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gsk/ngl/fp16.c: Implement runtime F16C detection on MSVC

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We need to use __cpuid() to check for the presence of F16C instructions on
Visual Studio builds, and call the half_to_float4() or float_to_half4()
implementation accordingly, as the __builtin_cpu...() functions are strictly
for GCC or CLang only.

Also, since __m128i_u is not a standard intrisics type across the board, just
use __m128i on Visual Studio as it is safe to do so there for use for
_mm_loadl_epi64().

Like running on Darwin, we cannot use the alias __attribute__ as __attribute__
is also for GCC and CLang only.
This commit is contained in:
Chun-wei Fan 2021-04-12 16:48:15 +08:00
parent 6d6c8c59eb
commit d5ced21264
1 changed files with 60 additions and 3 deletions
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63
gsk/ngl/fp16.c
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@ -80,6 +80,12 @@ half_to_float4_c (const guint16 h[4],
#ifdef HAVE_F16C
#if defined(_MSC_VER) && !defined(__clang__)
#define CAST_M128I_P(a) (__m128i const *) a
#else
#define CAST_M128I_P(a) (__m128i_u const *) a
#endif
static void
float_to_half4_f16c (const float f[4],
guint16 h[4])
@ -93,11 +99,61 @@ static void
half_to_float4_f16c (const guint16 h[4],
float f[4])
{
__m128i i = _mm_loadl_epi64 ((__m128i_u const *)h);
__m128i i = _mm_loadl_epi64 (CAST_M128I_P (h));
__m128 s = _mm_cvtph_ps (i);
_mm_store_ps (f, s);
}
#undef CAST_M128I_P
#if defined(_MSC_VER) && !defined(__clang__)
/* based on info from https://walbourn.github.io/directxmath-f16c-and-fma/ */
static gboolean
have_f16c_msvc (void)
{
static gboolean result = FALSE;
static gsize inited = 0;
if (g_once_init_enter (&inited))
{
int cpuinfo[4] = { -1 };
__cpuid (cpuinfo, 0);
if (cpuinfo[0] > 0)
{
__cpuid (cpuinfo, 1);
if ((cpuinfo[2] & 0x8000000) != 0)
result = (cpuinfo[2] & 0x20000000) != 0;
}
g_once_init_leave (&inited, 1);
}
return result;
}
void
float_to_half4 (const float f[4], guint16 h[4])
{
if (have_f16c_msvc ())
float_to_half4_f16c (f, h);
else
float_to_half4_c (f, h);
}
void
half_to_float4 (const guint16 h[4], float f[4])
{
if (have_f16c_msvc ())
half_to_float4_f16c (h, f);
else
half_to_float4_c (h, f);
}
#else
void float_to_half4 (const float f[4], guint16 h[4]) __attribute__((ifunc ("resolve_float_to_half4")));
void half_to_float4 (const guint16 h[4], float f[4]) __attribute__((ifunc ("resolve_half_to_float4")));
@ -120,11 +176,12 @@ resolve_half_to_float4 (void)
else
return half_to_float4_c;
}
#endif
#else
#ifdef __APPLE__
// turns out aliases don't work on Darwin
#if defined(__APPLE__) || (defined(_MSC_VER) && !defined(__clang__))
// turns out aliases don't work on Darwin nor Visual Studio
void
float_to_half4 (const float f[4],