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Cycles: Use native float->half conversion instructions for Haswell CPUs. 

This makes OCIO viewport color correction a little bit faster (about -0.5s for 100 samples)
Also set max half float value to 65504.0 to conform with IEEE 754.
This commit is contained in:
Sv. Lockal 2015-05-10 16:20:04 +00:00
parent 3a2c0ccdd0
commit 2ec221aa28
2 changed files with 16 additions and 18 deletions
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4
intern/cycles/CMakeLists.txt
View File

@ -64,7 +64,7 @@ elseif(CMAKE_COMPILER_IS_GNUCC)
set(CYCLES_AVX_KERNEL_FLAGS "-ffast-math -msse -msse2 -msse3 -mssse3 -msse4.1 -mavx -mfpmath=sse")
endif()
if(CXX_HAS_AVX2)
set(CYCLES_AVX2_KERNEL_FLAGS "-ffast-math -msse -msse2 -msse3 -mssse3 -msse4.1 -mavx -mavx2 -mfma -mlzcnt -mbmi -mbmi2 -mfpmath=sse")
set(CYCLES_AVX2_KERNEL_FLAGS "-ffast-math -msse -msse2 -msse3 -mssse3 -msse4.1 -mavx -mavx2 -mfma -mlzcnt -mbmi -mbmi2 -mf16c -mfpmath=sse")
endif()
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -ffast-math")
elseif(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
@ -80,7 +80,7 @@ elseif(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
set(CYCLES_AVX_KERNEL_FLAGS "-ffast-math -msse -msse2 -msse3 -mssse3 -msse4.1 -mavx")
endif()
if(CXX_HAS_AVX2)
set(CYCLES_AVX2_KERNEL_FLAGS "-ffast-math -msse -msse2 -msse3 -mssse3 -msse4.1 -mavx -mavx2 -mfma -mlzcnt -mbmi -mbmi2")
set(CYCLES_AVX2_KERNEL_FLAGS "-ffast-math -msse -msse2 -msse3 -mssse3 -msse4.1 -mavx -mavx2 -mfma -mlzcnt -mbmi -mbmi2 -mf16c")
endif()
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -ffast-math")
endif()

30
intern/cycles/util/util_half.h
View File

@ -54,12 +54,10 @@ ccl_device_inline void float4_store_half(half *h, float4 f, float scale)
for(int i = 0; i < 4; i++) {
/* optimized float to half for pixels:
* assumes no negative, no nan, no inf, and sets denormal to 0 */
union { uint i; float f; } in;
float fscale = f[i] * scale;
in.f = (fscale > 0.0f)? ((fscale < 65500.0f)? fscale: 65500.0f): 0.0f;
int x = in.i;
float x = min(max(fscale, 0.0f), 65504.0f);
int absolute = x & 0x7FFFFFFF;
int absolute = __float_as_uint(in) & 0x7FFFFFFF;
int Z = absolute + 0xC8000000;
int result = (absolute < 0x38800000)? 0: Z;
int rshift = (result >> 13);
@ -68,20 +66,20 @@ ccl_device_inline void float4_store_half(half *h, float4 f, float scale)
}
#else
/* same as above with SSE */
const ssef mm_scale = ssef(scale);
const ssei mm_38800000 = ssei(0x38800000);
const ssei mm_7FFF = ssei(0x7FFF);
const ssei mm_7FFFFFFF = ssei(0x7FFFFFFF);
const ssei mm_C8000000 = ssei(0xC8000000);
ssef fscale = load4f(f) * scale;
ssef x = min(max(fscale, 0.0f), 65504.0f);
ssef mm_fscale = load4f(f) * mm_scale;
ssei x = cast(min(max(mm_fscale, ssef(0.0f)), ssef(65500.0f)));
ssei absolute = x & mm_7FFFFFFF;
ssei Z = absolute + mm_C8000000;
ssei result = andnot(absolute < mm_38800000, Z);
ssei rh = (result >> 13) & mm_7FFF;
#ifdef __KERNEL_AVX2__
ssei rpack = _mm_cvtps_ph(x, 0);
#else
ssei absolute = cast(x) & 0x7FFFFFFF;
ssei Z = absolute + 0xC8000000;
ssei result = andnot(absolute < 0x38800000, Z);
ssei rshift = (result >> 13) & 0x7FFF;
ssei rpack = _mm_packs_epi32(rshift, rshift);
#endif
_mm_storel_pi((__m64*)h, _mm_castsi128_ps(_mm_packs_epi32(rh, rh)));
_mm_storel_pi((__m64*)h, _mm_castsi128_ps(rpack));
#endif
}