Jie Meng 57a610f1c5 bpf, x64: Save bytes for DIV by reducing reg copies ... Instead of unconditionally performing push/pop on %rax/%rdx in case of division/modulo, we can save a few bytes in case of destination register being either BPF r0 (%rax) or r3 (%rdx) since the result is written in there anyway. Also, we do not need to copy the source to %r11 unless the source is either %rax, %rdx or an immediate. For example, before the patch: 22: push %rax 23: push %rdx 24: mov %rsi,%r11 27: xor %edx,%edx 29: div %r11 2c: mov %rax,%r11 2f: pop %rdx 30: pop %rax 31: mov %r11,%rax After: 22: push %rdx 23: xor %edx,%edx 25: div %rsi 28: pop %rdx Signed-off-by: Jie Meng <jmeng@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Tested-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20211002035626.2041910-1-jmeng@fb.com		2021-10-06 15:24:36 +02:00
..
bpf_jit_comp32.c	bpf: Introduce BPF nospec instruction for mitigating Spectre v4	2021-07-29 00:20:56 +02:00
bpf_jit_comp.c	bpf, x64: Save bytes for DIV by reducing reg copies	2021-10-06 15:24:36 +02:00
Makefile	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00