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[InstCombine] Track inserted instructions when lowering objectsize

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The inserted instructions can usually be simplified. Make sure this
happens in the same InstCombine iteration by adding them to the
worklist.

We happen to get some better optimization in two cases, but this is
just a lucky accident. https://github.com/llvm/llvm-project/issues/63472
tracks implementing a fold for that case.

This doesn't track all inserted instructions yet, for that we would
also have to include those created by ObjectSizeOffsetEvaluator.
This commit is contained in:
Nikita Popov 2023-06-23 15:09:11 +02:00
parent 940c94e1c1
commit 8762f4c748
5 changed files with 31 additions and 27 deletions
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7
llvm/include/llvm/Analysis/MemoryBuiltins.h
View File

@ -182,9 +182,10 @@ bool getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout &DL,
/// argument of the call to objectsize.
Value *lowerObjectSizeCall(IntrinsicInst *ObjectSize, const DataLayout &DL,
const TargetLibraryInfo *TLI, bool MustSucceed);
Value *lowerObjectSizeCall(IntrinsicInst *ObjectSize, const DataLayout &DL,
const TargetLibraryInfo *TLI, AAResults *AA,
bool MustSucceed);
Value *lowerObjectSizeCall(
IntrinsicInst *ObjectSize, const DataLayout &DL,
const TargetLibraryInfo *TLI, AAResults *AA, bool MustSucceed,
SmallVectorImpl<Instruction *> *InsertedInstructions = nullptr);
using SizeOffsetType = std::pair<APInt, APInt>;

14
llvm/lib/Analysis/MemoryBuiltins.cpp
View File

@ -602,10 +602,10 @@ Value *llvm::lowerObjectSizeCall(IntrinsicInst *ObjectSize,
MustSucceed);
}
Value *llvm::lowerObjectSizeCall(IntrinsicInst *ObjectSize,
const DataLayout &DL,
const TargetLibraryInfo *TLI, AAResults *AA,
bool MustSucceed) {
Value *llvm::lowerObjectSizeCall(
IntrinsicInst *ObjectSize, const DataLayout &DL,
const TargetLibraryInfo *TLI, AAResults *AA, bool MustSucceed,
SmallVectorImpl<Instruction *> *InsertedInstructions) {
assert(ObjectSize->getIntrinsicID() == Intrinsic::objectsize &&
"ObjectSize must be a call to llvm.objectsize!");
@ -640,7 +640,11 @@ Value *llvm::lowerObjectSizeCall(IntrinsicInst *ObjectSize,
Eval.compute(ObjectSize->getArgOperand(0));
if (SizeOffsetPair != ObjectSizeOffsetEvaluator::unknown()) {
IRBuilder<TargetFolder> Builder(Ctx, TargetFolder(DL));
IRBuilder<TargetFolder, IRBuilderCallbackInserter> Builder(
Ctx, TargetFolder(DL), IRBuilderCallbackInserter([&](Instruction *I) {
if (InsertedInstructions)
InsertedInstructions->push_back(I);
}));
Builder.SetInsertPoint(ObjectSize);
// If we've outside the end of the object, then we can always access

10
llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
View File

@ -1488,10 +1488,16 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
Intrinsic::ID IID = II->getIntrinsicID();
switch (IID) {
case Intrinsic::objectsize:
if (Value *V = lowerObjectSizeCall(II, DL, &TLI, AA, /*MustSucceed=*/false))
case Intrinsic::objectsize: {
SmallVector<Instruction *> InsertedInstructions;
if (Value *V = lowerObjectSizeCall(II, DL, &TLI, AA, /*MustSucceed=*/false,
&InsertedInstructions)) {
for (Instruction *Inserted : InsertedInstructions)
Worklist.add(Inserted);
return replaceInstUsesWith(CI, V);
}
return nullptr;
}
case Intrinsic::abs: {
Value *IIOperand = II->getArgOperand(0);
bool IntMinIsPoison = cast<Constant>(II->getArgOperand(1))->isOneValue();

7
llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
View File

@ -2397,8 +2397,11 @@ Instruction *InstCombinerImpl::visitAllocSite(Instruction &MI) {
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
if (II->getIntrinsicID() == Intrinsic::objectsize) {
Value *Result =
lowerObjectSizeCall(II, DL, &TLI, AA, /*MustSucceed=*/true);
SmallVector<Instruction *> InsertedInstructions;
Value *Result = lowerObjectSizeCall(
II, DL, &TLI, AA, /*MustSucceed=*/true, &InsertedInstructions);
for (Instruction *Inserted : InsertedInstructions)
Worklist.add(Inserted);
replaceInstUsesWith(*I, Result);
eraseInstFromFunction(*I);
Users[i] = nullptr; // Skip examining in the next loop.

20
llvm/test/Transforms/InstCombine/builtin-dynamic-object-size.ll
View File

@ -1,5 +1,5 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
; RUN: opt -passes=instcombine -S < %s | FileCheck %s
; RUN: opt -passes=instcombine -instcombine-infinite-loop-threshold=2 -S < %s | FileCheck %s
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128-p7:32:32"
target triple = "x86_64-apple-macosx10.14.0"
@ -212,13 +212,8 @@ define i64 @as_cast(i1 %c) {
; CHECK-LABEL: define i64 @as_cast
; CHECK-SAME: (i1 [[C:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = select i1 [[C]], i64 64, i64 1
; CHECK-NEXT: [[NOT_C:%.*]] = xor i1 [[C]], true
; CHECK-NEXT: [[DOTNEG:%.*]] = sext i1 [[NOT_C]] to i64
; CHECK-NEXT: [[TMP1:%.*]] = add nsw i64 [[TMP0]], [[DOTNEG]]
; CHECK-NEXT: [[TMP2:%.*]] = icmp ne i64 [[TMP1]], -1
; CHECK-NEXT: call void @llvm.assume(i1 [[TMP2]])
; CHECK-NEXT: ret i64 [[TMP1]]
; CHECK-NEXT: [[TMP0:%.*]] = select i1 [[C]], i64 64, i64 0
; CHECK-NEXT: ret i64 [[TMP0]]
;
entry:
%p0 = tail call ptr @malloc(i64 64)
@ -233,13 +228,8 @@ define i64 @constexpr_as_cast(i1 %c) {
; CHECK-LABEL: define i64 @constexpr_as_cast
; CHECK-SAME: (i1 [[C:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = select i1 [[C]], i64 64, i64 1
; CHECK-NEXT: [[NOT_C:%.*]] = xor i1 [[C]], true
; CHECK-NEXT: [[DOTNEG:%.*]] = sext i1 [[NOT_C]] to i64
; CHECK-NEXT: [[TMP1:%.*]] = add nsw i64 [[TMP0]], [[DOTNEG]]
; CHECK-NEXT: [[TMP2:%.*]] = icmp ne i64 [[TMP1]], -1
; CHECK-NEXT: call void @llvm.assume(i1 [[TMP2]])
; CHECK-NEXT: ret i64 [[TMP1]]
; CHECK-NEXT: [[TMP0:%.*]] = select i1 [[C]], i64 64, i64 0
; CHECK-NEXT: ret i64 [[TMP0]]
;
entry:
%p0 = tail call ptr @malloc(i64 64)