Bug Summary

File:src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Transforms/Utils/CallPromotionUtils.cpp
Warning:line 321, column 19
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 CallPromotionUtils.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/CallPromotionUtils.cpp
1//===- CallPromotionUtils.cpp - Utilities for call promotion ----*- 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 implements utilities useful for promoting indirect call sites to
10// direct call sites.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Transforms/Utils/CallPromotionUtils.h"
15#include "llvm/Analysis/Loads.h"
16#include "llvm/Analysis/TypeMetadataUtils.h"
17#include "llvm/IR/IRBuilder.h"
18#include "llvm/IR/Instructions.h"
19#include "llvm/Transforms/Utils/BasicBlockUtils.h"
20
21using namespace llvm;
22
23#define DEBUG_TYPE "call-promotion-utils"
24
25/// Fix-up phi nodes in an invoke instruction's normal destination.
26///
27/// After versioning an invoke instruction, values coming from the original
28/// block will now be coming from the "merge" block. For example, in the code
29/// below:
30///
31/// then_bb:
32/// %t0 = invoke i32 %ptr() to label %merge_bb unwind label %unwind_dst
33///
34/// else_bb:
35/// %t1 = invoke i32 %ptr() to label %merge_bb unwind label %unwind_dst
36///
37/// merge_bb:
38/// %t2 = phi i32 [ %t0, %then_bb ], [ %t1, %else_bb ]
39/// br %normal_dst
40///
41/// normal_dst:
42/// %t3 = phi i32 [ %x, %orig_bb ], ...
43///
44/// "orig_bb" is no longer a predecessor of "normal_dst", so the phi nodes in
45/// "normal_dst" must be fixed to refer to "merge_bb":
46///
47/// normal_dst:
48/// %t3 = phi i32 [ %x, %merge_bb ], ...
49///
50static void fixupPHINodeForNormalDest(InvokeInst *Invoke, BasicBlock *OrigBlock,
51 BasicBlock *MergeBlock) {
52 for (PHINode &Phi : Invoke->getNormalDest()->phis()) {
53 int Idx = Phi.getBasicBlockIndex(OrigBlock);
54 if (Idx == -1)
55 continue;
56 Phi.setIncomingBlock(Idx, MergeBlock);
57 }
58}
59
60/// Fix-up phi nodes in an invoke instruction's unwind destination.
61///
62/// After versioning an invoke instruction, values coming from the original
63/// block will now be coming from either the "then" block or the "else" block.
64/// For example, in the code below:
65///
66/// then_bb:
67/// %t0 = invoke i32 %ptr() to label %merge_bb unwind label %unwind_dst
68///
69/// else_bb:
70/// %t1 = invoke i32 %ptr() to label %merge_bb unwind label %unwind_dst
71///
72/// unwind_dst:
73/// %t3 = phi i32 [ %x, %orig_bb ], ...
74///
75/// "orig_bb" is no longer a predecessor of "unwind_dst", so the phi nodes in
76/// "unwind_dst" must be fixed to refer to "then_bb" and "else_bb":
77///
78/// unwind_dst:
79/// %t3 = phi i32 [ %x, %then_bb ], [ %x, %else_bb ], ...
80///
81static void fixupPHINodeForUnwindDest(InvokeInst *Invoke, BasicBlock *OrigBlock,
82 BasicBlock *ThenBlock,
83 BasicBlock *ElseBlock) {
84 for (PHINode &Phi : Invoke->getUnwindDest()->phis()) {
85 int Idx = Phi.getBasicBlockIndex(OrigBlock);
86 if (Idx == -1)
87 continue;
88 auto *V = Phi.getIncomingValue(Idx);
89 Phi.setIncomingBlock(Idx, ThenBlock);
90 Phi.addIncoming(V, ElseBlock);
91 }
92}
93
94/// Create a phi node for the returned value of a call or invoke instruction.
95///
96/// After versioning a call or invoke instruction that returns a value, we have
97/// to merge the value of the original and new instructions. We do this by
98/// creating a phi node and replacing uses of the original instruction with this
99/// phi node.
100///
101/// For example, if \p OrigInst is defined in "else_bb" and \p NewInst is
102/// defined in "then_bb", we create the following phi node:
103///
104/// ; Uses of the original instruction are replaced by uses of the phi node.
105/// %t0 = phi i32 [ %orig_inst, %else_bb ], [ %new_inst, %then_bb ],
106///
107static void createRetPHINode(Instruction *OrigInst, Instruction *NewInst,
108 BasicBlock *MergeBlock, IRBuilder<> &Builder) {
109
110 if (OrigInst->getType()->isVoidTy() || OrigInst->use_empty())
111 return;
112
113 Builder.SetInsertPoint(&MergeBlock->front());
114 PHINode *Phi = Builder.CreatePHI(OrigInst->getType(), 0);
115 SmallVector<User *, 16> UsersToUpdate(OrigInst->users());
116 for (User *U : UsersToUpdate)
117 U->replaceUsesOfWith(OrigInst, Phi);
118 Phi->addIncoming(OrigInst, OrigInst->getParent());
119 Phi->addIncoming(NewInst, NewInst->getParent());
120}
121
122/// Cast a call or invoke instruction to the given type.
123///
124/// When promoting a call site, the return type of the call site might not match
125/// that of the callee. If this is the case, we have to cast the returned value
126/// to the correct type. The location of the cast depends on if we have a call
127/// or invoke instruction.
128///
129/// For example, if the call instruction below requires a bitcast after
130/// promotion:
131///
132/// orig_bb:
133/// %t0 = call i32 @func()
134/// ...
135///
136/// The bitcast is placed after the call instruction:
137///
138/// orig_bb:
139/// ; Uses of the original return value are replaced by uses of the bitcast.
140/// %t0 = call i32 @func()
141/// %t1 = bitcast i32 %t0 to ...
142/// ...
143///
144/// A similar transformation is performed for invoke instructions. However,
145/// since invokes are terminating, a new block is created for the bitcast. For
146/// example, if the invoke instruction below requires a bitcast after promotion:
147///
148/// orig_bb:
149/// %t0 = invoke i32 @func() to label %normal_dst unwind label %unwind_dst
150///
151/// The edge between the original block and the invoke's normal destination is
152/// split, and the bitcast is placed there:
153///
154/// orig_bb:
155/// %t0 = invoke i32 @func() to label %split_bb unwind label %unwind_dst
156///
157/// split_bb:
158/// ; Uses of the original return value are replaced by uses of the bitcast.
159/// %t1 = bitcast i32 %t0 to ...
160/// br label %normal_dst
161///
162static void createRetBitCast(CallBase &CB, Type *RetTy, CastInst **RetBitCast) {
163
164 // Save the users of the calling instruction. These uses will be changed to
165 // use the bitcast after we create it.
166 SmallVector<User *, 16> UsersToUpdate(CB.users());
167
168 // Determine an appropriate location to create the bitcast for the return
169 // value. The location depends on if we have a call or invoke instruction.
170 Instruction *InsertBefore = nullptr;
171 if (auto *Invoke = dyn_cast<InvokeInst>(&CB))
172 InsertBefore =
173 &SplitEdge(Invoke->getParent(), Invoke->getNormalDest())->front();
174 else
175 InsertBefore = &*std::next(CB.getIterator());
176
177 // Bitcast the return value to the correct type.
178 auto *Cast = CastInst::CreateBitOrPointerCast(&CB, RetTy, "", InsertBefore);
179 if (RetBitCast)
180 *RetBitCast = Cast;
181
182 // Replace all the original uses of the calling instruction with the bitcast.
183 for (User *U : UsersToUpdate)
184 U->replaceUsesOfWith(&CB, Cast);
185}
186
187/// Predicate and clone the given call site.
188///
189/// This function creates an if-then-else structure at the location of the call
190/// site. The "if" condition compares the call site's called value to the given
191/// callee. The original call site is moved into the "else" block, and a clone
192/// of the call site is placed in the "then" block. The cloned instruction is
193/// returned.
194///
195/// For example, the call instruction below:
196///
197/// orig_bb:
198/// %t0 = call i32 %ptr()
199/// ...
200///
201/// Is replace by the following:
202///
203/// orig_bb:
204/// %cond = icmp eq i32 ()* %ptr, @func
205/// br i1 %cond, %then_bb, %else_bb
206///
207/// then_bb:
208/// ; The clone of the original call instruction is placed in the "then"
209/// ; block. It is not yet promoted.
210/// %t1 = call i32 %ptr()
211/// br merge_bb
212///
213/// else_bb:
214/// ; The original call instruction is moved to the "else" block.
215/// %t0 = call i32 %ptr()
216/// br merge_bb
217///
218/// merge_bb:
219/// ; Uses of the original call instruction are replaced by uses of the phi
220/// ; node.
221/// %t2 = phi i32 [ %t0, %else_bb ], [ %t1, %then_bb ]
222/// ...
223///
224/// A similar transformation is performed for invoke instructions. However,
225/// since invokes are terminating, more work is required. For example, the
226/// invoke instruction below:
227///
228/// orig_bb:
229/// %t0 = invoke %ptr() to label %normal_dst unwind label %unwind_dst
230///
231/// Is replace by the following:
232///
233/// orig_bb:
234/// %cond = icmp eq i32 ()* %ptr, @func
235/// br i1 %cond, %then_bb, %else_bb
236///
237/// then_bb:
238/// ; The clone of the original invoke instruction is placed in the "then"
239/// ; block, and its normal destination is set to the "merge" block. It is
240/// ; not yet promoted.
241/// %t1 = invoke i32 %ptr() to label %merge_bb unwind label %unwind_dst
242///
243/// else_bb:
244/// ; The original invoke instruction is moved into the "else" block, and
245/// ; its normal destination is set to the "merge" block.
246/// %t0 = invoke i32 %ptr() to label %merge_bb unwind label %unwind_dst
247///
248/// merge_bb:
249/// ; Uses of the original invoke instruction are replaced by uses of the
250/// ; phi node, and the merge block branches to the normal destination.
251/// %t2 = phi i32 [ %t0, %else_bb ], [ %t1, %then_bb ]
252/// br %normal_dst
253///
254/// An indirect musttail call is processed slightly differently in that:
255/// 1. No merge block needed for the orginal and the cloned callsite, since
256/// either one ends the flow. No phi node is needed either.
257/// 2. The return statement following the original call site is duplicated too
258/// and placed immediately after the cloned call site per the IR convention.
259///
260/// For example, the musttail call instruction below:
261///
262/// orig_bb:
263/// %t0 = musttail call i32 %ptr()
264/// ...
265///
266/// Is replaced by the following:
267///
268/// cond_bb:
269/// %cond = icmp eq i32 ()* %ptr, @func
270/// br i1 %cond, %then_bb, %orig_bb
271///
272/// then_bb:
273/// ; The clone of the original call instruction is placed in the "then"
274/// ; block. It is not yet promoted.
275/// %t1 = musttail call i32 %ptr()
276/// ret %t1
277///
278/// orig_bb:
279/// ; The original call instruction stays in its original block.
280/// %t0 = musttail call i32 %ptr()
281/// ret %t0
282static CallBase &versionCallSite(CallBase &CB, Value *Callee,
283 MDNode *BranchWeights) {
284
285 IRBuilder<> Builder(&CB);
286 CallBase *OrigInst = &CB;
287 BasicBlock *OrigBlock = OrigInst->getParent();
288
289 // Create the compare. The called value and callee must have the same type to
290 // be compared.
291 if (CB.getCalledOperand()->getType() != Callee->getType())
2
←
Assuming the condition is false
→
3
←
Taking false branch
→
292 Callee = Builder.CreateBitCast(Callee, CB.getCalledOperand()->getType());
293 auto *Cond = Builder.CreateICmpEQ(CB.getCalledOperand(), Callee);
294
295 if (OrigInst->isMustTailCall()) {
4
←
Assuming the condition is true
→
5
←
Taking true branch
→
296 // Create an if-then structure. The original instruction stays in its block,
297 // and a clone of the original instruction is placed in the "then" block.
298 Instruction *ThenTerm =
299 SplitBlockAndInsertIfThen(Cond, &CB, false, BranchWeights);
300 BasicBlock *ThenBlock = ThenTerm->getParent();
301 ThenBlock->setName("if.true.direct_targ");
302 CallBase *NewInst = cast<CallBase>(OrigInst->clone());
6
←
The object is a 'CallBase'
→
303 NewInst->insertBefore(ThenTerm);
304
305 // Place a clone of the optional bitcast after the new call site.
306 Value *NewRetVal = NewInst;
307 auto Next = OrigInst->getNextNode();
308 if (auto *BitCast
7.1
'BitCast' is null
 = dyn_cast_or_null<BitCastInst>(Next)) {
7
←
Assuming null pointer is passed into cast
→
8
←
Taking false branch
→
309 assert(BitCast->getOperand(0) == OrigInst &&((void)0)
310 "bitcast following musttail call must use the call")((void)0);
311 auto NewBitCast = BitCast->clone();
312 NewBitCast->replaceUsesOfWith(OrigInst, NewInst);
313 NewBitCast->insertBefore(ThenTerm);
314 NewRetVal = NewBitCast;
315 Next = BitCast->getNextNode();
316 }
317
318 // Place a clone of the return instruction after the new call site.
319 ReturnInst *Ret = dyn_cast_or_null<ReturnInst>(Next);
9
←
Assuming null pointer is passed into cast
→
10
←
'Ret' initialized to a null pointer value
→
320 assert(Ret && "musttail call must precede a ret with an optional bitcast")((void)0);
321 auto NewRet = Ret->clone();
11
←
Called C++ object pointer is null
322 if (Ret->getReturnValue())
323 NewRet->replaceUsesOfWith(Ret->getReturnValue(), NewRetVal);
324 NewRet->insertBefore(ThenTerm);
325
326 // A return instructions is terminating, so we don't need the terminator
327 // instruction just created.
328 ThenTerm->eraseFromParent();
329
330 return *NewInst;
331 }
332
333 // Create an if-then-else structure. The original instruction is moved into
334 // the "else" block, and a clone of the original instruction is placed in the
335 // "then" block.
336 Instruction *ThenTerm = nullptr;
337 Instruction *ElseTerm = nullptr;
338 SplitBlockAndInsertIfThenElse(Cond, &CB, &ThenTerm, &ElseTerm, BranchWeights);
339 BasicBlock *ThenBlock = ThenTerm->getParent();
340 BasicBlock *ElseBlock = ElseTerm->getParent();
341 BasicBlock *MergeBlock = OrigInst->getParent();
342
343 ThenBlock->setName("if.true.direct_targ");
344 ElseBlock->setName("if.false.orig_indirect");
345 MergeBlock->setName("if.end.icp");
346
347 CallBase *NewInst = cast<CallBase>(OrigInst->clone());
348 OrigInst->moveBefore(ElseTerm);
349 NewInst->insertBefore(ThenTerm);
350
351 // If the original call site is an invoke instruction, we have extra work to
352 // do since invoke instructions are terminating. We have to fix-up phi nodes
353 // in the invoke's normal and unwind destinations.
354 if (auto *OrigInvoke = dyn_cast<InvokeInst>(OrigInst)) {
355 auto *NewInvoke = cast<InvokeInst>(NewInst);
356
357 // Invoke instructions are terminating, so we don't need the terminator
358 // instructions that were just created.
359 ThenTerm->eraseFromParent();
360 ElseTerm->eraseFromParent();
361
362 // Branch from the "merge" block to the original normal destination.
363 Builder.SetInsertPoint(MergeBlock);
364 Builder.CreateBr(OrigInvoke->getNormalDest());
365
366 // Fix-up phi nodes in the original invoke's normal and unwind destinations.
367 fixupPHINodeForNormalDest(OrigInvoke, OrigBlock, MergeBlock);
368 fixupPHINodeForUnwindDest(OrigInvoke, MergeBlock, ThenBlock, ElseBlock);
369
370 // Now set the normal destinations of the invoke instructions to be the
371 // "merge" block.
372 OrigInvoke->setNormalDest(MergeBlock);
373 NewInvoke->setNormalDest(MergeBlock);
374 }
375
376 // Create a phi node for the returned value of the call site.
377 createRetPHINode(OrigInst, NewInst, MergeBlock, Builder);
378
379 return *NewInst;
380}
381
382bool llvm::isLegalToPromote(const CallBase &CB, Function *Callee,
383 const char **FailureReason) {
384 assert(!CB.getCalledFunction() && "Only indirect call sites can be promoted")((void)0);
385
386 auto &DL = Callee->getParent()->getDataLayout();
387
388 // Check the return type. The callee's return value type must be bitcast
389 // compatible with the call site's type.
390 Type *CallRetTy = CB.getType();
391 Type *FuncRetTy = Callee->getReturnType();
392 if (CallRetTy != FuncRetTy)
393 if (!CastInst::isBitOrNoopPointerCastable(FuncRetTy, CallRetTy, DL)) {
394 if (FailureReason)
395 *FailureReason = "Return type mismatch";
396 return false;
397 }
398
399 // The number of formal arguments of the callee.
400 unsigned NumParams = Callee->getFunctionType()->getNumParams();
401
402 // The number of actual arguments in the call.
403 unsigned NumArgs = CB.arg_size();
404
405 // Check the number of arguments. The callee and call site must agree on the
406 // number of arguments.
407 if (NumArgs != NumParams && !Callee->isVarArg()) {
408 if (FailureReason)
409 *FailureReason = "The number of arguments mismatch";
410 return false;
411 }
412
413 // Check the argument types. The callee's formal argument types must be
414 // bitcast compatible with the corresponding actual argument types of the call
415 // site.
416 unsigned I = 0;
417 for (; I < NumParams; ++I) {
418 Type *FormalTy = Callee->getFunctionType()->getFunctionParamType(I);
419 Type *ActualTy = CB.getArgOperand(I)->getType();
420 if (FormalTy == ActualTy)
421 continue;
422 if (!CastInst::isBitOrNoopPointerCastable(ActualTy, FormalTy, DL)) {
423 if (FailureReason)
424 *FailureReason = "Argument type mismatch";
425 return false;
426 }
427 }
428 for (; I < NumArgs; I++) {
429 // Vararg functions can have more arguments than parameters.
430 assert(Callee->isVarArg())((void)0);
431 if (CB.paramHasAttr(I, Attribute::StructRet)) {
432 if (FailureReason)
433 *FailureReason = "SRet arg to vararg function";
434 return false;
435 }
436 }
437
438 return true;
439}
440
441CallBase &llvm::promoteCall(CallBase &CB, Function *Callee,
442 CastInst **RetBitCast) {
443 assert(!CB.getCalledFunction() && "Only indirect call sites can be promoted")((void)0);
444
445 // Set the called function of the call site to be the given callee (but don't
446 // change the type).
447 CB.setCalledOperand(Callee);
448
449 // Since the call site will no longer be direct, we must clear metadata that
450 // is only appropriate for indirect calls. This includes !prof and !callees
451 // metadata.
452 CB.setMetadata(LLVMContext::MD_prof, nullptr);
453 CB.setMetadata(LLVMContext::MD_callees, nullptr);
454
455 // If the function type of the call site matches that of the callee, no
456 // additional work is required.
457 if (CB.getFunctionType() == Callee->getFunctionType())
458 return CB;
459
460 // Save the return types of the call site and callee.
461 Type *CallSiteRetTy = CB.getType();
462 Type *CalleeRetTy = Callee->getReturnType();
463
464 // Change the function type of the call site the match that of the callee.
465 CB.mutateFunctionType(Callee->getFunctionType());
466
467 // Inspect the arguments of the call site. If an argument's type doesn't
468 // match the corresponding formal argument's type in the callee, bitcast it
469 // to the correct type.
470 auto CalleeType = Callee->getFunctionType();
471 auto CalleeParamNum = CalleeType->getNumParams();
472
473 LLVMContext &Ctx = Callee->getContext();
474 const AttributeList &CallerPAL = CB.getAttributes();
475 // The new list of argument attributes.
476 SmallVector<AttributeSet, 4> NewArgAttrs;
477 bool AttributeChanged = false;
478
479 for (unsigned ArgNo = 0; ArgNo < CalleeParamNum; ++ArgNo) {
480 auto *Arg = CB.getArgOperand(ArgNo);
481 Type *FormalTy = CalleeType->getParamType(ArgNo);
482 Type *ActualTy = Arg->getType();
483 if (FormalTy != ActualTy) {
484 auto *Cast = CastInst::CreateBitOrPointerCast(Arg, FormalTy, "", &CB);
485 CB.setArgOperand(ArgNo, Cast);
486
487 // Remove any incompatible attributes for the argument.
488 AttrBuilder ArgAttrs(CallerPAL.getParamAttributes(ArgNo));
489 ArgAttrs.remove(AttributeFuncs::typeIncompatible(FormalTy));
490
491 // If byval is used, this must be a pointer type, and the byval type must
492 // match the element type. Update it if present.
493 if (ArgAttrs.getByValType())
494 ArgAttrs.addByValAttr(Callee->getParamByValType(ArgNo));
495
496 NewArgAttrs.push_back(AttributeSet::get(Ctx, ArgAttrs));
497 AttributeChanged = true;
498 } else
499 NewArgAttrs.push_back(CallerPAL.getParamAttributes(ArgNo));
500 }
501
502 // If the return type of the call site doesn't match that of the callee, cast
503 // the returned value to the appropriate type.
504 // Remove any incompatible return value attribute.
505 AttrBuilder RAttrs(CallerPAL, AttributeList::ReturnIndex);
506 if (!CallSiteRetTy->isVoidTy() && CallSiteRetTy != CalleeRetTy) {
507 createRetBitCast(CB, CallSiteRetTy, RetBitCast);
508 RAttrs.remove(AttributeFuncs::typeIncompatible(CalleeRetTy));
509 AttributeChanged = true;
510 }
511
512 // Set the new callsite attribute.
513 if (AttributeChanged)
514 CB.setAttributes(AttributeList::get(Ctx, CallerPAL.getFnAttributes(),
515 AttributeSet::get(Ctx, RAttrs),
516 NewArgAttrs));
517
518 return CB;
519}
520
521CallBase &llvm::promoteCallWithIfThenElse(CallBase &CB, Function *Callee,
522 MDNode *BranchWeights) {
523
524 // Version the indirect call site. If the called value is equal to the given
525 // callee, 'NewInst' will be executed, otherwise the original call site will
526 // be executed.
527 CallBase &NewInst = versionCallSite(CB, Callee, BranchWeights);
1
Calling 'versionCallSite'
→
528
529 // Promote 'NewInst' so that it directly calls the desired function.
530 return promoteCall(NewInst, Callee);
531}
532
533bool llvm::tryPromoteCall(CallBase &CB) {
534 assert(!CB.getCalledFunction())((void)0);
535 Module *M = CB.getCaller()->getParent();
536 const DataLayout &DL = M->getDataLayout();
537 Value *Callee = CB.getCalledOperand();
538
539 LoadInst *VTableEntryLoad = dyn_cast<LoadInst>(Callee);
540 if (!VTableEntryLoad)
541 return false; // Not a vtable entry load.
542 Value *VTableEntryPtr = VTableEntryLoad->getPointerOperand();
543 APInt VTableOffset(DL.getTypeSizeInBits(VTableEntryPtr->getType()), 0);
544 Value *VTableBasePtr = VTableEntryPtr->stripAndAccumulateConstantOffsets(
545 DL, VTableOffset, /* AllowNonInbounds */ true);
546 LoadInst *VTablePtrLoad = dyn_cast<LoadInst>(VTableBasePtr);
547 if (!VTablePtrLoad)
548 return false; // Not a vtable load.
549 Value *Object = VTablePtrLoad->getPointerOperand();
550 APInt ObjectOffset(DL.getTypeSizeInBits(Object->getType()), 0);
551 Value *ObjectBase = Object->stripAndAccumulateConstantOffsets(
552 DL, ObjectOffset, /* AllowNonInbounds */ true);
553 if (!(isa<AllocaInst>(ObjectBase) && ObjectOffset == 0))
554 // Not an Alloca or the offset isn't zero.
555 return false;
556
557 // Look for the vtable pointer store into the object by the ctor.
558 BasicBlock::iterator BBI(VTablePtrLoad);
559 Value *VTablePtr = FindAvailableLoadedValue(
560 VTablePtrLoad, VTablePtrLoad->getParent(), BBI, 0, nullptr, nullptr);
561 if (!VTablePtr)
562 return false; // No vtable found.
563 APInt VTableOffsetGVBase(DL.getTypeSizeInBits(VTablePtr->getType()), 0);
564 Value *VTableGVBase = VTablePtr->stripAndAccumulateConstantOffsets(
565 DL, VTableOffsetGVBase, /* AllowNonInbounds */ true);
566 GlobalVariable *GV = dyn_cast<GlobalVariable>(VTableGVBase);
567 if (!(GV && GV->isConstant() && GV->hasDefinitiveInitializer()))
568 // Not in the form of a global constant variable with an initializer.
569 return false;
570
571 Constant *VTableGVInitializer = GV->getInitializer();
572 APInt VTableGVOffset = VTableOffsetGVBase + VTableOffset;
573 if (!(VTableGVOffset.getActiveBits() <= 64))
574 return false; // Out of range.
575 Constant *Ptr = getPointerAtOffset(VTableGVInitializer,
576 VTableGVOffset.getZExtValue(),
577 *M);
578 if (!Ptr)
579 return false; // No constant (function) pointer found.
580 Function *DirectCallee = dyn_cast<Function>(Ptr->stripPointerCasts());
581 if (!DirectCallee)
582 return false; // No function pointer found.
583
584 if (!isLegalToPromote(CB, DirectCallee))
585 return false;
586
587 // Success.
588 promoteCall(CB, DirectCallee);
589 return true;
590}
591
592#undef DEBUG_TYPE