math: Add acos implementation

Passes the tests that were submitted to the piglit list

Tested on R600 (Pitcairn)

Signed-off-by: Aaron Watry <awatry@gmail.com>
Reviewed-by: Jan Vesely <jan.vesely@rutgers.edu>
llvm-svn: 217509
This commit is contained in:
Aaron Watry 2014-09-10 15:43:29 +00:00
parent 3826224428
commit 268beab921
6 changed files with 34 additions and 0 deletions

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@ -32,6 +32,7 @@
#include <clc/workitem/get_group_id.h>
/* 6.11.2 Math Functions */
#include <clc/math/acos.h>
#include <clc/math/atan.h>
#include <clc/math/atan2.h>
#include <clc/math/copysign.h>

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@ -0,0 +1,2 @@
#define __CLC_BODY <clc/math/acos.inc>
#include <clc/math/gentype.inc>

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@ -0,0 +1 @@
_CLC_OVERLOAD _CLC_DECL __CLC_GENTYPE acos(__CLC_GENTYPE x);

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@ -29,6 +29,7 @@ integer/sub_sat.cl
integer/sub_sat_if.ll
integer/sub_sat_impl.ll
integer/upsample.cl
math/acos.cl
math/atan.cl
math/atan2.cl
math/copysign.cl

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@ -0,0 +1,8 @@
#include <clc/clc.h>
#ifdef cl_khr_fp64
#pragma OPENCL EXTENSION cl_khr_fp64 : enable
#endif
#define __CLC_BODY <acos.inc>
#include <clc/math/gentype.inc>

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@ -0,0 +1,21 @@
/*
* There are multiple formulas for calculating arccosine of x:
* 1) acos(x) = (1/2*pi) + i * ln(i*x + sqrt(1-x^2)) (notice the 'i'...)
* 2) acos(x) = pi/2 + asin(-x) (asin isn't implemented yet)
* 3) acos(x) = pi/2 - asin(x) (ditto)
* 4) acos(x) = 2*atan2(sqrt(1-x), sqrt(1+x))
* 5) acos(x) = pi/2 - atan2(x, ( sqrt(1-x^2) ) )
*
* Options 1-3 are not currently usable, #5 generates more concise radeonsi
* bitcode and assembly than #4 (134 vs 132 instructions on radeonsi), but
* precision of #4 may be better.
*/
_CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE acos(__CLC_GENTYPE x) {
return (
(__CLC_GENTYPE) 2.0 * atan2(
sqrt((__CLC_GENTYPE) 1.0 - x),
sqrt((__CLC_GENTYPE) 1.0 + x)
)
);
}