[Beignet] [PATCH v2 2/2] GBE: optimize GEP constant offset calculation.

[Song, Ruiling]

LGTM, the code becomes cleaner.

> -----Original Message-----
> From: Beignet [mailto:beignet-bounces at lists.freedesktop.org] On Behalf Of
> Zhigang Gong
> Sent: Tuesday, December 02, 2014 2:43 PM
> To: beignet at lists.freedesktop.org
> Cc: Gong, Zhigang
> Subject: [Beignet] [PATCH v2 2/2] GBE: optimize GEP constant offset
> calculation.
> 
> If the type is array or vector, we do not need to iterate each element.
> We can compute it directly.
> 
> v2:
> Use more generic SequentialType and StructType to identify whether we can
> compute the offset directly.
> 
> Signed-off-by: Zhigang Gong <zhigang.gong at intel.com>
> ---
>  backend/src/llvm/llvm_passes.cpp | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/backend/src/llvm/llvm_passes.cpp
> b/backend/src/llvm/llvm_passes.cpp
> index 24ad9d0..ff9ab76 100644
> --- a/backend/src/llvm/llvm_passes.cpp
> +++ b/backend/src/llvm/llvm_passes.cpp
> @@ -275,7 +275,7 @@ namespace gbe
>      Value* currentAddrInst =
>        new PtrToIntInst(parentPointer,
> IntegerType::get(GEPInst->getContext(), ptrSize), "", GEPInst);
> 
> -    uint32_t constantOffset = 0;
> +    int32_t constantOffset = 0;
> 
>      for(uint32_t op=1; op<GEPInst->getNumOperands(); ++op)
>      {
> @@ -286,15 +286,17 @@ namespace gbe
>          int32_t offset = 0;
>          TypeIndex = ConstOP->getZExtValue();
>          int32_t step = TypeIndex > 0 ? 1 : -1;
> -        if (op == 1) {
> +        SequentialType * seqType = dyn_cast<SequentialType>(CompTy);
> +        if (seqType != NULL) {
>            if (TypeIndex != 0) {
> -            Type *elementType =
> (cast<PointerType>(parentPointer->getType()))->getElementType();
> +            Type *elementType = seqType->getElementType();
>              uint32_t elementSize = getTypeByteSize(unit, elementType);
>              uint32_t align = getAlignmentByte(unit, elementType);
>              elementSize += getPadding(elementSize, align);
>              offset += elementSize * TypeIndex;
>            }
>          } else {
> +          GBE_ASSERT(CompTy->isStructTy());
>            for(int32_t ty_i=0; ty_i != TypeIndex; ty_i += step)
>            {
>              Type* elementType = CompTy->getTypeAtIndex(ty_i);
> --
> 1.8.3.2
> 
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