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[OpaquePtr][ValueTracking] Check GEP source element type in isPointerOffset() 

Fixes a MemCpyOpt miscompile with opaque pointers.
This function can be further cleaned up, but let's just fix the miscompile first.

Reviewed By: #opaque-pointers, nikic

Differential Revision: https://reviews.llvm.org/D119652
This commit is contained in:
Arthur Eubanks 2022-02-12 17:37:20 -08:00
parent d5f7ae7bfe
commit a9029a33ff
2 changed files with 3 additions and 1 deletions
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3
llvm/lib/Analysis/ValueTracking.cpp
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@ -7136,7 +7136,8 @@ Optional<int64_t> llvm::isPointerOffset(const Value *Ptr1, const Value *Ptr2,
// potentially variable) indices. After that they handle some constant
// offset, which determines their offset from each other. At this point, we
// handle no other case.
if (!GEP1 || !GEP2 || GEP1->getOperand(0) != GEP2->getOperand(0))
if (!GEP1 || !GEP2 || GEP1->getOperand(0) != GEP2->getOperand(0) ||
GEP1->getSourceElementType() != GEP2->getSourceElementType())
return None;
// Skip any common indices and track the GEP types.

1
llvm/test/Transforms/MemCpyOpt/opaque-ptr.ll
View File

@ -22,6 +22,7 @@ define void @test_memset_memcpy(ptr %src, i64 %src_size, ptr noalias %dst, i64 %
define void @test_different_gep_source_elements(ptr %src) {
; CHECK-LABEL: @test_different_gep_source_elements(
; CHECK-NEXT: [[PB:%.*]] = getelementptr [[B:%.*]], ptr [[SRC:%.*]], i64 0, i32 1
; CHECK-NEXT: store i64 0, ptr [[PB]], align 4
; CHECK-NEXT: [[PA:%.*]] = getelementptr [[A:%.*]], ptr [[SRC]], i64 0, i32 1
; CHECK-NEXT: [[PA2:%.*]] = getelementptr [[A]], ptr [[SRC]], i64 0, i32 2
; CHECK-NEXT: call void @llvm.memset.p0.i64(ptr align 4 [[PA]], i8 0, i64 16, i1 false)