[PATCH] D119652: [OpaquePtr][ValueTracking] Check GEP source element type in isPointerOffset()

[Arthur Eubanks via Phabricator via llvm-commits]

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


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D119652

Files:
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/test/Transforms/MemCpyOpt/opaque-ptr.ll


Index: llvm/test/Transforms/MemCpyOpt/opaque-ptr.ll
===================================================================
--- llvm/test/Transforms/MemCpyOpt/opaque-ptr.ll
+++ llvm/test/Transforms/MemCpyOpt/opaque-ptr.ll
@@ -22,6 +22,7 @@
 define void @test_non_const_gep(ptr %src, i64 %i) {
 ; CHECK-LABEL: @test_non_const_gep(
 ; 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)
Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -7136,7 +7136,8 @@
   // 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.


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