[Mesa-dev] [PATCH 3/3] util: Use SSE rounding on all platforms that support it.

[Matt Turner]

On Sun, Aug 9, 2015 at 3:57 AM, Jose Fonseca <jfonseca at vmware.com> wrote:
> As currently only GCC x86_64 builds where using it.
> ---
>  src/util/rounding.h | 16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/src/util/rounding.h b/src/util/rounding.h
> index ec31b47..38c1c2f 100644
> --- a/src/util/rounding.h
> +++ b/src/util/rounding.h
> @@ -27,7 +27,17 @@
>  #include <math.h>
>  #include <limits.h>
>
> -#ifdef __x86_64__
> +/* SSE2 is supported on: all x86_64 targets, on x86 targets when -msse2 is
> + * passed to GCC, and should also be enabled on all Windows builds. */
> +#if defined(__x86_64__) /* gcc */ || \
> +    defined(_M_X64) /* msvc */ || \
> +    defined(_M_AMD64) /* msvc */ || \
> +    defined(__SSE2__) /* gcc -msse2 */ || \

I don't think we should include __SSE2__ in this. On x86-32,
floating-point operations will be using the x87 FPU, so using SSE
intrinsics will force some transfers to and from memory.

> +    defined(_WIN32)
> +#define HAVE_SSE2 1

Does MSVC define __amd64, __amd64__, or __x86_64? The AMD64 ABI
document says these, and __x86_64__ should be defined if compiling on
x86-64. With the removal of __SSE2__ above, I'd make this

#ifndef __x86_64__
#if defined(_M_X64) /* msvc */ || \
    defined(_M_AMD64) /* msvc */ || \
    defined(_WIN32)
#define __x86_64__
#endif
#endif

> +#endif
> +
> +#ifdef HAVE_SSE2
>  #include <xmmintrin.h>
>  #include <emmintrin.h>
>  #endif
> @@ -93,7 +103,7 @@ _mesa_roundeven(double x)
>  static inline long
>  _mesa_lroundevenf(float x)
>  {
> -#ifdef __x86_64__
> +#ifdef HAVE_SSE2
>  #if LONG_BIT == 64
>     return _mm_cvtss_si64(_mm_load_ss(&x));
>  #elif LONG_BIT == 32 || defined(_WIN32)
> @@ -113,7 +123,7 @@ _mesa_lroundevenf(float x)
>  static inline long
>  _mesa_lroundeven(double x)
>  {
> -#ifdef __x86_64__
> +#ifdef HAVE_SSE2
>  #if LONG_BIT == 64
>     return _mm_cvtsd_si64(_mm_load_sd(&x));
>  #elif LONG_BIT == 32 || defined(_WIN32)
> --
> 2.1.4
>