[ConstantFold] Disallow folding vector geps into bitcasts

Summary:
Getelementptr returns a vector of pointers, instead of a single address,
when one or more of its arguments is a vector. In such case it is not
possible to simplify the expression by inserting a bitcast of operand(0)
into the destination type, as it will create a bitcast between different
sizes.

Reviewers: majnemer, mkuper, mssimpso, spatel

Reviewed By: spatel

Subscribers: lebedev.ri, llvm-commits

Differential Revision: https://reviews.llvm.org/D46379

llvm-svn: 333783

1 files changed, 5 insertions, 1 deletions

diff --git a/llvm/lib/IR/ConstantFold.cpp b/llvm/lib/IR/ConstantFold.cpp
index 2404ce4..218adb4 100644
--- a/llvm/lib/IR/ConstantFold.cpp
+++ b/llvm/lib/IR/ConstantFold.cpp
@@ -545,7 +545,11 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V,
                opc != Instruction::AddrSpaceCast &&
                // Do not fold bitcast (gep) with inrange index, as this loses
                // information.
-               !cast<GEPOperator>(CE)->getInRangeIndex().hasValue()) {
+               !cast<GEPOperator>(CE)->getInRangeIndex().hasValue() &&
+               // Do not fold if the gep type is a vector, as bitcasting
+               // operand 0 of a vector gep will result in a bitcast between
+               // different sizes.
+               !CE->getType()->isVectorTy()) {
       // If all of the indexes in the GEP are null values, there is no pointer
       // adjustment going on.  We might as well cast the source pointer.
       bool isAllNull = true;