recursively visit this child.
765 const DomTreeNodeBase<NodeT> *Child = *ChildIt;
766 ++WorkStack.back().second;
767
768 WorkStack.push_back({Child, Child->begin()});
769 Child->DFSNumIn = DFSNum++;
770 }
771 }
772
773 SlowQueries = 0;
774 DFSInfoValid = true;
775 }
776
777 /// recalculate - compute a dominator tree for the given function
778 void recalculate(ParentType &Func) {
779 Parent = &Func;
780 DomTreeBuilder::Calculate(*this);
781 }
782
783 void recalculate(ParentType &Func, ArrayRef<UpdateType> Updates) {
784 Parent = &Func;
785 DomTreeBuilder::CalculateWithUpdates(*this, Updates);
786 }
787
788 /// verify - checks if the tree is correct. There are 3 level of verification:
789 /// - Full -- verifies if the tree is correct by making sure all the
790 /// properties (including the parent and the sibling property)
791 /// hold.
792 /// Takes O(N^3) time.
793 ///
794 /// - Basic -- checks if the tree is correct, but compares it to a freshly
795 /// constructed tree instead of checking the sibling property.
796 /// Takes O(N^2) time.
797 ///
798 /// - Fast -- checks basic tree structure and compares it with a freshly
799 /// constructed tree.
800 /// Takes O(N^2) time worst case, but is faster in practise (same
801 /// as tree construction).
802 bool verify(VerificationLevel VL = VerificationLevel::Full) const {
803 return DomTreeBuilder::Verify(*this, VL);
804 }
805
806 void reset() {
807 DomTreeNodes.clear();
808 Roots.clear();
809 RootNode = nullptr;
810 Parent = nullptr;
811 DFSInfoValid = false;
812 SlowQueries = 0;
813 }
814
815protected:
816 void addRoot(NodeT *BB) { this->Roots.push_back(BB); }
817
818 DomTreeNodeBase<NodeT> *createChild(NodeT *BB, DomTreeNodeBase<NodeT> *IDom) {
819 return (DomTreeNodes[BB] = IDom->addChild(
820 std::make_unique<DomTreeNodeBase<NodeT>>(BB, IDom)))
821 .get();
822 }
823
824 DomTreeNodeBase<NodeT> *createNode(NodeT *BB) {
825 return (DomTreeNodes[BB] =
826 std::make_unique<DomTreeNodeBase<NodeT>>(BB, nullptr))
827 .get();
828 }
829
830 // NewBB is split and now it has one successor. Update dominator tree to
831 // reflect this change.
832 template <class N>
833 void Split(typename GraphTraits<N>::NodeRef NewBB) {
834 using GraphT = GraphTraits<N>;
835 using NodeRef = typename GraphT::NodeRef;
836 assert(std::distance(GraphT::child_begin(NewBB),((void)0)
837 GraphT::child_end(NewBB)) == 1 &&((void)0)
838 "NewBB should have a single successor!")((void)0);
839 NodeRef NewBBSucc = *GraphT::child_begin(NewBB);
840
841 SmallVector<NodeRef, 4> PredBlocks(children<Inverse<N>>(NewBB));
842
843 assert(!PredBlocks.empty() && "No predblocks?")((void)0);
844
845 bool NewBBDominatesNewBBSucc = true;
846 for (auto Pred : children<Inverse<N>>(NewBBSucc)) {
847 if (Pred != NewBB && !dominates(NewBBSucc, Pred) &&
848 isReachableFromEntry(Pred)) {
849 NewBBDominatesNewBBSucc = false;
850 break;
851 }
852 }
853
854 // Find NewBB's immediate dominator and create new dominator tree node for
855 // NewBB.
856 NodeT *NewBBIDom = nullptr;
857 unsigned i = 0;
858 for (i = 0; i < PredBlocks.size(); ++i)
859 if (isReachableFromEntry(PredBlocks[i])) {
860 NewBBIDom = PredBlocks[i];
861 break;
862 }
863
864 // It's possible that none of the predecessors of NewBB are reachable;
865 // in that case, NewBB itself is unreachable, so nothing needs to be
866 // changed.
867 if (!NewBBIDom) return;
868
869 for (i = i + 1; i < PredBlocks.size(); ++i) {
870 if (isReachableFromEntry(PredBlocks[i]))
871 NewBBIDom = findNearestCommonDominator(NewBBIDom, PredBlocks[i]);
872 }
873
874 // Create the new dominator tree node... and set the idom of NewBB.
875 DomTreeNodeBase<NodeT> *NewBBNode = addNewBlock(NewBB, NewBBIDom);
876
877 // If NewBB strictly dominates other blocks, then it is now the immediate
878 // dominator of NewBBSucc. Update the dominator tree as appropriate.
879 if (NewBBDominatesNewBBSucc) {
880 DomTreeNodeBase<NodeT> *NewBBSuccNode = getNode(NewBBSucc);
881 changeImmediateDominator(NewBBSuccNode, NewBBNode);
882 }
883 }
884
885 private:
886 bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A,
887 const DomTreeNodeBase<NodeT> *B) const {
888 assert(A != B)((void)0);
889 assert(isReachableFromEntry(B))((void)0);
890 assert(isReachableFromEntry(A))((void)0);
891
892 const unsigned ALevel = A->getLevel();
893 const DomTreeNodeBase<NodeT> *IDom;
894
895 // Don't walk nodes above A's subtree. When we reach A's level, we must
896 // either find A or be in some other subtree not dominated by A.
897 while ((IDom = B->getIDom()) != nullptr && IDom->getLevel() >= ALevel)
898 B = IDom; // Walk up the tree
899
900 return B == A;
901 }
902
903 /// Wipe this tree's state without releasing any resources.
904 ///
905 /// This is essentially a post-move helper only. It leaves the object in an
906 /// assignable and destroyable state, but otherwise invalid.
907 void wipe() {
908 DomTreeNodes.clear();
909 RootNode = nullptr;
910 Parent = nullptr;
911 }
912};
913
914template <typename T>
915using DomTreeBase = DominatorTreeBase<T, false>;
916
917template <typename T>
918using PostDomTreeBase = DominatorTreeBase<T, true>;
919
920// These two functions are declared out of line as a workaround for building
921// with old (< r147295) versions of clang because of pr11642.
922template <typename NodeT, bool IsPostDom>
923bool DominatorTreeBase<NodeT, IsPostDom>::dominates(const NodeT *A,
924 const NodeT *B) const {
925 if (A == B)
926 return true;
927
928 // Cast away the const qualifiers here. This is ok since
929 // this function doesn't actually return the values returned
930 // from getNode.
931 return dominates(getNode(const_cast<NodeT *>(A)),
932 getNode(const_cast<NodeT *>(B)));
933}
934template <typename NodeT, bool IsPostDom>
935bool DominatorTreeBase<NodeT, IsPostDom>::properlyDominates(
936 const NodeT *A, const NodeT *B) const {
937 if (A == B)
938 return false;
939
940 // Cast away the const qualifiers here. This is ok since
941 // this function doesn't actually return the values returned
942 // from getNode.
943 return dominates(getNode(const_cast<NodeT *>(A)),
944 getNode(const_cast<NodeT *>(B)));
945}
946
947} // end namespace llvm
948
949#endif // LLVM_SUPPORT_GENERICDOMTREE_H

/usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ADT/DenseMap.h

1//===- llvm/ADT/DenseMap.h - Dense probed hash table ------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines the DenseMap class.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_ADT_DENSEMAP_H
14#define LLVM_ADT_DENSEMAP_H
15
16#include "llvm/ADT/DenseMapInfo.h"
17#include "llvm/ADT/EpochTracker.h"
18#include "llvm/Support/AlignOf.h"
19#include "llvm/Support/Compiler.h"
20#include "llvm/Support/MathExtras.h"
21#include "llvm/Support/MemAlloc.h"
22#include "llvm/Support/ReverseIteration.h"
23#include "llvm/Support/type_traits.h"
24#include <algorithm>
25#include <cassert>
26#include <cstddef>
27#include <cstring>
28#include <initializer_list>
29#include <iterator>
30#include <new>
31#include <type_traits>
32#include <utility>
33
34namespace llvm {
35
36namespace detail {
37
38// We extend a pair to allow users to override the bucket type with their own
39// implementation without requiring two members.
40template <typename KeyT, typename ValueT>
41struct DenseMapPair : public std::pair<KeyT, ValueT> {
42 using std::pair<KeyT, ValueT>::pair;
43
44 KeyT &getFirst() { return std::pair<KeyT, ValueT>::first; }
45 const KeyT &getFirst() const { return std::pair<KeyT, ValueT>::first; }
46 ValueT &getSecond() { return std::pair<KeyT, ValueT>::second; }
47 const ValueT &getSecond() const { return std::pair<KeyT, ValueT>::second; }
48};
49
50} // end namespace detail
51
52template <typename KeyT, typename ValueT,
53 typename KeyInfoT = DenseMapInfo<KeyT>,
54 typename Bucket = llvm::detail::DenseMapPair<KeyT, ValueT>,
55 bool IsConst = false>
56class DenseMapIterator;
57
58template <typename DerivedT, typename KeyT, typename ValueT, typename KeyInfoT,
59 typename BucketT>
60class DenseMapBase : public DebugEpochBase {
61 template <typename T>
62 using const_arg_type_t = typename const_pointer_or_const_ref<T>::type;
63
64public:
65 using size_type = unsigned;
66 using key_type = KeyT;
67 using mapped_type = ValueT;
68 using value_type = BucketT;
69
70 using iterator = DenseMapIterator<KeyT, ValueT, KeyInfoT, BucketT>;
71 using const_iterator =
72 DenseMapIterator<KeyT, ValueT, KeyInfoT, BucketT, true>;
73
74 inline iterator begin() {
75 // When the map is empty, avoid the overhead of advancing/retreating past
76 // empty buckets.
77 if (empty())
78 return end();
79 if (shouldReverseIterate<KeyT>())
80 return makeIterator(getBucketsEnd() - 1, getBuckets(), *this);
81 return makeIterator(getBuckets(), getBucketsEnd(), *this);
82 }
83 inline iterator end() {
84 return makeIterator(getBucketsEnd(), getBucketsEnd(), *this, true);
85 }
86 inline const_iterator begin() const {
87 if (empty())
88 return end();
89 if (shouldReverseIterate<KeyT>())
90 return makeConstIterator(getBucketsEnd() - 1, getBuckets(), *this);
91 return makeConstIterator(getBuckets(), getBucketsEnd(), *this);
92 }
93 inline const_iterator end() const {
94 return makeConstIterator(getBucketsEnd(), getBucketsEnd(), *this, true);
95 }
96
97 LLVM_NODISCARD[[clang::warn_unused_result]] bool empty() const {
98 return getNumEntries() == 0;
99 }
100 unsigned size() const { return getNumEntries(); }
101
102 /// Grow the densemap so that it can contain at least \p NumEntries items
103 /// before resizing again.
104 void reserve(size_type NumEntries) {
105 auto NumBuckets = getMinBucketToReserveForEntries(NumEntries);
106 incrementEpoch();
107 if (NumBuckets > getNumBuckets())
108 grow(NumBuckets);
109 }
110
111 void clear() {
112 incrementEpoch();
113 if (getNumEntries() == 0 && getNumTombstones() == 0) return;
114
115 // If the capacity of the array is huge, and the # elements used is small,
116 // shrink the array.
117 if (getNumEntries() * 4 < getNumBuckets() && getNumBuckets() > 64) {
118 shrink_and_clear();
119 return;
120 }
121
122 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
123 if (std::is_trivially_destructible<ValueT>::value) {
124 // Use a simpler loop when values don't need destruction.
125 for (BucketT *P = getBuckets(), *E = getBucketsEnd(); P != E; ++P)
126 P->getFirst() = EmptyKey;
127 } else {
128 unsigned NumEntries = getNumEntries();
129 for (BucketT *P = getBuckets(), *E = getBucketsEnd(); P != E; ++P) {
130 if (!KeyInfoT::isEqual(P->getFirst(), EmptyKey)) {
131 if (!KeyInfoT::isEqual(P->getFirst(), TombstoneKey)) {
132 P->getSecond().~ValueT();
133 --NumEntries;
134 }
135 P->getFirst() = EmptyKey;
136 }
137 }
138 assert(NumEntries == 0 && "Node count imbalance!")((void)0);
139 }
140 setNumEntries(0);
141 setNumTombstones(0);
142 }
143
144 /// Return 1 if the specified key is in the map, 0 otherwise.
145 size_type count(const_arg_type_t<KeyT> Val) const {
146 const BucketT *TheBucket;
147 return LookupBucketFor(Val, TheBucket) ? 1 : 0;
148 }
149
150 iterator find(const_arg_type_t<KeyT> Val) {
151 BucketT *TheBucket;
152 if (LookupBucketFor(Val, TheBucket))
153 return makeIterator(TheBucket,
154 shouldReverseIterate<KeyT>() ? getBuckets()
155 : getBucketsEnd(),
156 *this, true);
157 return end();
158 }
159 const_iterator find(const_arg_type_t<KeyT> Val) const {
160 const BucketT *TheBucket;
161 if (LookupBucketFor(Val, TheBucket))
162 return makeConstIterator(TheBucket,
163 shouldReverseIterate<KeyT>() ? getBuckets()
164 : getBucketsEnd(),
165 *this, true);
166 return end();
167 }
168
169 /// Alternate version of find() which allows a different, and possibly
170 /// less expensive, key type.
171 /// The DenseMapInfo is responsible for supplying methods
172 /// getHashValue(LookupKeyT) and isEqual(LookupKeyT, KeyT) for each key
173 /// type used.
174 template<class LookupKeyT>
175 iterator find_as(const LookupKeyT &Val) {
176 BucketT *TheBucket;
177 if (LookupBucketFor(Val, TheBucket))
178 return makeIterator(TheBucket,
179 shouldReverseIterate<KeyT>() ? getBuckets()
180 : getBucketsEnd(),
181 *this, true);
182 return end();
183 }
184 template<class LookupKeyT>
185 const_iterator find_as(const LookupKeyT &Val) const {
186 const BucketT *TheBucket;
187 if (LookupBucketFor(Val, TheBucket))
188 return makeConstIterator(TheBucket,
189 shouldReverseIterate<KeyT>() ? getBuckets()
190 : getBucketsEnd(),
191 *this, true);
192 return end();
193 }
194
195 /// lookup - Return the entry for the specified key, or a default
196 /// constructed value if no such entry exists.
197 ValueT lookup(const_arg_type_t<KeyT> Val) const {
198 const BucketT *TheBucket;
199 if (LookupBucketFor(Val, TheBucket))
200 return TheBucket->getSecond();
201 return ValueT();
202 }
203
204 // Inserts key,value pair into the map if the key isn't already in the map.
205 // If the key is already in the map, it returns false and doesn't update the
206 // value.
207 std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
208 return try_emplace(KV.first, KV.second);
209 }
210
211 // Inserts key,value pair into the map if the key isn't already in the map.
212 // If the key is already in the map, it returns false and doesn't update the
213 // value.
214 std::pair<iterator, bool> insert(std::pair<KeyT, ValueT> &&KV) {
215 return try_emplace(std::move(KV.first), std::move(KV.second));
216 }
217
218 // Inserts key,value pair into the map if the key isn't already in the map.
219 // The value is constructed in-place if the key is not in the map, otherwise
220 // it is not moved.
221 template <typename... Ts>
222 std::pair<iterator, bool> try_emplace(KeyT &&Key, Ts &&... Args) {
223 BucketT *TheBucket;
224 if (LookupBucketFor(Key, TheBucket))
225 return std::make_pair(makeIterator(TheBucket,
226 shouldReverseIterate<KeyT>()
227 ? getBuckets()
228 : getBucketsEnd(),
229 *this, true),
230 false); // Already in map.
231
232 // Otherwise, insert the new element.
233 TheBucket =
234 InsertIntoBucket(TheBucket, std::move(Key), std::forward<Ts>(Args)...);
235 return std::make_pair(makeIterator(TheBucket,
236 shouldReverseIterate<KeyT>()
237 ? getBuckets()
238 : getBucketsEnd(),
239 *this, true),
240 true);
241 }
242
243 // Inserts key,value pair into the map if the key isn't already in the map.
244 // The value is constructed in-place if the key is not in the map, otherwise
245 // it is not moved.
246 template <typename... Ts>
247 std::pair<iterator, bool> try_emplace(const KeyT &Key, Ts &&... Args) {
248 BucketT *TheBucket;
249 if (LookupBucketFor(Key, TheBucket))
250 return std::make_pair(makeIterator(TheBucket,
251 shouldReverseIterate<KeyT>()
252 ? getBuckets()
253 : getBucketsEnd(),
254 *this, true),
255 false); // Already in map.
256
257 // Otherwise, insert the new element.
258 TheBucket = InsertIntoBucket(TheBucket, Key, std::forward<Ts>(Args)...);
259 return std::make_pair(makeIterator(TheBucket,
260 shouldReverseIterate<KeyT>()
261 ? getBuckets()
262 : getBucketsEnd(),
263 *this, true),
264 true);
265 }
266
267 /// Alternate version of insert() which allows a different, and possibly
268 /// less expensive, key type.
269 /// The DenseMapInfo is responsible for supplying methods
270 /// getHashValue(LookupKeyT) and isEqual(LookupKeyT, KeyT) for each key
271 /// type used.
272 template <typename LookupKeyT>
273 std::pair<iterator, bool> insert_as(std::pair<KeyT, ValueT> &&KV,
274 const LookupKeyT &Val) {
275 BucketT *TheBucket;
276 if (LookupBucketFor(Val, TheBucket))
277 return std::make_pair(makeIterator(TheBucket,
278 shouldReverseIterate<KeyT>()
279 ? getBuckets()
280 : getBucketsEnd(),
281 *this, true),
282 false); // Already in map.
283
284 // Otherwise, insert the new element.
285 TheBucket = InsertIntoBucketWithLookup(TheBucket, std::move(KV.first),
286 std::move(KV.second), Val);
287 return std::make_pair(makeIterator(TheBucket,
288 shouldReverseIterate<KeyT>()
289 ? getBuckets()
290 : getBucketsEnd(),
291 *this, true),
292 true);
293 }
294
295 /// insert - Range insertion of pairs.
296 template<typename InputIt>
297 void insert(InputIt I, InputIt E) {
298 for (; I != E; ++I)
299 insert(*I);
300 }
301
302 bool erase(const KeyT &Val) {
303 BucketT *TheBucket;
304 if (!LookupBucketFor(Val, TheBucket))
305 return false; // not in map.
306
307 TheBucket->getSecond().~ValueT();
308 TheBucket->getFirst() = getTombstoneKey();
309 decrementNumEntries();
310 incrementNumTombstones();
311 return true;
312 }
313 void erase(iterator I) {
314 BucketT *TheBucket = &*I;
315 TheBucket->getSecond().~ValueT();
316 TheBucket->getFirst() = getTombstoneKey();
317 decrementNumEntries();
318 incrementNumTombstones();
319 }
320
321 value_type& FindAndConstruct(const KeyT &Key) {
322 BucketT *TheBucket;
323 if (LookupBucketFor(Key, TheBucket))
324 return *TheBucket;
325
326 return *InsertIntoBucket(TheBucket, Key);
327 }
328
329 ValueT &operator[](const KeyT &Key) {
330 return FindAndConstruct(Key).second;
331 }
332
333 value_type& FindAndConstruct(KeyT &&Key) {
334 BucketT *TheBucket;
335 if (LookupBucketFor(Key, TheBucket))
336 return *TheBucket;
337
338 return *InsertIntoBucket(TheBucket, std::move(Key));
339 }
340
341 ValueT &operator[](KeyT &&Key) {
342 return FindAndConstruct(std::move(Key)).second;
343 }
344
345 /// isPointerIntoBucketsArray - Return true if the specified pointer points
346 /// somewhere into the DenseMap's array of buckets (i.e. either to a key or
347 /// value in the DenseMap).
348 bool isPointerIntoBucketsArray(const void *Ptr) const {
349 return Ptr >= getBuckets() && Ptr < getBucketsEnd();
350 }
351
352 /// getPointerIntoBucketsArray() - Return an opaque pointer into the buckets
353 /// array. In conjunction with the previous method, this can be used to
354 /// determine whether an insertion caused the DenseMap to reallocate.
355 const void *getPointerIntoBucketsArray() const { return getBuckets(); }
356
357protected:
358 DenseMapBase() = default;
359
360 void destroyAll() {
361 if (getNumBuckets() == 0) // Nothing to do.
362 return;
363
364 const KeyT EmptyKey = getEmptyKey(), TombstoneKey = getTombstoneKey();
365 for (BucketT *P = getBuckets(), *E = getBucketsEnd(); P != E; ++P) {
366 if (!KeyInfoT::isEqual(P->getFirst(), EmptyKey) &&
367 !KeyInfoT::isEqual(P->getFirst(), TombstoneKey))
368 P->getSecond().~ValueT();
369 P->getFirst().~KeyT();
370 }
371 }
372
373 void initEmpty() {
374 setNumEntries(0);
375 setNumTombstones(0);
376
377 assert((getNumBuckets() & (getNumBuckets()-1)) == 0 &&((void)0)
378 "# initial buckets must be a power of two!")((void)0);
379 const KeyT EmptyKey = getEmptyKey();
380 for (BucketT *B = getBuckets(), *E = getBucketsEnd(); B != E; ++B)
381 ::new (&B->getFirst()) KeyT(EmptyKey);
382 }
383
384 /// Returns the number of buckets to allocate to ensure that the DenseMap can
385 /// accommodate \p NumEntries without need to grow().
386 unsigned getMinBucketToReserveForEntries(unsigned NumEntries) {
387 // Ensure that "NumEntries * 4 < NumBuckets * 3"
388 if (NumEntries == 0)
389 return 0;
390 // +1 is required because of the strict equality.
391 // For example if NumEntries is 48, we need to return 401.
392 return NextPowerOf2(NumEntries * 4 / 3 + 1);
393 }
394
395 void moveFromOldBuckets(BucketT *OldBucketsBegin, BucketT *OldBucketsEnd) {
396 initEmpty();
397
398 // Insert all the old elements.
399 const KeyT EmptyKey = getEmptyKey();
400 const KeyT TombstoneKey = getTombstoneKey();
401 for (BucketT *B = OldBucketsBegin, *E = OldBucketsEnd; B != E; ++B) {
402 if (!KeyInfoT::isEqual(B->getFirst(), EmptyKey) &&
403 !KeyInfoT::isEqual(B->getFirst(), TombstoneKey)) {
404 // Insert the key/value into the new table.
405 BucketT *DestBucket;
406 bool FoundVal = LookupBucketFor(B->getFirst(), DestBucket);
407 (void)FoundVal; // silence warning.
408 assert(!FoundVal && "Key already in new map?")((void)0);
409 DestBucket->getFirst() = std::move(B->getFirst());
410 ::new (&DestBucket->getSecond()) ValueT(std::move(B->getSecond()));
411 incrementNumEntries();
412
413 // Free the value.
414 B->getSecond().~ValueT();
415 }
416 B->getFirst().~KeyT();
417 }
418 }
419
420 template <typename OtherBaseT>
421 void copyFrom(
422 const DenseMapBase<OtherBaseT, KeyT, ValueT, KeyInfoT, BucketT> &other) {
423 assert(&other != this)((void)0);
424 assert(getNumBuckets() == other.getNumBuckets())((void)0);
425
426 setNumEntries(other.getNumEntries());
427 setNumTombstones(other.getNumTombstones());
428
429 if (std::is_trivially_copyable<KeyT>::value &&
430 std::is_trivially_copyable<ValueT>::value)
431 memcpy(reinterpret_cast<void *>(getBuckets()), other.getBuckets(),
432 getNumBuckets() * sizeof(BucketT));
433 else
434 for (size_t i = 0; i < getNumBuckets(); ++i) {
435 ::new (&getBuckets()[i].getFirst())
436 KeyT(other.getBuckets()[i].getFirst());
437 if (!KeyInfoT::isEqual(getBuckets()[i].getFirst(), getEmptyKey()) &&
438 !KeyInfoT::isEqual(getBuckets()[i].getFirst(), getTombstoneKey()))
439 ::new (&getBuckets()[i].getSecond())
440 ValueT(other.getBuckets()[i].getSecond());
441 }
442 }
443
444 static unsigned getHashValue(const KeyT &Val) {
445 return KeyInfoT::getHashValue(Val);
446 }
447
448 template<typename LookupKeyT>
449 static unsigned getHashValue(const LookupKeyT &Val) {
450 return KeyInfoT::getHashValue(Val);
451 }
452
453 static const KeyT getEmptyKey() {
454 static_assert(std::is_base_of<DenseMapBase, DerivedT>::value,
455 "Must pass the derived type to this template!");
456 return KeyInfoT::getEmptyKey();
457 }
458
459 static const KeyT getTombstoneKey() {
460 return KeyInfoT::getTombstoneKey();
461 }
462
463private:
464 iterator makeIterator(BucketT *P, BucketT *E,
465 DebugEpochBase &Epoch,
466 bool NoAdvance=false) {
467 if (shouldReverseIterate<KeyT>()) {
468 BucketT *B = P == getBucketsEnd() ? getBuckets() : P + 1;
469 return iterator(B, E, Epoch, NoAdvance);
470 }
471 return iterator(P, E, Epoch, NoAdvance);
472 }
473
474 const_iterator makeConstIterator(const BucketT *P, const BucketT *E,
475 const DebugEpochBase &Epoch,
476 const bool NoAdvance=false) const {
477 if (shouldReverseIterate<KeyT>()) {
478 const BucketT *B = P == getBucketsEnd() ? getBuckets() : P + 1;
479 return const_iterator(B, E, Epoch, NoAdvance);
480 }
481 return const_iterator(P, E, Epoch, NoAdvance);
482 }
483
484 unsigned getNumEntries() const {
485 return static_cast<const DerivedT *>(this)->getNumEntries();
486 }
487
488 void setNumEntries(unsigned Num) {
489 static_cast<DerivedT *>(this)->setNumEntries(Num);
490 }
491
492 void incrementNumEntries() {
493 setNumEntries(getNumEntries() + 1);
494 }
495
496 void decrementNumEntries() {
497 setNumEntries(getNumEntries() - 1);
498 }
499
500 unsigned getNumTombstones() const {
501 return static_cast<const DerivedT *>(this)->getNumTombstones();
502 }
503
504 void setNumTombstones(unsigned Num) {
505 static_cast<DerivedT *>(this)->setNumTombstones(Num);
506 }
507
508 void incrementNumTombstones() {
509 setNumTombstones(getNumTombstones() + 1);
510 }
511
512 void decrementNumTombstones() {
513 setNumTombstones(getNumTombstones() - 1);
514 }
515
516 const BucketT *getBuckets() const {
517 return static_cast<const DerivedT *>(this)->getBuckets();
518 }
519
520 BucketT *getBuckets() {
521 return static_cast<DerivedT *>(this)->getBuckets();
522 }
523
524 unsigned getNumBuckets() const {
525 return static_cast<const DerivedT *>(this)->getNumBuckets();
526 }
527
528 BucketT *getBucketsEnd() {
529 return getBuckets() + getNumBuckets();
530 }
531
532 const BucketT *getBucketsEnd() const {
533 return getBuckets() + getNumBuckets();
534 }
535
536 void grow(unsigned AtLeast) {
537 static_cast<DerivedT *>(this)->grow(AtLeast);
538 }
539
540 void shrink_and_clear() {
541 static_cast<DerivedT *>(this)->shrink_and_clear();
542 }
543
544 template <typename KeyArg, typename... ValueArgs>
545 BucketT *InsertIntoBucket(BucketT *TheBucket, KeyArg &&Key,
546 ValueArgs &&... Values) {
547 TheBucket = InsertIntoBucketImpl(Key, Key, TheBucket);
548
549 TheBucket->getFirst() = std::forward<KeyArg>(Key);
550 ::new (&TheBucket->getSecond()) ValueT(std::forward<ValueArgs>(Values)...);
551 return TheBucket;
552 }
553
554 template <typename LookupKeyT>
555 BucketT *InsertIntoBucketWithLookup(BucketT *TheBucket, KeyT &&Key,
556 ValueT &&Value, LookupKeyT &Lookup) {
557 TheBucket = InsertIntoBucketImpl(Key, Lookup, TheBucket);
558
559 TheBucket->getFirst() = std::move(Key);
560 ::new (&TheBucket->getSecond()) ValueT(std::move(Value));
561 return TheBucket;
562 }
563
564 template <typename LookupKeyT>
565 BucketT *InsertIntoBucketImpl(const KeyT &Key, const LookupKeyT &Lookup,
566 BucketT *TheBucket) {
567 incrementEpoch();
568
569 // If the load of the hash table is more than 3/4, or if fewer than 1/8 of
570 // the buckets are empty (meaning that many are filled with tombstones),
571 // grow the table.
572 //
573 // The later case is tricky. For example, if we had one empty bucket with
574 // tons of tombstones, failing lookups (e.g. for insertion) would have to
575 // probe almost the entire table until it found the empty bucket. If the
576 // table completely filled with tombstones, no lookup would ever succeed,
577 // causing infinite loops in lookup.
578 unsigned NewNumEntries = getNumEntries() + 1;
579 unsigned NumBuckets = getNumBuckets();
580 if (LLVM_UNLIKELY(NewNumEntries * 4 >= NumBuckets * 3)__builtin_expect((bool)(NewNumEntries * 4 >= NumBuckets * 3
), false)
) {
581 this->grow(NumBuckets * 2);
582 LookupBucketFor(Lookup, TheBucket);
583 NumBuckets = getNumBuckets();
584 } else if (LLVM_UNLIKELY(NumBuckets-(NewNumEntries+getNumTombstones()) <=__builtin_expect((bool)(NumBuckets-(NewNumEntries+getNumTombstones
()) <= NumBuckets/8), false)
585 NumBuckets/8)__builtin_expect((bool)(NumBuckets-(NewNumEntries+getNumTombstones
()) <= NumBuckets/8), false)
) {
586 this->grow(NumBuckets);
587 LookupBucketFor(Lookup, TheBucket);
588 }
589 assert(TheBucket)((void)0);
590
591 // Only update the state after we've grown our bucket space appropriately
592 // so that when growing buckets we have self-consistent entry count.
593 incrementNumEntries();
594
595 // If we are writing over a tombstone, remember this.
596 const KeyT EmptyKey = getEmptyKey();
597 if (!KeyInfoT::isEqual(TheBucket->getFirst(), EmptyKey))
598 decrementNumTombstones();
599
600 return TheBucket;
601 }
602
603 /// LookupBucketFor - Lookup the appropriate bucket for Val, returning it in
604 /// FoundBucket. If the bucket contains the key and a value, this returns
605 /// true, otherwise it returns a bucket with an empty marker or tombstone and
606 /// returns false.
607 template<typename LookupKeyT>
608 bool LookupBucketFor(const LookupKeyT &Val,
609 const BucketT *&FoundBucket) const {
610 const BucketT *BucketsPtr = getBuckets();
611 const unsigned NumBuckets = getNumBuckets();
612
613 if (NumBuckets == 0) {
614 FoundBucket = nullptr;
615 return false;
616 }
617
618 // FoundTombstone - Keep track of whether we find a tombstone while probing.
619 const BucketT *FoundTombstone = nullptr;
620 const KeyT EmptyKey = getEmptyKey();
621 const KeyT TombstoneKey = getTombstoneKey();
622 assert(!KeyInfoT::isEqual(Val, EmptyKey) &&((void)0)
623 !KeyInfoT::isEqual(Val, TombstoneKey) &&((void)0)
624 "Empty/Tombstone value shouldn't be inserted into map!")((void)0);
625
626 unsigned BucketNo = getHashValue(Val) & (NumBuckets-1);
627 unsigned ProbeAmt = 1;
628 while (true) {
629 const BucketT *ThisBucket = BucketsPtr + BucketNo;
630 // Found Val's bucket? If so, return it.
631 if (LLVM_LIKELY(KeyInfoT::isEqual(Val, ThisBucket->getFirst()))__builtin_expect((bool)(KeyInfoT::isEqual(Val, ThisBucket->
getFirst())), true)
) {
632 FoundBucket = ThisBucket;
633 return true;
634 }
635
636 // If we found an empty bucket, the key doesn't exist in the set.
637 // Insert it and return the default value.
638 if (LLVM_LIKELY(KeyInfoT::isEqual(ThisBucket->getFirst(), EmptyKey))__builtin_expect((bool)(KeyInfoT::isEqual(ThisBucket->getFirst
(), EmptyKey)), true)
) {
639 // If we've already seen a tombstone while probing, fill it in instead
640 // of the empty bucket we eventually probed to.
641 FoundBucket = FoundTombstone ? FoundTombstone : ThisBucket;
642 return false;
643 }
644
645 // If this is a tombstone, remember it. If Val ends up not in the map, we
646 // prefer to return it than something that would require more probing.
647 if (KeyInfoT::isEqual(ThisBucket->getFirst(), TombstoneKey) &&
648 !FoundTombstone)
649 FoundTombstone = ThisBucket; // Remember the first tombstone found.
650
651 // Otherwise, it's a hash collision or a tombstone, continue quadratic
652 // probing.
653 BucketNo += ProbeAmt++;
654 BucketNo &= (NumBuckets-1);
655 }
656 }
657
658 template <typename LookupKeyT>
659 bool LookupBucketFor(const LookupKeyT &Val, BucketT *&FoundBucket) {
660 const BucketT *ConstFoundBucket;
661 bool Result = const_cast<const DenseMapBase *>(this)
662 ->LookupBucketFor(Val, ConstFoundBucket);
663 FoundBucket = const_cast<BucketT *>(ConstFoundBucket);
664 return Result;
665 }
666
667public:
668 /// Return the approximate size (in bytes) of the actual map.
669 /// This is just the raw memory used by DenseMap.
670 /// If entries are pointers to objects, the size of the referenced objects
671 /// are not included.
672 size_t getMemorySize() const {
673 return getNumBuckets() * sizeof(BucketT);
674 }
675};
676
677/// Equality comparison for DenseMap.
678///
679/// Iterates over elements of LHS confirming that each (key, value) pair in LHS
680/// is also in RHS, and that no additional pairs are in RHS.
681/// Equivalent to N calls to RHS.find and N value comparisons. Amortized
682/// complexity is linear, worst case is O(N^2) (if every hash collides).
683template <typename DerivedT, typename KeyT, typename ValueT, typename KeyInfoT,
684 typename BucketT>
685bool operator==(
686 const DenseMapBase<DerivedT, KeyT, ValueT, KeyInfoT, BucketT> &LHS,
687 const DenseMapBase<DerivedT, KeyT, ValueT, KeyInfoT, BucketT> &RHS) {
688 if (LHS.size() != RHS.size())
689 return false;
690
691 for (auto &KV : LHS) {
692 auto I = RHS.find(KV.first);
693 if (I == RHS.end() || I->second != KV.second)
694 return false;
695 }
696
697 return true;
698}
699
700/// Inequality comparison for DenseMap.
701///
702/// Equivalent to !(LHS == RHS). See operator== for performance notes.
703template <typename DerivedT, typename KeyT, typename ValueT, typename KeyInfoT,
704 typename BucketT>
705bool operator!=(
706 const DenseMapBase<DerivedT, KeyT, ValueT, KeyInfoT, BucketT> &LHS,
707 const DenseMapBase<DerivedT, KeyT, ValueT, KeyInfoT, BucketT> &RHS) {
708 return !(LHS == RHS);
709}
710
711template <typename KeyT, typename ValueT,
712 typename KeyInfoT = DenseMapInfo<KeyT>,
713 typename BucketT = llvm::detail::DenseMapPair<KeyT, ValueT>>
714class DenseMap : public DenseMapBase<DenseMap<KeyT, ValueT, KeyInfoT, BucketT>,
715 KeyT, ValueT, KeyInfoT, BucketT> {
716 friend class DenseMapBase<DenseMap, KeyT, ValueT, KeyInfoT, BucketT>;
717
718 // Lift some types from the dependent base class into this class for
719 // simplicity of referring to them.
720 using BaseT = DenseMapBase<DenseMap, KeyT, ValueT, KeyInfoT, BucketT>;
721
722 BucketT *Buckets;
723 unsigned NumEntries;
724 unsigned NumTombstones;
725 unsigned NumBuckets;
726
727public:
728 /// Create a DenseMap with an optional \p InitialReserve that guarantee that
729 /// this number of elements can be inserted in the map without grow()
730 explicit DenseMap(unsigned InitialReserve = 0) { init(InitialReserve); }
731
732 DenseMap(const DenseMap &other) : BaseT() {
733 init(0);
734 copyFrom(other);
735 }
736
737 DenseMap(DenseMap &&other) : BaseT() {
738 init(0);
739 swap(other);
740 }
741
742 template<typename InputIt>
743 DenseMap(const InputIt &I, const InputIt &E) {
744 init(std::distance(I, E));
745 this->insert(I, E);
746 }
747
748 DenseMap(std::initializer_list<typename BaseT::value_type> Vals) {
749 init(Vals.size());
750 this->insert(Vals.begin(), Vals.end());
751 }
752
753 ~DenseMap() {
754 this->destroyAll();
755 deallocate_buffer(Buckets, sizeof(BucketT) * NumBuckets, alignof(BucketT));
756 }
757
758 void swap(DenseMap& RHS) {
759 this->incrementEpoch();
760 RHS.incrementEpoch();
761 std::swap(Buckets, RHS.Buckets);
762 std::swap(NumEntries, RHS.NumEntries);
763 std::swap(NumTombstones, RHS.NumTombstones);
764 std::swap(NumBuckets, RHS.NumBuckets);
765 }
766
767 DenseMap& operator=(const DenseMap& other) {
768 if (&other != this)
769 copyFrom(other);
770 return *this;
771 }
772
773 DenseMap& operator=(DenseMap &&other) {
774 this->destroyAll();
775 deallocate_buffer(Buckets, sizeof(BucketT) * NumBuckets, alignof(BucketT));
776 init(0);
777 swap(other);
778 return *this;
779 }
780
781 void copyFrom(const DenseMap& other) {
782 this->destroyAll();
783 deallocate_buffer(Buckets, sizeof(BucketT) * NumBuckets, alignof(BucketT));
784 if (allocateBuckets(other.NumBuckets)) {
785 this->BaseT::copyFrom(other);
786 } else {
787 NumEntries = 0;
788 NumTombstones = 0;
789 }
790 }
791
792 void init(unsigned InitNumEntries) {
793 auto InitBuckets = BaseT::getMinBucketToReserveForEntries(InitNumEntries);
794 if (allocateBuckets(InitBuckets)) {
795 this->BaseT::initEmpty();
796 } else {
797 NumEntries = 0;
798 NumTombstones = 0;
799 }
800 }
801
802 void grow(unsigned AtLeast) {
803 unsigned OldNumBuckets = NumBuckets;
804 BucketT *OldBuckets = Buckets;
805
806 allocateBuckets(std::max<unsigned>(64, static_cast<unsigned>(NextPowerOf2(AtLeast-1))));
807 assert(Buckets)((void)0);
808 if (!OldBuckets) {
809 this->BaseT::initEmpty();
810 return;
811 }
812
813 this->moveFromOldBuckets(OldBuckets, OldBuckets+OldNumBuckets);
814
815 // Free the old table.
816 deallocate_buffer(OldBuckets, sizeof(BucketT) * OldNumBuckets,
817 alignof(BucketT));
818 }
819
820 void shrink_and_clear() {
821 unsigned OldNumBuckets = NumBuckets;
822 unsigned OldNumEntries = NumEntries;
823 this->destroyAll();
824
825 // Reduce the number of buckets.
826 unsigned NewNumBuckets = 0;
827 if (OldNumEntries)
828 NewNumBuckets = std::max(64, 1 << (Log2_32_Ceil(OldNumEntries) + 1));
829 if (NewNumBuckets == NumBuckets) {
830 this->BaseT::initEmpty();
831 return;
832 }
833
834 deallocate_buffer(Buckets, sizeof(BucketT) * OldNumBuckets,
835 alignof(BucketT));
836 init(NewNumBuckets);
837 }
838
839private:
840 unsigned getNumEntries() const {
841 return NumEntries;
842 }
843
844 void setNumEntries(unsigned Num) {
845 NumEntries = Num;
846 }
847
848 unsigned getNumTombstones() const {
849 return NumTombstones;
850 }
851
852 void setNumTombstones(unsigned Num) {
853 NumTombstones = Num;
854 }
855
856 BucketT *getBuckets() const {
857 return Buckets;
858 }
859
860 unsigned getNumBuckets() const {
861 return NumBuckets;
862 }
863
864 bool allocateBuckets(unsigned Num) {
865 NumBuckets = Num;
866 if (NumBuckets == 0) {
867 Buckets = nullptr;
868 return false;
869 }
870
871 Buckets = static_cast<BucketT *>(
872 allocate_buffer(sizeof(BucketT) * NumBuckets, alignof(BucketT)));
873 return true;
874 }
875};
876
877template <typename KeyT, typename ValueT, unsigned InlineBuckets = 4,
878 typename KeyInfoT = DenseMapInfo<KeyT>,
879 typename BucketT = llvm::detail::DenseMapPair<KeyT, ValueT>>
880class SmallDenseMap
881 : public DenseMapBase<
882 SmallDenseMap<KeyT, ValueT, InlineBuckets, KeyInfoT, BucketT>, KeyT,
883 ValueT, KeyInfoT, BucketT> {
884 friend class DenseMapBase<SmallDenseMap, KeyT, ValueT, KeyInfoT, BucketT>;
885
886 // Lift some types from the dependent base class into this class for
887 // simplicity of referring to them.
888 using BaseT = DenseMapBase<SmallDenseMap, KeyT, ValueT, KeyInfoT, BucketT>;
889
890 static_assert(isPowerOf2_64(InlineBuckets),
891 "InlineBuckets must be a power of 2.");
892
893 unsigned Small : 1;
894 unsigned NumEntries : 31;
895 unsigned NumTombstones;
896
897 struct LargeRep {
898 BucketT *Buckets;
899 unsigned NumBuckets;
900 };
901
902 /// A "union" of an inline bucket array and the struct representing
903 /// a large bucket. This union will be discriminated by the 'Small' bit.
904 AlignedCharArrayUnion<BucketT[InlineBuckets], LargeRep> storage;
905
906public:
907 explicit SmallDenseMap(unsigned NumInitBuckets = 0) {
908 init(NumInitBuckets);
909 }
910
911 SmallDenseMap(const SmallDenseMap &other) : BaseT() {
912 init(0);
913 copyFrom(other);
914 }
915
916 SmallDenseMap(SmallDenseMap &&other) : BaseT() {
917 init(0);
918 swap(other);
919 }
920
921 template<typename InputIt>
922 SmallDenseMap(const InputIt &I, const InputIt &E) {
923 init(NextPowerOf2(std::distance(I, E)));
924 this->insert(I, E);
925 }
926
927 SmallDenseMap(std::initializer_list<typename BaseT::value_type> Vals)
928 : SmallDenseMap(Vals.begin(), Vals.end()) {}
929
930 ~SmallDenseMap() {
931 this->destroyAll();
932 deallocateBuckets();
933 }
934
935 void swap(SmallDenseMap& RHS) {
936 unsigned TmpNumEntries = RHS.NumEntries;
937 RHS.NumEntries = NumEntries;
938 NumEntries = TmpNumEntries;
939 std::swap(NumTombstones, RHS.NumTombstones);
940
941 const KeyT EmptyKey = this->getEmptyKey();
942 const KeyT TombstoneKey = this->getTombstoneKey();
943 if (Small && RHS.Small) {
944 // If we're swapping inline bucket arrays, we have to cope with some of
945 // the tricky bits of DenseMap's storage system: the buckets are not
946 // fully initialized. Thus we swap every key, but we may have
947 // a one-directional move of the value.
948 for (unsigned i = 0, e = InlineBuckets; i != e; ++i) {
949 BucketT *LHSB = &getInlineBuckets()[i],
950 *RHSB = &RHS.getInlineBuckets()[i];
951 bool hasLHSValue = (!KeyInfoT::isEqual(LHSB->getFirst(), EmptyKey) &&
952 !KeyInfoT::isEqual(LHSB->getFirst(), TombstoneKey));
953 bool hasRHSValue = (!KeyInfoT::isEqual(RHSB->getFirst(), EmptyKey) &&
954 !KeyInfoT::isEqual(RHSB->getFirst(), TombstoneKey));
955 if (hasLHSValue && hasRHSValue) {
956 // Swap together if we can...
957 std::swap(*LHSB, *RHSB);
958 continue;
959 }
960 // Swap separately and handle any asymmetry.
961 std::swap(LHSB->getFirst(), RHSB->getFirst());
962 if (hasLHSValue) {
963 ::new (&RHSB->getSecond()) ValueT(std::move(LHSB->getSecond()));
964 LHSB->getSecond().~ValueT();
965 } else if (hasRHSValue) {
966 ::new (&LHSB->getSecond()) ValueT(std::move(RHSB->getSecond()));
967 RHSB->getSecond().~ValueT();
968 }
969 }
970 return;
971 }
972 if (!Small && !RHS.Small) {
973 std::swap(getLargeRep()->Buckets, RHS.getLargeRep()->Buckets);
974 std::swap(getLargeRep()->NumBuckets, RHS.getLargeRep()->NumBuckets);
975 return;
976 }
977
978 SmallDenseMap &SmallSide = Small ? *this : RHS;
979 SmallDenseMap &LargeSide = Small ? RHS : *this;
980
981 // First stash the large side's rep and move the small side across.
982 LargeRep TmpRep = std::move(*LargeSide.getLargeRep());
983 LargeSide.getLargeRep()->~LargeRep();
984 LargeSide.Small = true;
985 // This is similar to the standard move-from-old-buckets, but the bucket
986 // count hasn't actually rotated in this case. So we have to carefully
987 // move construct the keys and values into their new locations, but there
988 // is no need to re-hash things.
989 for (unsigned i = 0, e = InlineBuckets; i != e; ++i) {
990 BucketT *NewB = &LargeSide.getInlineBuckets()[i],
991 *OldB = &SmallSide.getInlineBuckets()[i];
992 ::new (&NewB->getFirst()) KeyT(std::move(OldB->getFirst()));
993 OldB->getFirst().~KeyT();
994 if (!KeyInfoT::isEqual(NewB->getFirst(), EmptyKey) &&
995 !KeyInfoT::isEqual(NewB->getFirst(), TombstoneKey)) {
996 ::new (&NewB->getSecond()) ValueT(std::move(OldB->getSecond()));
997 OldB->getSecond().~ValueT();
998 }
999 }
1000
1001 // The hard part of moving the small buckets across is done, just move
1002 // the TmpRep into its new home.
1003 SmallSide.Small = false;
1004 new (SmallSide.getLargeRep()) LargeRep(std::move(TmpRep));
1005 }
1006
1007 SmallDenseMap& operator=(const SmallDenseMap& other) {
1008 if (&other != this)
1009 copyFrom(other);
1010 return *this;
1011 }
1012
1013 SmallDenseMap& operator=(SmallDenseMap &&other) {
1014 this->destroyAll();
1015 deallocateBuckets();
1016 init(0);
1017 swap(other);
1018 return *this;
1019 }
1020
1021 void copyFrom(const SmallDenseMap& other) {
1022 this->destroyAll();
1023 deallocateBuckets();
1024 Small = true;
1025 if (other.getNumBuckets() > InlineBuckets) {
1026 Small = false;
1027 new (getLargeRep()) LargeRep(allocateBuckets(other.getNumBuckets()));
1028 }
1029 this->BaseT::copyFrom(other);
1030 }
1031
1032 void init(unsigned InitBuckets) {
1033 Small = true;
1034 if (InitBuckets > InlineBuckets) {
1035 Small = false;
1036 new (getLargeRep()) LargeRep(allocateBuckets(InitBuckets));
1037 }
1038 this->BaseT::initEmpty();
1039 }
1040
1041 void grow(unsigned AtLeast) {
1042 if (AtLeast > InlineBuckets)
1043 AtLeast = std::max<unsigned>(64, NextPowerOf2(AtLeast-1));
1044
1045 if (Small) {
1046 // First move the inline buckets into a temporary storage.
1047 AlignedCharArrayUnion<BucketT[InlineBuckets]> TmpStorage;
1048 BucketT *TmpBegin = reinterpret_cast<BucketT *>(&TmpStorage);
1049 BucketT *TmpEnd = TmpBegin;
1050
1051 // Loop over the buckets, moving non-empty, non-tombstones into the
1052 // temporary storage. Have the loop move the TmpEnd forward as it goes.
1053 const KeyT EmptyKey = this->getEmptyKey();
1054 const KeyT TombstoneKey = this->getTombstoneKey();
1055 for (BucketT *P = getBuckets(), *E = P + InlineBuckets; P != E; ++P) {
1056 if (!KeyInfoT::isEqual(P->getFirst(), EmptyKey) &&
1057 !KeyInfoT::isEqual(P->getFirst(), TombstoneKey)) {
1058 assert(size_t(TmpEnd - TmpBegin) < InlineBuckets &&((void)0)
1059 "Too many inline buckets!")((void)0);
1060 ::new (&TmpEnd->getFirst()) KeyT(std::move(P->getFirst()));
1061 ::new (&TmpEnd->getSecond()) ValueT(std::move(P->getSecond()));
1062 ++TmpEnd;
1063 P->getSecond().~ValueT();
1064 }
1065 P->getFirst().~KeyT();
1066 }
1067
1068 // AtLeast == InlineBuckets can happen if there are many tombstones,
1069 // and grow() is used to remove them. Usually we always switch to the
1070 // large rep here.
1071 if (AtLeast > InlineBuckets) {
1072 Small = false;
1073 new (getLargeRep()) LargeRep(allocateBuckets(AtLeast));
1074 }
1075 this->moveFromOldBuckets(TmpBegin, TmpEnd);
1076 return;
1077 }
1078
1079 LargeRep OldRep = std::move(*getLargeRep());
1080 getLargeRep()->~LargeRep();
1081 if (AtLeast <= InlineBuckets) {
1082 Small = true;
1083 } else {
1084 new (getLargeRep()) LargeRep(allocateBuckets(AtLeast));
1085 }
1086
1087 this->moveFromOldBuckets(OldRep.Buckets, OldRep.Buckets+OldRep.NumBuckets);
1088
1089 // Free the old table.
1090 deallocate_buffer(OldRep.Buckets, sizeof(BucketT) * OldRep.NumBuckets,
1091 alignof(BucketT));
1092 }
1093
1094 void shrink_and_clear() {
1095 unsigned OldSize = this->size();
1096 this->destroyAll();
1097
1098 // Reduce the number of buckets.
1099 unsigned NewNumBuckets = 0;
1100 if (OldSize) {
1101 NewNumBuckets = 1 << (Log2_32_Ceil(OldSize) + 1);
1102 if (NewNumBuckets > InlineBuckets && NewNumBuckets < 64u)
1103 NewNumBuckets = 64;
1104 }
1105 if ((Small && NewNumBuckets <= InlineBuckets) ||
1106 (!Small && NewNumBuckets == getLargeRep()->NumBuckets)) {
1107 this->BaseT::initEmpty();
1108 return;
1109 }
1110
1111 deallocateBuckets();
1112 init(NewNumBuckets);
1113 }
1114
1115private:
1116 unsigned getNumEntries() const {
1117 return NumEntries;
1118 }
1119
1120 void setNumEntries(unsigned Num) {
1121 // NumEntries is hardcoded to be 31 bits wide.
1122 assert(Num < (1U << 31) && "Cannot support more than 1<<31 entries")((void)0);
1123 NumEntries = Num;
1124 }
1125
1126 unsigned getNumTombstones() const {
1127 return NumTombstones;
1128 }
1129
1130 void setNumTombstones(unsigned Num) {
1131 NumTombstones = Num;
1132 }
1133
1134 const BucketT *getInlineBuckets() const {
1135 assert(Small)((void)0);
1136 // Note that this cast does not violate aliasing rules as we assert that
1137 // the memory's dynamic type is the small, inline bucket buffer, and the
1138 // 'storage' is a POD containing a char buffer.
1139 return reinterpret_cast<const BucketT *>(&storage);
1140 }
1141
1142 BucketT *getInlineBuckets() {
1143 return const_cast<BucketT *>(
1144 const_cast<const SmallDenseMap *>(this)->getInlineBuckets());
1145 }
1146
1147 const LargeRep *getLargeRep() const {
1148 assert(!Small)((void)0);
1149 // Note, same rule about aliasing as with getInlineBuckets.
1150 return reinterpret_cast<const LargeRep *>(&storage);
1151 }
1152
1153 LargeRep *getLargeRep() {
1154 return const_cast<LargeRep *>(
1155 const_cast<const SmallDenseMap *>(this)->getLargeRep());
1156 }
1157
1158 const BucketT *getBuckets() const {
1159 return Small ? getInlineBuckets() : getLargeRep()->Buckets;
1160 }
1161
1162 BucketT *getBuckets() {
1163 return const_cast<BucketT *>(
1164 const_cast<const SmallDenseMap *>(this)->getBuckets());
1165 }
1166
1167 unsigned getNumBuckets() const {
1168 return Small ? InlineBuckets : getLargeRep()->NumBuckets;
1169 }
1170
1171 void deallocateBuckets() {
1172 if (Small)
1173 return;
1174
1175 deallocate_buffer(getLargeRep()->Buckets,
1176 sizeof(BucketT) * getLargeRep()->NumBuckets,
1177 alignof(BucketT));
1178 getLargeRep()->~LargeRep();
1179 }
1180
1181 LargeRep allocateBuckets(unsigned Num) {
1182 assert(Num > InlineBuckets && "Must allocate more buckets than are inline")((void)0);
1183 LargeRep Rep = {static_cast<BucketT *>(allocate_buffer(
1184 sizeof(BucketT) * Num, alignof(BucketT))),
1185 Num};
1186 return Rep;
1187 }
1188};
1189
1190template <typename KeyT, typename ValueT, typename KeyInfoT, typename Bucket,
1191 bool IsConst>
1192class DenseMapIterator : DebugEpochBase::HandleBase {
1193 friend class DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, true>;
1194 friend class DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, false>;
1195
1196public:
1197 using difference_type = ptrdiff_t;
1198 using value_type =
1199 typename std::conditional<IsConst, const Bucket, Bucket>::type;
1200 using pointer = value_type *;
1201 using reference = value_type &;
1202 using iterator_category = std::forward_iterator_tag;
1203
1204private:
1205 pointer Ptr = nullptr;
1206 pointer End = nullptr;
1207
1208public:
1209 DenseMapIterator() = default;
1210
1211 DenseMapIterator(pointer Pos, pointer E, const DebugEpochBase &Epoch,
1212 bool NoAdvance = false)
1213 : DebugEpochBase::HandleBase(&Epoch), Ptr(Pos), End(E) {
1214 assert(isHandleInSync() && "invalid construction!")((void)0);
1215
1216 if (NoAdvance) return;
1217 if (shouldReverseIterate<KeyT>()) {
1218 RetreatPastEmptyBuckets();
1219 return;
1220 }
1221 AdvancePastEmptyBuckets();
1222 }
1223
1224 // Converting ctor from non-const iterators to const iterators. SFINAE'd out
1225 // for const iterator destinations so it doesn't end up as a user defined copy
1226 // constructor.
1227 template <bool IsConstSrc,
1228 typename = std::enable_if_t<!IsConstSrc && IsConst>>
1229 DenseMapIterator(
1230 const DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, IsConstSrc> &I)
1231 : DebugEpochBase::HandleBase(I), Ptr(I.Ptr), End(I.End) {}
1232
1233 reference operator*() const {
1234 assert(isHandleInSync() && "invalid iterator access!")((void)0);
1235 assert(Ptr != End && "dereferencing end() iterator")((void)0);
1236 if (shouldReverseIterate<KeyT>())
1237 return Ptr[-1];
1238 return *Ptr;
1239 }
1240 pointer operator->() const {
1241 assert(isHandleInSync() && "invalid iterator access!")((void)0);
1242 assert(Ptr != End && "dereferencing end() iterator")((void)0);
1243 if (shouldReverseIterate<KeyT>())
1244 return &(Ptr[-1]);
1245 return Ptr;
1246 }
1247
1248 friend bool operator==(const DenseMapIterator &LHS,
1249 const DenseMapIterator &RHS) {
1250 assert((!LHS.Ptr || LHS.isHandleInSync()) && "handle not in sync!")((void)0);
1251 assert((!RHS.Ptr || RHS.isHandleInSync()) && "handle not in sync!")((void)0);
1252 assert(LHS.getEpochAddress() == RHS.getEpochAddress() &&((void)0)
1253 "comparing incomparable iterators!")((void)0);
1254 return LHS.Ptr == RHS.Ptr;
44
Assuming 'LHS.Ptr' is not equal to 'RHS.Ptr'
45
Returning zero, which participates in a condition later
1255 }
1256
1257 friend bool operator!=(const DenseMapIterator &LHS,
1258 const DenseMapIterator &RHS) {
1259 return !(LHS == RHS);
43
Calling 'operator=='
46
Returning from 'operator=='
47
Returning the value 1, which participates in a condition later
1260 }
1261
1262 inline DenseMapIterator& operator++() { // Preincrement
1263 assert(isHandleInSync() && "invalid iterator access!")((void)0);
1264 assert(Ptr != End && "incrementing end() iterator")((void)0);
1265 if (shouldReverseIterate<KeyT>()) {
1266 --Ptr;
1267 RetreatPastEmptyBuckets();
1268 return *this;
1269 }
1270 ++Ptr;
1271 AdvancePastEmptyBuckets();
1272 return *this;
1273 }
1274 DenseMapIterator operator++(int) { // Postincrement
1275 assert(isHandleInSync() && "invalid iterator access!")((void)0);
1276 DenseMapIterator tmp = *this; ++*this; return tmp;
1277 }
1278
1279private:
1280 void AdvancePastEmptyBuckets() {
1281 assert(Ptr <= End)((void)0);
1282 const KeyT Empty = KeyInfoT::getEmptyKey();
1283 const KeyT Tombstone = KeyInfoT::getTombstoneKey();
1284
1285 while (Ptr != End && (KeyInfoT::isEqual(Ptr->getFirst(), Empty) ||
1286 KeyInfoT::isEqual(Ptr->getFirst(), Tombstone)))
1287 ++Ptr;
1288 }
1289
1290 void RetreatPastEmptyBuckets() {
1291 assert(Ptr >= End)((void)0);
1292 const KeyT Empty = KeyInfoT::getEmptyKey();
1293 const KeyT Tombstone = KeyInfoT::getTombstoneKey();
1294
1295 while (Ptr != End && (KeyInfoT::isEqual(Ptr[-1].getFirst(), Empty) ||
1296 KeyInfoT::isEqual(Ptr[-1].getFirst(), Tombstone)))
1297 --Ptr;
1298 }
1299};
1300
1301template <typename KeyT, typename ValueT, typename KeyInfoT>
1302inline size_t capacity_in_bytes(const DenseMap<KeyT, ValueT, KeyInfoT> &X) {
1303 return X.getMemorySize();
1304}
1305
1306} // end namespace llvm
1307
1308#endif // LLVM_ADT_DENSEMAP_H