[Beignet] [PATCH] Set the loop unroll's threshold to 1024.

[Song, Ruiling]

Selecting a reasonable threshold seems a difficult job. I am ok with 1024.
LGTM.

> -----Original Message-----
> From: Beignet [mailto:beignet-bounces at lists.freedesktop.org] On Behalf Of
> Yang Rong
> Sent: Wednesday, July 01, 2015 11:31 AM
> To: beignet at lists.freedesktop.org
> Cc: Yang, Rong R
> Subject: [Beignet] [PATCH] Set the loop unroll's threshold to 1024.
> 
> LLVM's default threshold is 150, too small. In general, the loop unroll in GEN
> can improve the perfomance, so enlarge it to 1024.
> 
> Signed-off-by: Yang Rong <rong.r.yang at intel.com>
> ---
>  backend/src/llvm/llvm_to_gen.cpp | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/backend/src/llvm/llvm_to_gen.cpp
> b/backend/src/llvm/llvm_to_gen.cpp
> index e0f6bf2..891f2a1 100644
> --- a/backend/src/llvm/llvm_to_gen.cpp
> +++ b/backend/src/llvm/llvm_to_gen.cpp
> @@ -160,7 +160,7 @@ namespace gbe
>      MPM.add(createIndVarSimplifyPass());        // Canonicalize
> indvars
>      MPM.add(createLoopIdiomPass());             // Recognize idioms
> like memset.
>      MPM.add(createLoopDeletionPass());          // Delete dead loops
> -    MPM.add(createLoopUnrollPass()); //1024, 32, 1024, 512)); //Unroll
> loops
> +    MPM.add(createLoopUnrollPass(1024)); //1024, 32, 1024, 512));
> + //Unroll loops
>      if(optLevel > 0) {
>        MPM.add(createSROAPass(/*RequiresDomTree*/ false));
>        MPM.add(createGVNPass());                 // Remove
> redundancies
> --
> 1.8.3.2
> 
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