[Beignet] [PATCH] GBE: don't try to erase a llvm:Constant.

[Ruiling Song]

If it is a llvm::Constant, don't add it to erase candidate.
The reason I make this change is it cannot cast to llvm::Instruction.
I think we still need to make clear whether or not we should
delete a constant and how.

Signed-off-by: Ruiling Song <ruiling.song at intel.com>
---
 backend/src/llvm/ExpandLargeIntegers.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/backend/src/llvm/ExpandLargeIntegers.cpp b/backend/src/llvm/ExpandLargeIntegers.cpp
index 00987cb..e466665 100644
--- a/backend/src/llvm/ExpandLargeIntegers.cpp
+++ b/backend/src/llvm/ExpandLargeIntegers.cpp
@@ -324,12 +324,14 @@ static Value *buildVectorOrScalar(ConversionState &State, IRBuilder<> &IRB, Smal
     Value * vec = NULL;
     unsigned ElemNo = Elements.size();
     Type *ElemTy = Elements[0]->getType();
+    // if it is illegal integer type, these instructions will be further
+    // splited, that's why these temporary values should be erased.
     bool KeepInsert = isLegalBitSize(ElemTy->getPrimitiveSizeInBits() * ElemNo);
     for (unsigned i = 0; i < ElemNo; ++i) {
       Value *tmp = vec ? vec : UndefValue::get(VectorType::get(ElemTy, ElemNo));
       Value *idx = ConstantInt::get(IntTy, i);
       vec = IRB.CreateInsertElement(tmp, Elements[i], idx);
-      if (!KeepInsert) {
+      if (!KeepInsert && !isa<Constant>(vec)) {
         State.addEraseCandidate(cast<Instruction>(vec));
       }
     }
-- 
2.4.1