[llvm] 129af4d - [SCEVExpander][OpaquePtr] Check GEP source type when finding identical GEP

[Arthur Eubanks via llvm-commits]

Author: Arthur Eubanks
Date: 2022-02-17T08:48:11-08:00
New Revision: 129af4daa7ce6ca8d1d649de4eba76129c199399

URL: https://github.com/llvm/llvm-project/commit/129af4daa7ce6ca8d1d649de4eba76129c199399
DIFF: https://github.com/llvm/llvm-project/commit/129af4daa7ce6ca8d1d649de4eba76129c199399.diff

LOG: [SCEVExpander][OpaquePtr] Check GEP source type when finding identical GEP

Fixes an opaque pointers miscompile.

Reviewed By: #opaque-pointers, nikic

Differential Revision: https://reviews.llvm.org/D120004

Added: 
    

Modified: 
    llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
    llvm/test/Transforms/IndVarSimplify/opaque-ptr.ll

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp b/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
index 007578d9ada7..754382aa0845 100644
--- a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
+++ b/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
@@ -591,7 +591,9 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin,
         if (isa<DbgInfoIntrinsic>(IP))
           ScanLimit++;
         if (IP->getOpcode() == Instruction::GetElementPtr &&
-            IP->getOperand(0) == V && IP->getOperand(1) == Idx)
+            IP->getOperand(0) == V && IP->getOperand(1) == Idx &&
+            cast<GEPOperator>(&*IP)->getSourceElementType() ==
+                Type::getInt8Ty(Ty->getContext()))
           return &*IP;
         if (IP == BlockBegin) break;
       }

diff  --git a/llvm/test/Transforms/IndVarSimplify/opaque-ptr.ll b/llvm/test/Transforms/IndVarSimplify/opaque-ptr.ll
index c6af7014ef53..3b36930b68ba 100644
--- a/llvm/test/Transforms/IndVarSimplify/opaque-ptr.ll
+++ b/llvm/test/Transforms/IndVarSimplify/opaque-ptr.ll
@@ -8,12 +8,13 @@ define void @test(ptr %arg) {
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[O:%.*]] = getelementptr ptr, ptr [[ARG:%.*]], i64 16
 ; CHECK-NEXT:    call void @c(ptr [[O]])
+; CHECK-NEXT:    [[UGLYGEP:%.*]] = getelementptr i8, ptr [[ARG]], i64 16
 ; CHECK-NEXT:    br label [[LOOP:%.*]]
 ; CHECK:       loop:
 ; CHECK-NEXT:    [[IDX:%.*]] = phi i32 [ 1, [[ENTRY:%.*]] ], [ [[INC:%.*]], [[LOOP]] ]
 ; CHECK-NEXT:    [[INC]] = add nuw nsw i32 [[IDX]], 1
 ; CHECK-NEXT:    [[C:%.*]] = icmp ne i32 [[INC]], 16
-; CHECK-NEXT:    call void @c(ptr [[O]])
+; CHECK-NEXT:    call void @c(ptr [[UGLYGEP]])
 ; CHECK-NEXT:    br i1 [[C]], label [[LOOP]], label [[END:%.*]]
 ; CHECK:       end:
 ; CHECK-NEXT:    ret void