glibc/sysdeps/x86_64/multiarch/memset-evex-unaligned-erms.S
Noah Goldstein e59ced2384 x86: Optimize memset-vec-unaligned-erms.S
No bug.

Optimization are

1. change control flow for L(more_2x_vec) to fall through to loop and
   jump for L(less_4x_vec) and L(less_8x_vec). This uses less code
   size and saves jumps for length > 4x VEC_SIZE.

2. For EVEX/AVX512 move L(less_vec) closer to entry.

3. Avoid complex address mode for length > 2x VEC_SIZE

4. Slightly better aligning code for the loop from the perspective of
   code size and uops.

5. Align targets so they make full use of their fetch block and if
   possible cache line.

6. Try and reduce total number of icache lines that will need to be
   pulled in for a given length.

7. Include "local" version of stosb target. For AVX2/EVEX/AVX512
   jumping to the stosb target in the sse2 code section will almost
   certainly be to a new page. The new version does increase code size
   marginally by duplicating the target but should get better iTLB
   behavior as a result.

test-memset, test-wmemset, and test-bzero are all passing.

Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
2021-10-12 13:38:02 -05:00

32 lines
659 B
ArmAsm

#if IS_IN (libc)
# define USE_WITH_EVEX 1
# define VEC_SIZE 32
# define MOV_SIZE 6
# define RET_SIZE 1
# define XMM0 xmm16
# define YMM0 ymm16
# define VEC0 ymm16
# define VEC(i) VEC##i
# define VMOVU vmovdqu64
# define VMOVA vmovdqa64
# define VZEROUPPER
# define MEMSET_VDUP_TO_VEC0_AND_SET_RETURN(d, r) \
movq r, %rax; \
vpbroadcastb d, %VEC0
# define WMEMSET_VDUP_TO_VEC0_AND_SET_RETURN(d, r) \
movq r, %rax; \
vpbroadcastd d, %VEC0
# define SECTION(p) p##.evex
# define MEMSET_SYMBOL(p,s) p##_evex_##s
# define WMEMSET_SYMBOL(p,s) p##_evex_##s
# define USE_LESS_VEC_MASK_STORE 1
# include "memset-vec-unaligned-erms.S"
#endif