[Libclc-dev] [PATCH 2/2] math: Add tan implementation

[Matt Arsenault]

On Sep 5, 2014, at 1:57 PM, Jan Vesely <jan.vesely at rutgers.edu> wrote:

> On Thu, 2014-09-04 at 12:35 -0500, Aaron Watry wrote:
>> Uses the algorithm:
>> tan(x) = sin(x) / sqrt(1-sin^2(x))
>> 
>> An alternative is:
>> tan(x) = sin(x) / cos(x)
>> 
>> Which produces more verbose bitcode and longer assembly.
> 
> this is weird. both EG and SI have both sin and cos instructions. Is the
> input normalization code so bad that we are better of doing MUL+SUB+SQRT
> instead?

Those are only useful for native_sin / native_cos. For the standard function, they are far from precise enough. The current (float) sin implementation should be correct, though native_sin right now is still defined to just be the regular sin function instead of the LLVM intrinsic


> 
>> 
>> Either way, the generated bitcode seems pretty nasty and a more optimized
>> but still precise-enough solution is welcome.
>> 
>> Signed-off-by: Aaron Watry <awatry at gmail.com>
>> ---
>> generic/include/clc/clc.h        | 1 +
>> generic/include/clc/math/tan.h   | 2 ++
>> generic/include/clc/math/tan.inc | 1 +
>> generic/lib/SOURCES              | 1 +
>> generic/lib/math/tan.cl          | 8 ++++++++
>> generic/lib/math/tan.inc         | 8 ++++++++
>> 6 files changed, 21 insertions(+)
>> create mode 100644 generic/include/clc/math/tan.h
>> create mode 100644 generic/include/clc/math/tan.inc
>> create mode 100644 generic/lib/math/tan.cl
>> create mode 100644 generic/lib/math/tan.inc
>> 
>> diff --git a/generic/include/clc/clc.h b/generic/include/clc/clc.h
>> index 079c674..69e44b6 100644
>> --- a/generic/include/clc/clc.h
>> +++ b/generic/include/clc/clc.h
>> @@ -60,6 +60,7 @@
>> #include <clc/math/sin.h>
>> #include <clc/math/sincos.h>
>> #include <clc/math/sqrt.h>
>> +#include <clc/math/tan.h>
>> #include <clc/math/trunc.h>
>> #include <clc/math/native_cos.h>
>> #include <clc/math/native_divide.h>
>> diff --git a/generic/include/clc/math/tan.h b/generic/include/clc/math/tan.h
>> new file mode 100644
>> index 0000000..d2d52a9
>> --- /dev/null
>> +++ b/generic/include/clc/math/tan.h
>> @@ -0,0 +1,2 @@
>> +#define __CLC_BODY <clc/math/tan.inc>
>> +#include <clc/math/gentype.inc>
>> diff --git a/generic/include/clc/math/tan.inc b/generic/include/clc/math/tan.inc
>> new file mode 100644
>> index 0000000..50c5b1d
>> --- /dev/null
>> +++ b/generic/include/clc/math/tan.inc
>> @@ -0,0 +1 @@
>> +_CLC_OVERLOAD _CLC_DECL __CLC_GENTYPE tan(__CLC_GENTYPE x);
>> diff --git a/generic/lib/SOURCES b/generic/lib/SOURCES
>> index 30e182f..0667d14 100644
>> --- a/generic/lib/SOURCES
>> +++ b/generic/lib/SOURCES
>> @@ -48,6 +48,7 @@ math/pown.cl
>> math/sin.cl
>> math/sincos.cl
>> math/sincos_helpers.cl
>> +math/tan.cl
>> relational/all.cl
>> relational/any.cl
>> relational/isequal.cl
>> diff --git a/generic/lib/math/tan.cl b/generic/lib/math/tan.cl
>> new file mode 100644
>> index 0000000..a447999
>> --- /dev/null
>> +++ b/generic/lib/math/tan.cl
>> @@ -0,0 +1,8 @@
>> +#include <clc/clc.h>
>> +
>> +#ifdef cl_khr_fp64
>> +#pragma OPENCL EXTENSION cl_khr_fp64 : enable
>> +#endif
>> +
>> +#define __CLC_BODY <tan.inc>
>> +#include <clc/math/gentype.inc>
>> diff --git a/generic/lib/math/tan.inc b/generic/lib/math/tan.inc
>> new file mode 100644
>> index 0000000..8d9d9fe
>> --- /dev/null
>> +++ b/generic/lib/math/tan.inc
>> @@ -0,0 +1,8 @@
>> +/*
>> + * Note: tan(x) = sin(x)/cos(x) also, but the final assembly ends up being
>> + *       twice as long for R600 (maybe for others as well).
>> + */
>> +_CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE tan(__CLC_GENTYPE x) {
>> +  __CLC_GENTYPE sinx = sin(x);
>> +  return sinx / sqrt( (__CLC_GENTYPE) 1.0 - (sinx*sinx) );
>> +}
> 
> -- 
> Jan Vesely <jan.vesely at rutgers.edu>
> _______________________________________________
> Libclc-dev mailing list
> Libclc-dev at pcc.me.uk
> http://www.pcc.me.uk/cgi-bin/mailman/listinfo/libclc-dev

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