In addition to float<->half functions to convert one number (#127708), add
float_to_half_array and half_to_float_array functions:
- On x64, this uses SSE2 4-wide implementation to do the conversion
(2x faster half->float, 4x faster float->half compared to scalar),
- There's also an AVX2 codepath that uses CPU hardware F16C instructions
(8-wide), to be used when/if blender codebase will start to be built
for AVX2 (today it is not yet).
- On arm64, this uses NEON VCVT instructions to do the conversion.
Use these functions in Vulkan buffer/texture conversion code. Time taken to
convert float->half texture while viewing EXR file in image space (22M
numbers to convert): 39.7ms -> 10.1ms (would be 6.9ms if building for AVX2)
Pull Request: https://projects.blender.org/blender/blender/pulls/127838
c6f5c89669