This commits adds support for runtime detection of SIMD instructions. The idea is that you would build once with all supported SIMD functions and the same binaries could run on different machines with varying support for SIMD. At runtime gf-complete will select the right functions based on the processor.
gf_cpu.c has the logic to detect SIMD instructions. On Intel processors this is done through cpuid. For ARM on linux we use getauxv.
The logic in gf_w*.c has been changed to check for runtime SIMD support and fallback to generic code.
Also a new test has been added. It compares the functions selected by gf_init when we enable/disable SIMD support through build flags, with runtime enabling/disabling. The test checks if the results are identical.
This commit adds a couple of scripts that help test SIMD functionality
on different machines through QEMU.
tools/test_simd_qemu.sh will automatically start qemu, run tests
and stop it. it uses the Ubuntu cloud images which are built for
x86_64, arm and arm64.
tools/test_simd.sh run a number of tests including compiling
with different flags, unit tests, and gathering the functions
selected in gf_init (and when compiling with DEBUG_FUNCTIONS)
Bassam Tabbara