mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-06 02:24:14 +08:00
bpf, x64: save one byte per shl/shr/sar when imm is 1
When we shift by one, we can use a different encoding where imm is not explicitly needed, which saves 1 byte per such op. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
parent
ee07862f7b
commit
88e69a1fcc
@ -640,7 +640,11 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image,
|
||||
case BPF_RSH: b3 = 0xE8; break;
|
||||
case BPF_ARSH: b3 = 0xF8; break;
|
||||
}
|
||||
EMIT3(0xC1, add_1reg(b3, dst_reg), imm32);
|
||||
|
||||
if (imm32 == 1)
|
||||
EMIT2(0xD1, add_1reg(b3, dst_reg));
|
||||
else
|
||||
EMIT3(0xC1, add_1reg(b3, dst_reg), imm32);
|
||||
break;
|
||||
|
||||
case BPF_ALU | BPF_LSH | BPF_X:
|
||||
|
Loading…
Reference in New Issue
Block a user