Messages in this thread | | | Date | Mon, 07 Dec 2020 13:04:23 -0800 | From | John Fastabend <> | Subject | RE: [PATCH bpf-next v4 01/11] bpf: x86: Factor out emission of ModR/M for *(reg + off) |
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Brendan Jackman wrote: > The case for JITing atomics is about to get more complicated. Let's > factor out some common code to make the review and result more > readable. > > NB the atomics code doesn't yet use the new helper - a subsequent > patch will add its use as a side-effect of other changes. > > Signed-off-by: Brendan Jackman <jackmanb@google.com> > ---
Small nit on style preference below.
Acked-by: John Fastabend <john.fastabend@gmail.com>
[...]
> > @@ -1240,11 +1250,7 @@ st: if (is_imm8(insn->off)) > goto xadd; > case BPF_STX | BPF_XADD | BPF_DW: > EMIT3(0xF0, add_2mod(0x48, dst_reg, src_reg), 0x01); > -xadd: if (is_imm8(insn->off)) > - EMIT2(add_2reg(0x40, dst_reg, src_reg), insn->off); > - else > - EMIT1_off32(add_2reg(0x80, dst_reg, src_reg), > - insn->off); > +xadd: emit_modrm_dstoff(&prog, dst_reg, src_reg, insn->off);
I at least prefer the xadd on its own line above the emit_*(). That seems more consistent with the rest of the code in this file. The only other example like this is st:.
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