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.
* (1 << w) are changed into ((uint32_t)1 << w)
* int are changed into uint32_t
gf.c: gf_composite_get_default_poly:
a larger unsigned were assigned to unsigned integers in which case
the type of the assigned variable is changed to be the same as the
value assigned to it.
gf_w16.c: GF_MULTBY_TWO
setting the parameter to a variable instead of passing the expression
resolves the warning for some reason.
Signed-off-by: Loic Dachary <loic@dachary.org>
Optimisations for the 4,4 split table region multiplication and carry
less multiplication using NEON's polynomial long multiplication.
arm: w8: NEON carry less multiplication
Selected time_tool.sh results for a 1.7GHz cortex-a9:
Region Best (MB/s): 375.86 W-Method: 8 -m CARRY_FREE -
Region Best (MB/s): 142.94 W-Method: 8 -m TABLE -
Region Best (MB/s): 225.01 W-Method: 8 -m TABLE -r DOUBLE -
Region Best (MB/s): 211.23 W-Method: 8 -m TABLE -r DOUBLE -r LAZY -
Region Best (MB/s): 160.09 W-Method: 8 -m LOG -
Region Best (MB/s): 123.61 W-Method: 8 -m LOG_ZERO -
Region Best (MB/s): 123.85 W-Method: 8 -m LOG_ZERO_EXT -
Region Best (MB/s): 1183.79 W-Method: 8 -m SPLIT 8 4 -r SIMD -
Region Best (MB/s): 177.68 W-Method: 8 -m SPLIT 8 4 -r NOSIMD -
Region Best (MB/s): 87.85 W-Method: 8 -m COMPOSITE 2 - -
Region Best (MB/s): 428.59 W-Method: 8 -m COMPOSITE 2 - -r ALTMAP -
Optimisations for the single table region multiplication and carry less
multiplication using NEON's polynomial multiplication of 8-bit values.
The single polynomial multiplication is not that useful but vector
version is for region multiplication.
Selected time_tool.sh results for a 1.7GHz cortex-a9:
Region Best (MB/s): 672.72 W-Method: 4 -m CARRY_FREE -
Region Best (MB/s): 265.84 W-Method: 4 -m BYTWO_p -
Region Best (MB/s): 329.41 W-Method: 4 -m TABLE -r DOUBLE -
Region Best (MB/s): 278.63 W-Method: 4 -m TABLE -r QUAD -
Region Best (MB/s): 329.81 W-Method: 4 -m TABLE -r QUAD -r LAZY -
Region Best (MB/s): 1318.03 W-Method: 4 -m TABLE -r SIMD -
Region Best (MB/s): 165.15 W-Method: 4 -m TABLE -r NOSIMD -
Region Best (MB/s): 99.73 W-Method: 4 -m LOG -
Bassam Tabbara