[PATCH] D120004: [SCEVExpander][OpaquePtr] Check GEP source type when finding identical GEP

[Arthur Eubanks via Phabricator via llvm-commits]

aeubanks created this revision.
aeubanks added a reviewer: opaque-pointers.
Herald added a subscriber: hiraditya.
aeubanks requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

Fixes an opaque pointers miscompile.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D120004

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


Index: llvm/test/Transforms/IndVarSimplify/opaque-ptr.ll
===================================================================
--- llvm/test/Transforms/IndVarSimplify/opaque-ptr.ll
+++ llvm/test/Transforms/IndVarSimplify/opaque-ptr.ll
@@ -8,12 +8,13 @@
 ; 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
Index: llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
===================================================================
--- llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
+++ llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
@@ -591,7 +591,9 @@
         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;
       }


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