[Beignet] [PATCH] GBE: optimize builtin atan2.

[Song, Ruiling]

Oh, I did not check them carefully, I will send a patch to fix remaining similar issues.
One more thing, for constant indexed array, llvm will do constant propagation or optimize it into register. So, I will only modify dynamically indexed arrays.

-----Original Message-----
From: Zhigang Gong [mailto:zhigang.gong at linux.intel.com] 
Sent: Tuesday, May 20, 2014 8:54 AM
To: Song, Ruiling; beignet at lists.freedesktop.org
Subject: RE: [Beignet] [PATCH] GBE: optimize builtin atan2.

Good catch. The patch LGTM, will push latter.
I just checked the ocl_stdlib.tmpl.h. There should be some other builtin function which should be refined the same way. At least, the exp() and exp10() should be optimized.
The exp() is used in luxmark's advancepath kernel. That should bring some benefit for luxmark's performance under strict conformance condition.

> -----Original Message-----
> From: Beignet [mailto:beignet-bounces at lists.freedesktop.org] On Behalf 
> Of Ruiling Song
> Sent: Monday, May 19, 2014 4:43 PM
> To: beignet at lists.freedesktop.org
> Cc: Ruiling Song
> Subject: [Beignet] [PATCH] GBE: optimize builtin atan2.
> 
> clang will generate extra stores for the implementation.
> So, put the data in __constant address space.
> This will improve opencv test PhaseFixture_Phase by 3x.
> 
> Signed-off-by: Ruiling Song <ruiling.song at intel.com>
> ---
>  backend/src/ocl_stdlib.tmpl.h |   25 +++++++++++++------------
>  1 file changed, 13 insertions(+), 12 deletions(-)
> 
> diff --git a/backend/src/ocl_stdlib.tmpl.h 
> b/backend/src/ocl_stdlib.tmpl.h
index
> cd8b918..01bb337 100755
> --- a/backend/src/ocl_stdlib.tmpl.h
> +++ b/backend/src/ocl_stdlib.tmpl.h
> @@ -2386,20 +2386,21 @@ INLINE_OVERLOADABLE float 
> __gen_ocl_internal_acos(float x) {  INLINE_OVERLOADABLE float 
> __gen_ocl_internal_acospi(float x) {
>    return __gen_ocl_internal_acos(x) / M_PI_F;  }
> +__constant float atanhi[4] = {
> +  4.6364760399e-01, /* atan(0.5)hi 0x3eed6338 */
> +  7.8539812565e-01, /* atan(1.0)hi 0x3f490fda */
> +  9.8279368877e-01, /* atan(1.5)hi 0x3f7b985e */
> +  1.5707962513e+00, /* atan(inf)hi 0x3fc90fda */ }; __constant float 
> +atanlo[4] = {
> +  5.0121582440e-09, /* atan(0.5)lo 0x31ac3769 */
> +  3.7748947079e-08, /* atan(1.0)lo 0x33222168 */
> +  3.4473217170e-08, /* atan(1.5)lo 0x33140fb4 */
> +  7.5497894159e-08, /* atan(inf)lo 0x33a22168 */ };
> +
>  INLINE_OVERLOADABLE float __gen_ocl_internal_atan(float x) {
>    /* copied from fdlibm */
> -  float atanhi[4];
> -  atanhi[0] = 4.6364760399e-01; /* atan(0.5)hi 0x3eed6338 */
> -  atanhi[1] = 7.8539812565e-01; /* atan(1.0)hi 0x3f490fda */
> -  atanhi[2] = 9.8279368877e-01; /* atan(1.5)hi 0x3f7b985e */
> -  atanhi[3] = 1.5707962513e+00; /* atan(inf)hi 0x3fc90fda */
> -
> -  float atanlo[4];
> -  atanlo[0] = 5.0121582440e-09; /* atan(0.5)lo 0x31ac3769 */
> -  atanlo[1] =  3.7748947079e-08; /* atan(1.0)lo 0x33222168 */
> -  atanlo[2] =  3.4473217170e-08; /* atan(1.5)lo 0x33140fb4 */
> -  atanlo[3] =  7.5497894159e-08; /* atan(inf)lo 0x33a22168 */
> -
>    float aT[11];
>    aT[0] = 3.3333334327e-01; /* 0x3eaaaaaa */
>    aT[1] =  -2.0000000298e-01; /* 0xbe4ccccd */
> --
> 1.7.10.4
> 
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