[SCEV] Take global variable linkage into account when comparing values #148071
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Current the comparator is inconsistent when we have two external globals and one internal globals due to
```
if (IsGVNameSemantic(LGV) && IsGVNameSemantic(RGV))
return LGV->getName().compare(RGV->getName());
```
The internal global compares equal to (not strictly less than) the external globals, but the external globals are not equal.
Fixes llvm#147862.
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@llvm/pr-subscribers-llvm-analysis Author: Arthur Eubanks (aeubanks) ChangesCurrent the comparator is inconsistent when we have two external globals and one internal globals due to The internal global compares equal to (not strictly less than) the external globals, but the external globals are not equal. Fixes #147862. Full diff: https://github.com/llvm/llvm-project/pull/148071.diff 2 Files Affected:
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 1c66f5c877f59..24adfa346c642 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -601,6 +601,9 @@ static int CompareValueComplexity(const LoopInfo *const LI, Value *LV,
if (const auto *LGV = dyn_cast<GlobalValue>(LV)) {
const auto *RGV = cast<GlobalValue>(RV);
+ if (auto L = LGV->getLinkage() - RGV->getLinkage())
+ return L;
+
const auto IsGVNameSemantic = [&](const GlobalValue *GV) {
auto LT = GV->getLinkage();
return !(GlobalValue::isPrivateLinkage(LT) ||
diff --git a/llvm/unittests/Analysis/ScalarEvolutionTest.cpp b/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
index 9b88e423e802b..6d6bef5477f95 100644
--- a/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
+++ b/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
@@ -1738,4 +1738,31 @@ TEST_F(ScalarEvolutionsTest, ComplexityComparatorIsStrictWeakOrdering2) {
SE.getAddExpr(Ops);
}
+TEST_F(ScalarEvolutionsTest, ComplexityComparatorIsStrictWeakOrdering3) {
+ Type *Int64Ty = Type::getInt64Ty(Context);
+ Constant *Init = Constant::getNullValue(Int64Ty);
+ Type *PtrTy = PointerType::get(Context, 0);
+ Constant *Null = Constant::getNullValue(PtrTy);
+ FunctionType *FTy = FunctionType::get(Type::getVoidTy(Context), {}, false);
+
+ Value *V0 = new GlobalVariable(M, Int64Ty, false,
+ GlobalValue::ExternalLinkage, Init, "V0");
+ Value *V1 = new GlobalVariable(M, Int64Ty, false,
+ GlobalValue::ExternalLinkage, Init, "V1");
+ Value *V2 = new GlobalVariable(M, Int64Ty, false,
+ GlobalValue::InternalLinkage, Init, "V2");
+ Function *F = Function::Create(FTy, Function::ExternalLinkage, "f", M);
+ BasicBlock *BB = BasicBlock::Create(Context, "entry", F);
+ Value *C0 = ICmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_EQ, V0, Null, "c0", BB);
+ Value *C1 = ICmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_EQ, V1, Null, "c1", BB);
+ Value *C2 = ICmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_EQ, V2, Null, "c2", BB);
+ Value*Or0 = BinaryOperator::CreateOr(C0, C1, "or0", BB);
+ Value*Or1 = BinaryOperator::CreateOr(Or0, C2, "or1", BB);
+ ReturnInst::Create(Context, nullptr, BB);
+ ScalarEvolution SE = buildSE(*F);
+ // When _LIBCPP_HARDENING_MODE == _LIBCPP_HARDENING_MODE_DEBUG, this will
+ // crash if the comparator is inconsistent about global variable linkage.
+ SE.getSCEV(Or1);
+}
+
} // end namespace llvm
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You can test this locally with the following command:git-clang-format --diff HEAD~1 HEAD --extensions cpp -- llvm/lib/Analysis/ScalarEvolution.cpp llvm/unittests/Analysis/ScalarEvolutionTest.cppView the diff from clang-format here.diff --git a/llvm/unittests/Analysis/ScalarEvolutionTest.cpp b/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
index 6d6bef547..678960418 100644
--- a/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
+++ b/llvm/unittests/Analysis/ScalarEvolutionTest.cpp
@@ -1753,11 +1753,14 @@ TEST_F(ScalarEvolutionsTest, ComplexityComparatorIsStrictWeakOrdering3) {
GlobalValue::InternalLinkage, Init, "V2");
Function *F = Function::Create(FTy, Function::ExternalLinkage, "f", M);
BasicBlock *BB = BasicBlock::Create(Context, "entry", F);
- Value *C0 = ICmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_EQ, V0, Null, "c0", BB);
- Value *C1 = ICmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_EQ, V1, Null, "c1", BB);
- Value *C2 = ICmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_EQ, V2, Null, "c2", BB);
- Value*Or0 = BinaryOperator::CreateOr(C0, C1, "or0", BB);
- Value*Or1 = BinaryOperator::CreateOr(Or0, C2, "or1", BB);
+ Value *C0 = ICmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_EQ, V0, Null,
+ "c0", BB);
+ Value *C1 = ICmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_EQ, V1, Null,
+ "c1", BB);
+ Value *C2 = ICmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_EQ, V2, Null,
+ "c2", BB);
+ Value *Or0 = BinaryOperator::CreateOr(C0, C1, "or0", BB);
+ Value *Or1 = BinaryOperator::CreateOr(Or0, C2, "or1", BB);
ReturnInst::Create(Context, nullptr, BB);
ScalarEvolution SE = buildSE(*F);
// When _LIBCPP_HARDENING_MODE == _LIBCPP_HARDENING_MODE_DEBUG, this will
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Current the comparator is inconsistent when we have two external globals and one internal globals due to
The internal global compares equal to (not strictly less than) the external globals, but the external globals are not equal.
Fixes #147862.