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 LoopSimplify.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 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/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/Transforms/Utils/LoopSimplify.cpp

/usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Transforms/Utils/LoopSimplify.cpp

1//===- LoopSimplify.cpp - Loop Canonicalization Pass ----------------------===//
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 performs several transformations to transform natural loops into a
10// simpler form, which makes subsequent analyses and transformations simpler and
11// more effective.
12//
13// Loop pre-header insertion guarantees that there is a single, non-critical
14// entry edge from outside of the loop to the loop header. This simplifies a
15// number of analyses and transformations, such as LICM.
16//
17// Loop exit-block insertion guarantees that all exit blocks from the loop
18// (blocks which are outside of the loop that have predecessors inside of the
19// loop) only have predecessors from inside of the loop (and are thus dominated
20// by the loop header). This simplifies transformations such as store-sinking
21// that are built into LICM.
22//
23// This pass also guarantees that loops will have exactly one backedge.
24//
25// Indirectbr instructions introduce several complications. If the loop
26// contains or is entered by an indirectbr instruction, it may not be possible
27// to transform the loop and make these guarantees. Client code should check
28// that these conditions are true before relying on them.
29//
30// Similar complications arise from callbr instructions, particularly in
31// asm-goto where blockaddress expressions are used.
32//
33// Note that the simplifycfg pass will clean up blocks which are split out but
34// end up being unnecessary, so usage of this pass should not pessimize
35// generated code.
36//
37// This pass obviously modifies the CFG, but updates loop information and
38// dominator information.
39//
40//===----------------------------------------------------------------------===//
41
42#include "llvm/Transforms/Utils/LoopSimplify.h"
43#include "llvm/ADT/DepthFirstIterator.h"
44#include "llvm/ADT/SetOperations.h"
45#include "llvm/ADT/SetVector.h"
46#include "llvm/ADT/SmallVector.h"
47#include "llvm/ADT/Statistic.h"
48#include "llvm/Analysis/AliasAnalysis.h"
49#include "llvm/Analysis/AssumptionCache.h"
50#include "llvm/Analysis/BasicAliasAnalysis.h"
51#include "llvm/Analysis/BranchProbabilityInfo.h"
52#include "llvm/Analysis/DependenceAnalysis.h"
53#include "llvm/Analysis/GlobalsModRef.h"
54#include "llvm/Analysis/InstructionSimplify.h"
55#include "llvm/Analysis/LoopInfo.h"
56#include "llvm/Analysis/MemorySSA.h"
57#include "llvm/Analysis/MemorySSAUpdater.h"
58#include "llvm/Analysis/ScalarEvolution.h"
59#include "llvm/Analysis/ScalarEvolutionAliasAnalysis.h"
60#include "llvm/IR/CFG.h"
61#include "llvm/IR/Constants.h"
62#include "llvm/IR/DataLayout.h"
63#include "llvm/IR/Dominators.h"
64#include "llvm/IR/Function.h"
65#include "llvm/IR/Instructions.h"
66#include "llvm/IR/IntrinsicInst.h"
67#include "llvm/IR/LLVMContext.h"
68#include "llvm/IR/Module.h"
69#include "llvm/IR/Type.h"
70#include "llvm/InitializePasses.h"
71#include "llvm/Support/Debug.h"
72#include "llvm/Support/raw_ostream.h"
73#include "llvm/Transforms/Utils.h"
74#include "llvm/Transforms/Utils/BasicBlockUtils.h"
75#include "llvm/Transforms/Utils/Local.h"
76#include "llvm/Transforms/Utils/LoopUtils.h"
77using namespace llvm;
78
79#define DEBUG_TYPE"loop-simplify" "loop-simplify"
80
81STATISTIC(NumNested , "Number of nested loops split out")static llvm::Statistic NumNested = {"loop-simplify", "NumNested"
, "Number of nested loops split out"}
;
82
83// If the block isn't already, move the new block to right after some 'outside
84// block' block. This prevents the preheader from being placed inside the loop
85// body, e.g. when the loop hasn't been rotated.
86static void placeSplitBlockCarefully(BasicBlock *NewBB,
87 SmallVectorImpl<BasicBlock *> &SplitPreds,
88 Loop *L) {
89 // Check to see if NewBB is already well placed.
90 Function::iterator BBI = --NewBB->getIterator();
91 for (unsigned i = 0, e = SplitPreds.size(); i != e; ++i) {
92 if (&*BBI == SplitPreds[i])
93 return;
94 }
95
96 // If it isn't already after an outside block, move it after one. This is
97 // always good as it makes the uncond branch from the outside block into a
98 // fall-through.
99
100 // Figure out *which* outside block to put this after. Prefer an outside
101 // block that neighbors a BB actually in the loop.
102 BasicBlock *FoundBB = nullptr;
103 for (unsigned i = 0, e = SplitPreds.size(); i != e; ++i) {
104 Function::iterator BBI = SplitPreds[i]->getIterator();
105 if (++BBI != NewBB->getParent()->end() && L->contains(&*BBI)) {
106 FoundBB = SplitPreds[i];
107 break;
108 }
109 }
110
111 // If our heuristic for a *good* bb to place this after doesn't find
112 // anything, just pick something. It's likely better than leaving it within
113 // the loop.
114 if (!FoundBB)
115 FoundBB = SplitPreds[0];
116 NewBB->moveAfter(FoundBB);
117}
118
119/// InsertPreheaderForLoop - Once we discover that a loop doesn't have a
120/// preheader, this method is called to insert one. This method has two phases:
121/// preheader insertion and analysis updating.
122///
123BasicBlock *llvm::InsertPreheaderForLoop(Loop *L, DominatorTree *DT,
124 LoopInfo *LI, MemorySSAUpdater *MSSAU,
125 bool PreserveLCSSA) {
126 BasicBlock *Header = L->getHeader();
127
128 // Compute the set of predecessors of the loop that are not in the loop.
129 SmallVector<BasicBlock*, 8> OutsideBlocks;
130 for (BasicBlock *P : predecessors(Header)) {
131 if (!L->contains(P)) { // Coming in from outside the loop?
132 // If the loop is branched to from an indirect terminator, we won't
133 // be able to fully transform the loop, because it prohibits
134 // edge splitting.
135 if (P->getTerminator()->isIndirectTerminator())
136 return nullptr;
137
138 // Keep track of it.
139 OutsideBlocks.push_back(P);
140 }
141 }
142
143 // Split out the loop pre-header.
144 BasicBlock *PreheaderBB;
145 PreheaderBB = SplitBlockPredecessors(Header, OutsideBlocks, ".preheader", DT,
146 LI, MSSAU, PreserveLCSSA);
147 if (!PreheaderBB)
148 return nullptr;
149
150 LLVM_DEBUG(dbgs() << "LoopSimplify: Creating pre-header "do { } while (false)
151 << PreheaderBB->getName() << "\n")do { } while (false);
152
153 // Make sure that NewBB is put someplace intelligent, which doesn't mess up
154 // code layout too horribly.
155 placeSplitBlockCarefully(PreheaderBB, OutsideBlocks, L);
156
157 return PreheaderBB;
158}
159
160/// Add the specified block, and all of its predecessors, to the specified set,
161/// if it's not already in there. Stop predecessor traversal when we reach
162/// StopBlock.
163static void addBlockAndPredsToSet(BasicBlock *InputBB, BasicBlock *StopBlock,
164 SmallPtrSetImpl<BasicBlock *> &Blocks) {
165 SmallVector<BasicBlock *, 8> Worklist;
166 Worklist.push_back(InputBB);
167 do {
168 BasicBlock *BB = Worklist.pop_back_val();
169 if (Blocks.insert(BB).second && BB != StopBlock)
170 // If BB is not already processed and it is not a stop block then
171 // insert its predecessor in the work list
172 append_range(Worklist, predecessors(BB));
173 } while (!Worklist.empty());
174}
175
176/// The first part of loop-nestification is to find a PHI node that tells
177/// us how to partition the loops.
178static PHINode *findPHIToPartitionLoops(Loop *L, DominatorTree *DT,
179 AssumptionCache *AC) {
180 const DataLayout &DL = L->getHeader()->getModule()->getDataLayout();
181 for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ) {
182 PHINode *PN = cast<PHINode>(I);
183 ++I;
184 if (Value *V = SimplifyInstruction(PN, {DL, nullptr, DT, AC})) {
185 // This is a degenerate PHI already, don't modify it!
186 PN->replaceAllUsesWith(V);
187 PN->eraseFromParent();
188 continue;
189 }
190
191 // Scan this PHI node looking for a use of the PHI node by itself.
192 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
193 if (PN->getIncomingValue(i) == PN &&
194 L->contains(PN->getIncomingBlock(i)))
195 // We found something tasty to remove.
196 return PN;
197 }
198 return nullptr;
199}
200
201/// If this loop has multiple backedges, try to pull one of them out into
202/// a nested loop.
203///
204/// This is important for code that looks like
205/// this:
206///
207/// Loop:
208/// ...
209/// br cond, Loop, Next
210/// ...
211/// br cond2, Loop, Out
212///
213/// To identify this common case, we look at the PHI nodes in the header of the
214/// loop. PHI nodes with unchanging values on one backedge correspond to values
215/// that change in the "outer" loop, but not in the "inner" loop.
216///
217/// If we are able to separate out a loop, return the new outer loop that was
218/// created.
219///
220static Loop *separateNestedLoop(Loop *L, BasicBlock *Preheader,
221 DominatorTree *DT, LoopInfo *LI,
222 ScalarEvolution *SE, bool PreserveLCSSA,
223 AssumptionCache *AC, MemorySSAUpdater *MSSAU) {
224 // Don't try to separate loops without a preheader.
225 if (!Preheader)
226 return nullptr;
227
228 // Treat the presence of convergent functions conservatively. The
229 // transformation is invalid if calls to certain convergent
230 // functions (like an AMDGPU barrier) get included in the resulting
231 // inner loop. But blocks meant for the inner loop will be
232 // identified later at a point where it's too late to abort the
233 // transformation. Also, the convergent attribute is not really
234 // sufficient to express the semantics of functions that are
235 // affected by this transformation. So we choose to back off if such
236 // a function call is present until a better alternative becomes
237 // available. This is similar to the conservative treatment of
238 // convergent function calls in GVNHoist and JumpThreading.
239 for (auto BB : L->blocks()) {
240 for (auto &II : *BB) {
241 if (auto CI = dyn_cast<CallBase>(&II)) {
242 if (CI->isConvergent()) {
243 return nullptr;
244 }
245 }
246 }
247 }
248
249 // The header is not a landing pad; preheader insertion should ensure this.
250 BasicBlock *Header = L->getHeader();
251 assert(!Header->isEHPad() && "Can't insert backedge to EH pad")((void)0);
252
253 PHINode *PN = findPHIToPartitionLoops(L, DT, AC);
254 if (!PN) return nullptr; // No known way to partition.
255
256 // Pull out all predecessors that have varying values in the loop. This
257 // handles the case when a PHI node has multiple instances of itself as
258 // arguments.
259 SmallVector<BasicBlock*, 8> OuterLoopPreds;
260 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
261 if (PN->getIncomingValue(i) != PN ||
262 !L->contains(PN->getIncomingBlock(i))) {
263 // We can't split indirect control flow edges.
264 if (PN->getIncomingBlock(i)->getTerminator()->isIndirectTerminator())
265 return nullptr;
266 OuterLoopPreds.push_back(PN->getIncomingBlock(i));
267 }
268 }
269 LLVM_DEBUG(dbgs() << "LoopSimplify: Splitting out a new outer loop\n")do { } while (false);
270
271 // If ScalarEvolution is around and knows anything about values in
272 // this loop, tell it to forget them, because we're about to
273 // substantially change it.
274 if (SE)
275 SE->forgetLoop(L);
276
277 BasicBlock *NewBB = SplitBlockPredecessors(Header, OuterLoopPreds, ".outer",
278 DT, LI, MSSAU, PreserveLCSSA);
279
280 // Make sure that NewBB is put someplace intelligent, which doesn't mess up
281 // code layout too horribly.
282 placeSplitBlockCarefully(NewBB, OuterLoopPreds, L);
283
284 // Create the new outer loop.
285 Loop *NewOuter = LI->AllocateLoop();
286
287 // Change the parent loop to use the outer loop as its child now.
288 if (Loop *Parent = L->getParentLoop())
289 Parent->replaceChildLoopWith(L, NewOuter);
290 else
291 LI->changeTopLevelLoop(L, NewOuter);
292
293 // L is now a subloop of our outer loop.
294 NewOuter->addChildLoop(L);
295
296 for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
297 I != E; ++I)
298 NewOuter->addBlockEntry(*I);
299
300 // Now reset the header in L, which had been moved by
301 // SplitBlockPredecessors for the outer loop.
302 L->moveToHeader(Header);
303
304 // Determine which blocks should stay in L and which should be moved out to
305 // the Outer loop now.
306 SmallPtrSet<BasicBlock *, 4> BlocksInL;
307 for (BasicBlock *P : predecessors(Header)) {
308 if (DT->dominates(Header, P))
309 addBlockAndPredsToSet(P, Header, BlocksInL);
310 }
311
312 // Scan all of the loop children of L, moving them to OuterLoop if they are
313 // not part of the inner loop.
314 const std::vector<Loop*> &SubLoops = L->getSubLoops();
315 for (size_t I = 0; I != SubLoops.size(); )
316 if (BlocksInL.count(SubLoops[I]->getHeader()))
317 ++I; // Loop remains in L
318 else
319 NewOuter->addChildLoop(L->removeChildLoop(SubLoops.begin() + I));
320
321 SmallVector<BasicBlock *, 8> OuterLoopBlocks;
322 OuterLoopBlocks.push_back(NewBB);
323 // Now that we know which blocks are in L and which need to be moved to
324 // OuterLoop, move any blocks that need it.
325 for (unsigned i = 0; i != L->getBlocks().size(); ++i) {
326 BasicBlock *BB = L->getBlocks()[i];
327 if (!BlocksInL.count(BB)) {
328 // Move this block to the parent, updating the exit blocks sets
329 L->removeBlockFromLoop(BB);
330 if ((*LI)[BB] == L) {
331 LI->changeLoopFor(BB, NewOuter);
332 OuterLoopBlocks.push_back(BB);
333 }
334 --i;
335 }
336 }
337
338 // Split edges to exit blocks from the inner loop, if they emerged in the
339 // process of separating the outer one.
340 formDedicatedExitBlocks(L, DT, LI, MSSAU, PreserveLCSSA);
341
342 if (PreserveLCSSA) {
343 // Fix LCSSA form for L. Some values, which previously were only used inside
344 // L, can now be used in NewOuter loop. We need to insert phi-nodes for them
345 // in corresponding exit blocks.
346 // We don't need to form LCSSA recursively, because there cannot be uses
347 // inside a newly created loop of defs from inner loops as those would
348 // already be a use of an LCSSA phi node.
349 formLCSSA(*L, *DT, LI, SE);
350
351 assert(NewOuter->isRecursivelyLCSSAForm(*DT, *LI) &&((void)0)
352 "LCSSA is broken after separating nested loops!")((void)0);
353 }
354
355 return NewOuter;
356}
357
358/// This method is called when the specified loop has more than one
359/// backedge in it.
360///
361/// If this occurs, revector all of these backedges to target a new basic block
362/// and have that block branch to the loop header. This ensures that loops
363/// have exactly one backedge.
364static BasicBlock *insertUniqueBackedgeBlock(Loop *L, BasicBlock *Preheader,
365 DominatorTree *DT, LoopInfo *LI,
366 MemorySSAUpdater *MSSAU) {
367 assert(L->getNumBackEdges() > 1 && "Must have > 1 backedge!")((void)0);
368
369 // Get information about the loop
370 BasicBlock *Header = L->getHeader();
371 Function *F = Header->getParent();
372
373 // Unique backedge insertion currently depends on having a preheader.
374 if (!Preheader
13.1
'Preheader' is non-null
13.1
'Preheader' is non-null
13.1
'Preheader' is non-null
)
14
Taking false branch
375 return nullptr;
376
377 // The header is not an EH pad; preheader insertion should ensure this.
378 assert(!Header->isEHPad() && "Can't insert backedge to EH pad")((void)0);
379
380 // Figure out which basic blocks contain back-edges to the loop header.
381 std::vector<BasicBlock*> BackedgeBlocks;
382 for (BasicBlock *P : predecessors(Header)) {
383 // Indirect edges cannot be split, so we must fail if we find one.
384 if (P->getTerminator()->isIndirectTerminator())
385 return nullptr;
386
387 if (P != Preheader) BackedgeBlocks.push_back(P);
388 }
389
390 // Create and insert the new backedge block...
391 BasicBlock *BEBlock = BasicBlock::Create(Header->getContext(),
392 Header->getName() + ".backedge", F);
393 BranchInst *BETerminator = BranchInst::Create(Header, BEBlock);
394 BETerminator->setDebugLoc(Header->getFirstNonPHI()->getDebugLoc());
395
396 LLVM_DEBUG(dbgs() << "LoopSimplify: Inserting unique backedge block "do { } while (false)
15
Loop condition is false. Exiting loop
397 << BEBlock->getName() << "\n")do { } while (false);
398
399 // Move the new backedge block to right after the last backedge block.
400 Function::iterator InsertPos = ++BackedgeBlocks.back()->getIterator();
401 F->getBasicBlockList().splice(InsertPos, F->getBasicBlockList(), BEBlock);
402
403 // Now that the block has been inserted into the function, create PHI nodes in
404 // the backedge block which correspond to any PHI nodes in the header block.
405 for (BasicBlock::iterator I = Header->begin(); isa<PHINode>(I); ++I) {
16
Assuming 'I' is not a 'PHINode'
17
Loop condition is false. Execution continues on line 457
406 PHINode *PN = cast<PHINode>(I);
407 PHINode *NewPN = PHINode::Create(PN->getType(), BackedgeBlocks.size(),
408 PN->getName()+".be", BETerminator);
409
410 // Loop over the PHI node, moving all entries except the one for the
411 // preheader over to the new PHI node.
412 unsigned PreheaderIdx = ~0U;
413 bool HasUniqueIncomingValue = true;
414 Value *UniqueValue = nullptr;
415 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
416 BasicBlock *IBB = PN->getIncomingBlock(i);
417 Value *IV = PN->getIncomingValue(i);
418 if (IBB == Preheader) {
419 PreheaderIdx = i;
420 } else {
421 NewPN->addIncoming(IV, IBB);
422 if (HasUniqueIncomingValue) {
423 if (!UniqueValue)
424 UniqueValue = IV;
425 else if (UniqueValue != IV)
426 HasUniqueIncomingValue = false;
427 }
428 }
429 }
430
431 // Delete all of the incoming values from the old PN except the preheader's
432 assert(PreheaderIdx != ~0U && "PHI has no preheader entry??")((void)0);
433 if (PreheaderIdx != 0) {
434 PN->setIncomingValue(0, PN->getIncomingValue(PreheaderIdx));
435 PN->setIncomingBlock(0, PN->getIncomingBlock(PreheaderIdx));
436 }
437 // Nuke all entries except the zero'th.
438 for (unsigned i = 0, e = PN->getNumIncomingValues()-1; i != e; ++i)
439 PN->removeIncomingValue(e-i, false);
440
441 // Finally, add the newly constructed PHI node as the entry for the BEBlock.
442 PN->addIncoming(NewPN, BEBlock);
443
444 // As an optimization, if all incoming values in the new PhiNode (which is a
445 // subset of the incoming values of the old PHI node) have the same value,
446 // eliminate the PHI Node.
447 if (HasUniqueIncomingValue) {
448 NewPN->replaceAllUsesWith(UniqueValue);
449 BEBlock->getInstList().erase(NewPN);
450 }
451 }
452
453 // Now that all of the PHI nodes have been inserted and adjusted, modify the
454 // backedge blocks to jump to the BEBlock instead of the header.
455 // If one of the backedges has llvm.loop metadata attached, we remove
456 // it from the backedge and add it to BEBlock.
457 unsigned LoopMDKind = BEBlock->getContext().getMDKindID("llvm.loop");
458 MDNode *LoopMD = nullptr;
459 for (unsigned i = 0, e = BackedgeBlocks.size(); i != e; ++i) {
18
Assuming 'i' is equal to 'e'
19
Loop condition is false. Execution continues on line 466
460 Instruction *TI = BackedgeBlocks[i]->getTerminator();
461 if (!LoopMD)
462 LoopMD = TI->getMetadata(LoopMDKind);
463 TI->setMetadata(LoopMDKind, nullptr);
464 TI->replaceSuccessorWith(Header, BEBlock);
465 }
466 BEBlock->getTerminator()->setMetadata(LoopMDKind, LoopMD);
467
468 //===--- Update all analyses which we must preserve now -----------------===//
469
470 // Update Loop Information - we know that this block is now in the current
471 // loop and all parent loops.
472 L->addBasicBlockToLoop(BEBlock, *LI);
473
474 // Update dominator information
475 DT->splitBlock(BEBlock);
20
Calling 'DominatorTreeBase::splitBlock'
476
477 if (MSSAU)
478 MSSAU->updatePhisWhenInsertingUniqueBackedgeBlock(Header, Preheader,
479 BEBlock);
480
481 return BEBlock;
482}
483
484/// Simplify one loop and queue further loops for simplification.
485static bool simplifyOneLoop(Loop *L, SmallVectorImpl<Loop *> &Worklist,
486 DominatorTree *DT, LoopInfo *LI,
487 ScalarEvolution *SE, AssumptionCache *AC,
488 MemorySSAUpdater *MSSAU, bool PreserveLCSSA) {
489 bool Changed = false;
490 if (MSSAU && VerifyMemorySSA)
1
Assuming 'MSSAU' is null
491 MSSAU->getMemorySSA()->verifyMemorySSA();
492
493ReprocessLoop:
494
495 // Check to see that no blocks (other than the header) in this loop have
496 // predecessors that are not in the loop. This is not valid for natural
497 // loops, but can occur if the blocks are unreachable. Since they are
498 // unreachable we can just shamelessly delete those CFG edges!
499 for (Loop::block_iterator BB = L->block_begin(), E = L->block_end();
3
Loop condition is false. Execution continues on line 522
500 BB != E; ++BB) {
2
Assuming 'BB' is equal to 'E'
501 if (*BB == L->getHeader()) continue;
502
503 SmallPtrSet<BasicBlock*, 4> BadPreds;
504 for (BasicBlock *P : predecessors(*BB))
505 if (!L->contains(P))
506 BadPreds.insert(P);
507
508 // Delete each unique out-of-loop (and thus dead) predecessor.
509 for (BasicBlock *P : BadPreds) {
510
511 LLVM_DEBUG(dbgs() << "LoopSimplify: Deleting edge from dead predecessor "do { } while (false)
512 << P->getName() << "\n")do { } while (false);
513
514 // Zap the dead pred's terminator and replace it with unreachable.
515 Instruction *TI = P->getTerminator();
516 changeToUnreachable(TI, PreserveLCSSA,
517 /*DTU=*/nullptr, MSSAU);
518 Changed = true;
519 }
520 }
521
522 if (MSSAU
3.1
'MSSAU' is null
3.1
'MSSAU' is null
3.1
'MSSAU' is null
&& VerifyMemorySSA)
523 MSSAU->getMemorySSA()->verifyMemorySSA();
524
525 // If there are exiting blocks with branches on undef, resolve the undef in
526 // the direction which will exit the loop. This will help simplify loop
527 // trip count computations.
528 SmallVector<BasicBlock*, 8> ExitingBlocks;
529 L->getExitingBlocks(ExitingBlocks);
530 for (BasicBlock *ExitingBlock : ExitingBlocks)
4
Assuming '__begin1' is equal to '__end1'
531 if (BranchInst *BI = dyn_cast<BranchInst>(ExitingBlock->getTerminator()))
532 if (BI->isConditional()) {
533 if (UndefValue *Cond = dyn_cast<UndefValue>(BI->getCondition())) {
534
535 LLVM_DEBUG(dbgs()do { } while (false)
536 << "LoopSimplify: Resolving \"br i1 undef\" to exit in "do { } while (false)
537 << ExitingBlock->getName() << "\n")do { } while (false);
538
539 BI->setCondition(ConstantInt::get(Cond->getType(),
540 !L->contains(BI->getSuccessor(0))));
541
542 Changed = true;
543 }
544 }
545
546 // Does the loop already have a preheader? If so, don't insert one.
547 BasicBlock *Preheader = L->getLoopPreheader();
548 if (!Preheader) {
5
Assuming 'Preheader' is non-null
6
Taking false branch
549 Preheader = InsertPreheaderForLoop(L, DT, LI, MSSAU, PreserveLCSSA);
550 if (Preheader)
551 Changed = true;
552 }
553
554 // Next, check to make sure that all exit nodes of the loop only have
555 // predecessors that are inside of the loop. This check guarantees that the
556 // loop preheader/header will dominate the exit blocks. If the exit block has
557 // predecessors from outside of the loop, split the edge now.
558 if (formDedicatedExitBlocks(L, DT, LI, MSSAU, PreserveLCSSA))
7
Assuming the condition is false
8
Taking false branch
559 Changed = true;
560
561 if (MSSAU
8.1
'MSSAU' is null
8.1
'MSSAU' is null
8.1
'MSSAU' is null
&& VerifyMemorySSA)
562 MSSAU->getMemorySSA()->verifyMemorySSA();
563
564 // If the header has more than two predecessors at this point (from the
565 // preheader and from multiple backedges), we must adjust the loop.
566 BasicBlock *LoopLatch = L->getLoopLatch();
567 if (!LoopLatch) {
9
Assuming 'LoopLatch' is null
10
Taking true branch
568 // If this is really a nested loop, rip it out into a child loop. Don't do
569 // this for loops with a giant number of backedges, just factor them into a
570 // common backedge instead.
571 if (L->getNumBackEdges() < 8) {
11
Assuming the condition is false
12
Taking false branch
572 if (Loop *OuterL = separateNestedLoop(L, Preheader, DT, LI, SE,
573 PreserveLCSSA, AC, MSSAU)) {
574 ++NumNested;
575 // Enqueue the outer loop as it should be processed next in our
576 // depth-first nest walk.
577 Worklist.push_back(OuterL);
578
579 // This is a big restructuring change, reprocess the whole loop.
580 Changed = true;
581 // GCC doesn't tail recursion eliminate this.
582 // FIXME: It isn't clear we can't rely on LLVM to TRE this.
583 goto ReprocessLoop;
584 }
585 }
586
587 // If we either couldn't, or didn't want to, identify nesting of the loops,
588 // insert a new block that all backedges target, then make it jump to the
589 // loop header.
590 LoopLatch = insertUniqueBackedgeBlock(L, Preheader, DT, LI, MSSAU);
13
Calling 'insertUniqueBackedgeBlock'
591 if (LoopLatch)
592 Changed = true;
593 }
594
595 if (MSSAU && VerifyMemorySSA)
596 MSSAU->getMemorySSA()->verifyMemorySSA();
597
598 const DataLayout &DL = L->getHeader()->getModule()->getDataLayout();
599
600 // Scan over the PHI nodes in the loop header. Since they now have only two
601 // incoming values (the loop is canonicalized), we may have simplified the PHI
602 // down to 'X = phi [X, Y]', which should be replaced with 'Y'.
603 PHINode *PN;
604 for (BasicBlock::iterator I = L->getHeader()->begin();
605 (PN = dyn_cast<PHINode>(I++)); )
606 if (Value *V = SimplifyInstruction(PN, {DL, nullptr, DT, AC})) {
607 if (SE) SE->forgetValue(PN);
608 if (!PreserveLCSSA || LI->replacementPreservesLCSSAForm(PN, V)) {
609 PN->replaceAllUsesWith(V);
610 PN->eraseFromParent();
611 Changed = true;
612 }
613 }
614
615 // If this loop has multiple exits and the exits all go to the same
616 // block, attempt to merge the exits. This helps several passes, such
617 // as LoopRotation, which do not support loops with multiple exits.
618 // SimplifyCFG also does this (and this code uses the same utility
619 // function), however this code is loop-aware, where SimplifyCFG is
620 // not. That gives it the advantage of being able to hoist
621 // loop-invariant instructions out of the way to open up more
622 // opportunities, and the disadvantage of having the responsibility
623 // to preserve dominator information.
624 auto HasUniqueExitBlock = [&]() {
625 BasicBlock *UniqueExit = nullptr;
626 for (auto *ExitingBB : ExitingBlocks)
627 for (auto *SuccBB : successors(ExitingBB)) {
628 if (L->contains(SuccBB))
629 continue;
630
631 if (!UniqueExit)
632 UniqueExit = SuccBB;
633 else if (UniqueExit != SuccBB)
634 return false;
635 }
636
637 return true;
638 };
639 if (HasUniqueExitBlock()) {
640 for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) {
641 BasicBlock *ExitingBlock = ExitingBlocks[i];
642 if (!ExitingBlock->getSinglePredecessor()) continue;
643 BranchInst *BI = dyn_cast<BranchInst>(ExitingBlock->getTerminator());
644 if (!BI || !BI->isConditional()) continue;
645 CmpInst *CI = dyn_cast<CmpInst>(BI->getCondition());
646 if (!CI || CI->getParent() != ExitingBlock) continue;
647
648 // Attempt to hoist out all instructions except for the
649 // comparison and the branch.
650 bool AllInvariant = true;
651 bool AnyInvariant = false;
652 for (auto I = ExitingBlock->instructionsWithoutDebug().begin(); &*I != BI; ) {
653 Instruction *Inst = &*I++;
654 if (Inst == CI)
655 continue;
656 if (!L->makeLoopInvariant(
657 Inst, AnyInvariant,
658 Preheader ? Preheader->getTerminator() : nullptr, MSSAU)) {
659 AllInvariant = false;
660 break;
661 }
662 }
663 if (AnyInvariant) {
664 Changed = true;
665 // The loop disposition of all SCEV expressions that depend on any
666 // hoisted values have also changed.
667 if (SE)
668 SE->forgetLoopDispositions(L);
669 }
670 if (!AllInvariant) continue;
671
672 // The block has now been cleared of all instructions except for
673 // a comparison and a conditional branch. SimplifyCFG may be able
674 // to fold it now.
675 if (!FoldBranchToCommonDest(BI, /*DTU=*/nullptr, MSSAU))
676 continue;
677
678 // Success. The block is now dead, so remove it from the loop,
679 // update the dominator tree and delete it.
680 LLVM_DEBUG(dbgs() << "LoopSimplify: Eliminating exiting block "do { } while (false)
681 << ExitingBlock->getName() << "\n")do { } while (false);
682
683 assert(pred_empty(ExitingBlock))((void)0);
684 Changed = true;
685 LI->removeBlock(ExitingBlock);
686
687 DomTreeNode *Node = DT->getNode(ExitingBlock);
688 while (!Node->isLeaf()) {
689 DomTreeNode *Child = Node->back();
690 DT->changeImmediateDominator(Child, Node->getIDom());
691 }
692 DT->eraseNode(ExitingBlock);
693 if (MSSAU) {
694 SmallSetVector<BasicBlock *, 8> ExitBlockSet;
695 ExitBlockSet.insert(ExitingBlock);
696 MSSAU->removeBlocks(ExitBlockSet);
697 }
698
699 BI->getSuccessor(0)->removePredecessor(
700 ExitingBlock, /* KeepOneInputPHIs */ PreserveLCSSA);
701 BI->getSuccessor(1)->removePredecessor(
702 ExitingBlock, /* KeepOneInputPHIs */ PreserveLCSSA);
703 ExitingBlock->eraseFromParent();
704 }
705 }
706
707 // Changing exit conditions for blocks may affect exit counts of this loop and
708 // any of its paretns, so we must invalidate the entire subtree if we've made
709 // any changes.
710 if (Changed && SE)
711 SE->forgetTopmostLoop(L);
712
713 if (MSSAU && VerifyMemorySSA)
714 MSSAU->getMemorySSA()->verifyMemorySSA();
715
716 return Changed;
717}
718
719bool llvm::simplifyLoop(Loop *L, DominatorTree *DT, LoopInfo *LI,
720 ScalarEvolution *SE, AssumptionCache *AC,
721 MemorySSAUpdater *MSSAU, bool PreserveLCSSA) {
722 bool Changed = false;
723
724#ifndef NDEBUG1
725 // If we're asked to preserve LCSSA, the loop nest needs to start in LCSSA
726 // form.
727 if (PreserveLCSSA) {
728 assert(DT && "DT not available.")((void)0);
729 assert(LI && "LI not available.")((void)0);
730 assert(L->isRecursivelyLCSSAForm(*DT, *LI) &&((void)0)
731 "Requested to preserve LCSSA, but it's already broken.")((void)0);
732 }
733#endif
734
735 // Worklist maintains our depth-first queue of loops in this nest to process.
736 SmallVector<Loop *, 4> Worklist;
737 Worklist.push_back(L);
738
739 // Walk the worklist from front to back, pushing newly found sub loops onto
740 // the back. This will let us process loops from back to front in depth-first
741 // order. We can use this simple process because loops form a tree.
742 for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) {
743 Loop *L2 = Worklist[Idx];
744 Worklist.append(L2->begin(), L2->end());
745 }
746
747 while (!Worklist.empty())
748 Changed |= simplifyOneLoop(Worklist.pop_back_val(), Worklist, DT, LI, SE,
749 AC, MSSAU, PreserveLCSSA);
750
751 return Changed;
752}
753
754namespace {
755 struct LoopSimplify : public FunctionPass {
756 static char ID; // Pass identification, replacement for typeid
757 LoopSimplify() : FunctionPass(ID) {
758 initializeLoopSimplifyPass(*PassRegistry::getPassRegistry());
759 }
760
761 bool runOnFunction(Function &F) override;
762
763 void getAnalysisUsage(AnalysisUsage &AU) const override {
764 AU.addRequired<AssumptionCacheTracker>();
765
766 // We need loop information to identify the loops...
767 AU.addRequired<DominatorTreeWrapperPass>();
768 AU.addPreserved<DominatorTreeWrapperPass>();
769
770 AU.addRequired<LoopInfoWrapperPass>();
771 AU.addPreserved<LoopInfoWrapperPass>();
772
773 AU.addPreserved<BasicAAWrapperPass>();
774 AU.addPreserved<AAResultsWrapperPass>();
775 AU.addPreserved<GlobalsAAWrapperPass>();
776 AU.addPreserved<ScalarEvolutionWrapperPass>();
777 AU.addPreserved<SCEVAAWrapperPass>();
778 AU.addPreservedID(LCSSAID);
779 AU.addPreserved<DependenceAnalysisWrapperPass>();
780 AU.addPreservedID(BreakCriticalEdgesID); // No critical edges added.
781 AU.addPreserved<BranchProbabilityInfoWrapperPass>();
782 if (EnableMSSALoopDependency)
783 AU.addPreserved<MemorySSAWrapperPass>();
784 }
785
786 /// verifyAnalysis() - Verify LoopSimplifyForm's guarantees.
787 void verifyAnalysis() const override;
788 };
789}
790
791char LoopSimplify::ID = 0;
792INITIALIZE_PASS_BEGIN(LoopSimplify, "loop-simplify",static void *initializeLoopSimplifyPassOnce(PassRegistry &
Registry) {
793 "Canonicalize natural loops", false, false)static void *initializeLoopSimplifyPassOnce(PassRegistry &
Registry) {
794INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)initializeAssumptionCacheTrackerPass(Registry);
795INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);
796INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)initializeLoopInfoWrapperPassPass(Registry);
797INITIALIZE_PASS_END(LoopSimplify, "loop-simplify",PassInfo *PI = new PassInfo( "Canonicalize natural loops", "loop-simplify"
, &LoopSimplify::ID, PassInfo::NormalCtor_t(callDefaultCtor
<LoopSimplify>), false, false); Registry.registerPass(*
PI, true); return PI; } static llvm::once_flag InitializeLoopSimplifyPassFlag
; void llvm::initializeLoopSimplifyPass(PassRegistry &Registry
) { llvm::call_once(InitializeLoopSimplifyPassFlag, initializeLoopSimplifyPassOnce
, std::ref(Registry)); }
798 "Canonicalize natural loops", false, false)PassInfo *PI = new PassInfo( "Canonicalize natural loops", "loop-simplify"
, &LoopSimplify::ID, PassInfo::NormalCtor_t(callDefaultCtor
<LoopSimplify>), false, false); Registry.registerPass(*
PI, true); return PI; } static llvm::once_flag InitializeLoopSimplifyPassFlag
; void llvm::initializeLoopSimplifyPass(PassRegistry &Registry
) { llvm::call_once(InitializeLoopSimplifyPassFlag, initializeLoopSimplifyPassOnce
, std::ref(Registry)); }
799
800// Publicly exposed interface to pass...
801char &llvm::LoopSimplifyID = LoopSimplify::ID;
802Pass *llvm::createLoopSimplifyPass() { return new LoopSimplify(); }
803
804/// runOnFunction - Run down all loops in the CFG (recursively, but we could do
805/// it in any convenient order) inserting preheaders...
806///
807bool LoopSimplify::runOnFunction(Function &F) {
808 bool Changed = false;
809 LoopInfo *LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
810 DominatorTree *DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
811 auto *SEWP = getAnalysisIfAvailable<ScalarEvolutionWrapperPass>();
812 ScalarEvolution *SE = SEWP ? &SEWP->getSE() : nullptr;
813 AssumptionCache *AC =
814 &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
815 MemorySSA *MSSA = nullptr;
816 std::unique_ptr<MemorySSAUpdater> MSSAU;
817 if (EnableMSSALoopDependency) {
818 auto *MSSAAnalysis = getAnalysisIfAvailable<MemorySSAWrapperPass>();
819 if (MSSAAnalysis) {
820 MSSA = &MSSAAnalysis->getMSSA();
821 MSSAU = std::make_unique<MemorySSAUpdater>(MSSA);
822 }
823 }
824
825 bool PreserveLCSSA = mustPreserveAnalysisID(LCSSAID);
826
827 // Simplify each loop nest in the function.
828 for (auto *L : *LI)
829 Changed |= simplifyLoop(L, DT, LI, SE, AC, MSSAU.get(), PreserveLCSSA);
830
831#ifndef NDEBUG1
832 if (PreserveLCSSA) {
833 bool InLCSSA = all_of(
834 *LI, [&](Loop *L) { return L->isRecursivelyLCSSAForm(*DT, *LI); });
835 assert(InLCSSA && "LCSSA is broken after loop-simplify.")((void)0);
836 }
837#endif
838 return Changed;
839}
840
841PreservedAnalyses LoopSimplifyPass::run(Function &F,
842 FunctionAnalysisManager &AM) {
843 bool Changed = false;
844 LoopInfo *LI = &AM.getResult<LoopAnalysis>(F);
845 DominatorTree *DT = &AM.getResult<DominatorTreeAnalysis>(F);
846 ScalarEvolution *SE = AM.getCachedResult<ScalarEvolutionAnalysis>(F);
847 AssumptionCache *AC = &AM.getResult<AssumptionAnalysis>(F);
848 auto *MSSAAnalysis = AM.getCachedResult<MemorySSAAnalysis>(F);
849 std::unique_ptr<MemorySSAUpdater> MSSAU;
850 if (MSSAAnalysis) {
851 auto *MSSA = &MSSAAnalysis->getMSSA();
852 MSSAU = std::make_unique<MemorySSAUpdater>(MSSA);
853 }
854
855
856 // Note that we don't preserve LCSSA in the new PM, if you need it run LCSSA
857 // after simplifying the loops. MemorySSA is preserved if it exists.
858 for (auto *L : *LI)
859 Changed |=
860 simplifyLoop(L, DT, LI, SE, AC, MSSAU.get(), /*PreserveLCSSA*/ false);
861
862 if (!Changed)
863 return PreservedAnalyses::all();
864
865 PreservedAnalyses PA;
866 PA.preserve<DominatorTreeAnalysis>();
867 PA.preserve<LoopAnalysis>();
868 PA.preserve<ScalarEvolutionAnalysis>();
869 PA.preserve<DependenceAnalysis>();
870 if (MSSAAnalysis)
871 PA.preserve<MemorySSAAnalysis>();
872 // BPI maps conditional terminators to probabilities, LoopSimplify can insert
873 // blocks, but it does so only by splitting existing blocks and edges. This
874 // results in the interesting property that all new terminators inserted are
875 // unconditional branches which do not appear in BPI. All deletions are
876 // handled via ValueHandle callbacks w/in BPI.
877 PA.preserve<BranchProbabilityAnalysis>();
878 return PA;
879}
880
881// FIXME: Restore this code when we re-enable verification in verifyAnalysis
882// below.
883#if 0
884static void verifyLoop(Loop *L) {
885 // Verify subloops.
886 for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
887 verifyLoop(*I);
888
889 // It used to be possible to just assert L->isLoopSimplifyForm(), however
890 // with the introduction of indirectbr, there are now cases where it's
891 // not possible to transform a loop as necessary. We can at least check
892 // that there is an indirectbr near any time there's trouble.
893
894 // Indirectbr can interfere with preheader and unique backedge insertion.
895 if (!L->getLoopPreheader() || !L->getLoopLatch()) {
896 bool HasIndBrPred = false;
897 for (BasicBlock *Pred : predecessors(L->getHeader()))
898 if (isa<IndirectBrInst>(Pred->getTerminator())) {
899 HasIndBrPred = true;
900 break;
901 }
902 assert(HasIndBrPred &&((void)0)
903 "LoopSimplify has no excuse for missing loop header info!")((void)0);
904 (void)HasIndBrPred;
905 }
906
907 // Indirectbr can interfere with exit block canonicalization.
908 if (!L->hasDedicatedExits()) {
909 bool HasIndBrExiting = false;
910 SmallVector<BasicBlock*, 8> ExitingBlocks;
911 L->getExitingBlocks(ExitingBlocks);
912 for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) {
913 if (isa<IndirectBrInst>((ExitingBlocks[i])->getTerminator())) {
914 HasIndBrExiting = true;
915 break;
916 }
917 }
918
919 assert(HasIndBrExiting &&((void)0)
920 "LoopSimplify has no excuse for missing exit block info!")((void)0);
921 (void)HasIndBrExiting;
922 }
923}
924#endif
925
926void LoopSimplify::verifyAnalysis() const {
927 // FIXME: This routine is being called mid-way through the loop pass manager
928 // as loop passes destroy this analysis. That's actually fine, but we have no
929 // way of expressing that here. Once all of the passes that destroy this are
930 // hoisted out of the loop pass manager we can add back verification here.
931#if 0
932 for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I)
933 verifyLoop(*I);
934#endif
935}

/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; }
36
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())
43
Calling 'operator!='
49
Returning from 'operator!='
50
Taking true branch
354 return I->second.get();
51
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()) {
35
Calling 'DominatorTreeBase::isPostDominator'
37
Returning from 'DominatorTreeBase::isPostDominator'
38
Taking true branch
476 NodeT &Entry = A->getParent()->front();
477 if (A == &Entry || B == &Entry)
39
Assuming the condition is false
40
Assuming the condition is false
41
Taking false branch
478 return &Entry;
479 }
480
481 DomTreeNodeBase<NodeT> *NodeA = getNode(A);
42
Calling 'DominatorTreeBase::getNode'
52
Returning from 'DominatorTreeBase::getNode'
53
'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) {
54
Assuming 'NodeA' is equal to 'NodeB'
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
20.1
'IsPostDominator' is false
20.1
'IsPostDominator' is false
20.1
'IsPostDominator' is false
)
21
Taking false branch
702 Split<Inverse<NodeT *>>(NewBB);
703 else
704 Split<NodeT *>(NewBB);
22
Calling 'DominatorTreeBase::Split'
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)
23
Assuming the condition is true
24
Loop condition is true. Entering loop body
859 if (isReachableFromEntry(PredBlocks[i])) {
25
Assuming the condition is true
26
Taking true branch
860 NewBBIDom = PredBlocks[i];
861 break;
27
Execution continues on line 867
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;
28
Assuming 'NewBBIDom' is non-null
29
Taking false branch
868
869 for (i = i + 1; i < PredBlocks.size(); ++i) {
30
Assuming the condition is true
31
Loop condition is true. Entering loop body
870 if (isReachableFromEntry(PredBlocks[i]))
32
Assuming the condition is true
33
Taking true branch
871 NewBBIDom = findNearestCommonDominator(NewBBIDom, PredBlocks[i]);
34
Calling 'DominatorTreeBase::findNearestCommonDominator'
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;
45
Assuming 'LHS.Ptr' is not equal to 'RHS.Ptr'
46
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);
44
Calling 'operator=='
47
Returning from 'operator=='
48
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