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Fix performance regression after OPTNONE changes
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The OPTNONE changes in DLTcollab#638 introduced 25% performance regression in
Cycles render engine running on Apple Silicon:

  https://projects.blender.org/blender/blender/issues/126408

The reason for this is because as per Clang documentation optnone is
incompatible with inline, so none of the functions that is marked as
optnone is inlined. The biggest bottleneck for Cycles after that
change is _mm_mul_ps.

This change makes it so _mm_mul_ps is inlined and is no longer marked
as optnone. This solves the immediate performance regression, and the
correctness is verified using the sse2neon's test suit on M2 Ultra
and M3 Max, with various optimization levels (default, -O2, -O3).

Additionally, adding -Wstrict-aliasing flag does not introduce new
warnings.
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sergeyvfx committed Aug 16, 2024
1 parent 29716df commit ab292f2
Showing 1 changed file with 1 addition and 1 deletion.
2 changes: 1 addition & 1 deletion sse2neon.h
Original file line number Diff line number Diff line change
Expand Up @@ -2187,7 +2187,7 @@ FORCE_INLINE int _mm_movemask_ps(__m128 a)
// Multiply packed single-precision (32-bit) floating-point elements in a and b,
// and store the results in dst.
// https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_mm_mul_ps
FORCE_INLINE_OPTNONE __m128 _mm_mul_ps(__m128 a, __m128 b)
FORCE_INLINE __m128 _mm_mul_ps(__m128 a, __m128 b)
{
return vreinterpretq_m128_f32(
vmulq_f32(vreinterpretq_f32_m128(a), vreinterpretq_f32_m128(b)));
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