Where can I find a reference for the AMD FMA 4 intrinsics?

StackOverflow https://stackoverflow.com/questions/10033562

Question

I am trying to modify a piece of code that uses SSE (128bit) calls to use the 256bit FMA feature on the Bulldozer Opteron. I cant seem to find the intrinsics for these calls.

Some questions on this forum have used these intrinsics (ex: How to find the horizontal maximum in a 256-bit AVX vector )

I found this: http://msdn.microsoft.com/en-us/library/gg445140.aspx
and http://software.intel.com/sites/products/documentation/studio/composer/en-us/2011/compiler_c/index.htm#intref_cls/common/intref_avx_fmadd_ps.htm

But I cant seem to find anything on AMD developer docs.

Was it helpful?

Solution

You find the intrinsics in the file fma4intrin.h. Here are the 256 bit instructions from this file, some function attributes stripped. The __buitin* functions emit the FMA instruction which is part of their name. So if you want to find a intrinsic function name, you need to lookup the correct __builtin_instructionname after the return and use the surrounding function wrapper.

/* 256b Floating point multiply/add type instructions.  */
_mm256_macc_ps (__m256 __A, __m256 __B, __m256 __C)
{
  return (__m256) __builtin_ia32_vfmaddps256 ((__v8sf)__A, (__v8sf)__B, (__v8sf)__C);
}

_mm256_macc_pd (__m256d __A, __m256d __B, __m256d __C)
{
  return (__m256d) __builtin_ia32_vfmaddpd256 ((__v4df)__A, (__v4df)__B, (__v4df)__C);
}

_mm256_msub_ps (__m256 __A, __m256 __B, __m256 __C)
{
  return (__m256) __builtin_ia32_vfmaddps256 ((__v8sf)__A, (__v8sf)__B, -(__v8sf)__C);
}

_mm256_msub_pd (__m256d __A, __m256d __B, __m256d __C)
{
  return (__m256d) __builtin_ia32_vfmaddpd256 ((__v4df)__A, (__v4df)__B, -(__v4df)__C);
}

_mm256_nmacc_ps (__m256 __A, __m256 __B, __m256 __C)
{
  return (__m256) __builtin_ia32_vfmaddps256 (-(__v8sf)__A, (__v8sf)__B, (__v8sf)__C);
}

_mm256_nmacc_pd (__m256d __A, __m256d __B, __m256d __C)
{
  return (__m256d) __builtin_ia32_vfmaddpd256 (-(__v4df)__A, (__v4df)__B, (__v4df)__C);
}

_mm256_nmsub_ps (__m256 __A, __m256 __B, __m256 __C)
{
  return (__m256) __builtin_ia32_vfmaddps256 (-(__v8sf)__A, (__v8sf)__B, -(__v8sf)__C);
}

_mm256_nmsub_pd (__m256d __A, __m256d __B, __m256d __C)
{
  return (__m256d) __builtin_ia32_vfmaddpd256 (-(__v4df)__A, (__v4df)__B, -(__v4df)__C);
}

_mm256_maddsub_ps (__m256 __A, __m256 __B, __m256 __C)
{
  return (__m256) __builtin_ia32_vfmaddsubps256 ((__v8sf)__A, (__v8sf)__B, (__v8sf)__C);
}

_mm256_maddsub_pd (__m256d __A, __m256d __B, __m256d __C)
{
  return (__m256d) __builtin_ia32_vfmaddsubpd256 ((__v4df)__A, (__v4df)__B, (__v4df)__C);
}

_mm256_msubadd_ps (__m256 __A, __m256 __B, __m256 __C)
{
  return (__m256) __builtin_ia32_vfmaddsubps256 ((__v8sf)__A, (__v8sf)__B, -(__v8sf)__C);
}

_mm256_msubadd_pd (__m256d __A, __m256d __B, __m256d __C)
{
  return (__m256d) __builtin_ia32_vfmaddsubpd256 ((__v4df)__A, (__v4df)__B, -(__v4df)__C);
}

OTHER TIPS

You probably need this document http://support.amd.com/TechDocs/43479.pdf. It contains all XOP and FMA4 intrinsics

Just for completion - for the Microsoft version of the header above, use:

#include <immintrin.h>
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