Patch for a new instcombine xform, patch contributed by Nick Lewycky!

This implements Transforms/InstCombine/2006-05-10-InvalidIndexUndef.ll

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28450 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp
index a848e7461eb3f87f55578fe2ddfa16c2ab73f08f..3998923dd1ac46986f794e07180ba148646db8a0 100644 (file)
--- a/lib/Transforms/Utils/Local.cpp
+++ b/lib/Transforms/Utils/Local.cpp
@@ -273,7 +273,8 @@ Constant *llvm::ConstantFoldLoadThroughGEPConstantExpr(Constant *C,
       }
     } else if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) {
       if (const ArrayType *ATy = dyn_cast<ArrayType>(*I)) {
-        if ((uint64_t)CI->getRawValue() >= ATy->getNumElements()) return 0;
+        if ((uint64_t)CI->getRawValue() >= ATy->getNumElements())
+          C = UndefValue::get(ATy->getElementType());
         if (ConstantArray *CA = dyn_cast<ConstantArray>(C))
           C = CA->getOperand((unsigned)CI->getRawValue());
         else if (isa<ConstantAggregateZero>(C))
@@ -283,7 +284,8 @@ Constant *llvm::ConstantFoldLoadThroughGEPConstantExpr(Constant *C,
         else
           return 0;
       } else if (const PackedType *PTy = dyn_cast<PackedType>(*I)) {
-        if ((uint64_t)CI->getRawValue() >= PTy->getNumElements()) return 0;
+        if ((uint64_t)CI->getRawValue() >= PTy->getNumElements())
+          C = UndefValue::get(PTy->getElementType());
         if (ConstantPacked *CP = dyn_cast<ConstantPacked>(C))
           C = CP->getOperand((unsigned)CI->getRawValue());
         else if (isa<ConstantAggregateZero>(C))