[PATCH] D100970: [Evaluator] Bitcast result of pointer stripping

[Arthur Eubanks via Phabricator via llvm-commits]

aeubanks created this revision.
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Trying to evaluate a GEP would assert with

  "Ty == cast<PointerType>(C->getType()->getScalarType())->getElementType()"

because the type of the pointer we would evaluate the GEP argument to
would be a different type than the GEP was expecting. We should treat
pointer stripping as a bitcast.

The test adds a redundant GEP that would crash due to type mismatch.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D100970

Files:
  llvm/lib/Transforms/Utils/Evaluator.cpp
  llvm/test/Transforms/GlobalOpt/invariant.group.ll


Index: llvm/test/Transforms/GlobalOpt/invariant.group.ll
===================================================================
--- llvm/test/Transforms/GlobalOpt/invariant.group.ll
+++ llvm/test/Transforms/GlobalOpt/invariant.group.ll
@@ -32,9 +32,10 @@
 
   %0 = bitcast i32* %valptr to i8*
   %barr = call i8* @llvm.launder.invariant.group(i8* %0)
-  %1 = bitcast i8* %barr to i32*
+  %1 = getelementptr i8, i8* %barr, i32 0
+  %2 = bitcast i8* %1 to i32*
 
-  %val2 = load i32, i32* %1
+  %val2 = load i32, i32* %2
   store i32 %val2, i32* @tmp2
   ret void
 }
Index: llvm/lib/Transforms/Utils/Evaluator.cpp
===================================================================
--- llvm/lib/Transforms/Utils/Evaluator.cpp
+++ llvm/lib/Transforms/Utils/Evaluator.cpp
@@ -566,6 +566,7 @@
                        << "Stripped pointer casts for alias analysis for "
                           "intrinsic call.\n");
             StrippedPointerCastsForAliasAnalysis = true;
+            InstResult = ConstantExpr::getBitCast(InstResult, II->getType());
           } else {
             LLVM_DEBUG(dbgs() << "Unknown intrinsic. Cannot evaluate.\n");
             return false;


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