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[LLVM] Fix dangling access to aliasee in stripAndAccumulateConstantOf… #159214

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[LLVM] Fix dangling access to aliasee in stripAndAccumulateConstantOf… #159214

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2 changes: 1 addition & 1 deletion llvm/lib/IR/Value.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -776,7 +776,7 @@ const Value *Value::stripAndAccumulateConstantOffsets(
Operator::getOpcode(V) == Instruction::AddrSpaceCast) {
V = cast<Operator>(V)->getOperand(0);
} else if (auto *GA = dyn_cast<GlobalAlias>(V)) {
if (!GA->isInterposable())
if (!GA->isInterposable() && GA->getAliasee())
V = GA->getAliasee();
} else if (const auto *Call = dyn_cast<CallBase>(V)) {
if (const Value *RV = Call->getReturnedArgOperand())
Expand Down
31 changes: 31 additions & 0 deletions llvm/unittests/IR/InstructionsTest.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@
#include "llvm-c/Core.h"
#include "llvm/ADT/CombinationGenerator.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Analysis/TargetFolder.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Analysis/VectorUtils.h"
#include "llvm/AsmParser/Parser.h"
Expand Down Expand Up @@ -874,6 +875,36 @@ TEST(InstructionsTest, GEPIndices) {
delete GEPI;
}

TEST(InstructionsTest, PtrToIntGEPFolding) {
LLVMContext Context;
llvm::Module *M = new llvm::Module("PtrToIntGEPFolding", Context);
llvm::IRBuilder<llvm::TargetFolder> Builder(
Context, llvm::TargetFolder(M->getDataLayout()));

auto *Int64Ty = Builder.getInt64Ty();
auto *ArrTy = llvm::ArrayType::get(Int64Ty, 1);
auto *StructTy = llvm::StructType::create(Context, {ArrTy}, "anon_struct");

// Create alias @m2 to @0
llvm::GlobalAlias *AliasM2 = llvm::GlobalAlias::create(
StructTy,
0, // address space
llvm::GlobalValue::InternalLinkage, "m2", (llvm::Constant *)nullptr, M);

// Build getelementptr for ptrtoint
std::vector<llvm::Value *> GEPIdxs = {
llvm::ConstantInt::get(llvm::Type::getInt32Ty(Context), 0),
llvm::ConstantInt::get(llvm::Type::getInt32Ty(Context), 0),
llvm::ConstantInt::get(llvm::Type::getInt32Ty(Context), 1)};
llvm::Value *GEP = Builder.CreateGEP(StructTy, AliasM2, GEPIdxs, "",
llvm::GEPNoWrapFlags::inBounds());
// Make sure stripAndAccumulateConstantOffsets can properly handle
// GEPs with nullptr global aliasees.
llvm::Value *PtrToInt = Builder.CreatePtrToInt(GEP, Int64Ty);
EXPECT_TRUE(PtrToInt);
delete M;
}

TEST(InstructionsTest, ZeroIndexGEP) {
LLVMContext Context;
DataLayout DL;
Expand Down