InstCombine should not fold sext/zext of a vector and a bitcast to a scalar to a sext/zext

llvm-svn: 94280

llvm/lib/VMCore/Instructions.cpp

@@ -2079,8 +2079,9 @@ unsigned CastInst::isEliminableCastPair(
       return secondOp;
     case 3: 
       // no-op cast in second op implies firstOp as long as the DestTy 
-      // is integer
-      if (DstTy->isInteger())
+      // is integer and we are not converting between a vector and a
+      // non vector type
+      if (SrcTy->getTypeID() != Type::VectorTyID && DstTy->isInteger())
         return firstOp;
       return 0;
     case 4:

llvm/test/Transforms/InstCombine/bitcast-sext-vector.ll

@@ -0,0 +1,11 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+; CHECK: sext
+; Don't fold zero/sign extensions with a bitcast between a vector and scalar.
+
+define i32 @t(<4 x i8> %src1, <4 x i8> %src2) nounwind readonly {
+entry:
+	%cmp = icmp eq <4 x i8> %src1, %src2; <<4 x i1>> [#uses=1]
+	%sext = sext <4 x i1> %cmp to <4 x i8>
+	%val = bitcast <4 x i8> %sext to i32
+	ret i32 %val
+}