Ammar Faizi 12108aa8c1 tools/nolibc: x86-64: Use rep stosb for memset() ... Simplify memset() on the x86-64 arch. The x86-64 arch has a 'rep stosb' instruction, which can perform memset() using only a single instruction, given: %al = value (just like the second argument of memset()) %rdi = destination %rcx = length Before this patch: ``` 00000000000010c9 <memset>: 10c9: 48 89 f8 mov %rdi,%rax 10cc: 48 85 d2 test %rdx,%rdx 10cf: 74 0e je 10df <memset+0x16> 10d1: 31 c9 xor %ecx,%ecx 10d3: 40 88 34 08 mov %sil,(%rax,%rcx,1) 10d7: 48 ff c1 inc %rcx 10da: 48 39 ca cmp %rcx,%rdx 10dd: 75 f4 jne 10d3 <memset+0xa> 10df: c3 ret ``` After this patch: ``` 0000000000001511 <memset>: 1511: 96 xchg %eax,%esi 1512: 48 89 d1 mov %rdx,%rcx 1515: 57 push %rdi 1516: f3 aa rep stos %al,%es:(%rdi) 1518: 58 pop %rax 1519: c3 ret ``` v2: - Use pushq %rdi / popq %rax (Alviro). - Use xchg %eax, %esi (Willy). Link: https://lore.kernel.org/lkml/ZO9e6h2jjVIMpBJP@1wt.eu Suggested-by: Alviro Iskandar Setiawan <alviro.iskandar@gnuweeb.org> Suggested-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org> Reviewed-by: Alviro Iskandar Setiawan <alviro.iskandar@gnuweeb.org> Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>		2023-10-12 21:14:00 +02:00
..
asm	tools headers: Update the copy of x86's mem{cpy,set}_64.S used in 'perf bench'	2023-05-17 10:42:19 -03:00
asm-generic	tools: KVM: selftests: Convert clear/set_bit() to actual atomics	2022-12-02 13:22:35 -05:00
linux	tools include: Add some common function attributes	2023-08-04 17:36:52 +01:00
nolibc	tools/nolibc: x86-64: Use rep stosb for memset()	2023-10-12 21:14:00 +02:00
tools	tools include: add dis-asm-compat.h to handle version differences	2022-08-01 15:29:49 -03:00
trace/events
uapi	bpf: Add pid filter support for uprobe_multi link	2023-08-21 15:51:25 -07:00
vdso	tools headers: Synchronize {linux,vdso}/bits.h with the kernel sources	2023-03-03 22:34:15 -03:00