Messages in this thread | | | Date | Wed, 26 Nov 2014 09:23:59 -0800 | Subject | Re: [PATCH] x86: bpf_jit_comp: simplify trivial boolean return | From | Alexei Starovoitov <> |
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On Wed, Nov 26, 2014 at 8:58 AM, Joe Perches <joe@perches.com> wrote: > On Wed, 2014-11-26 at 08:42 -0800, Alexei Starovoitov wrote: >> On Wed, Nov 26, 2014 at 1:18 AM, Quentin Lambert >> <lambert.quentin@gmail.com> wrote: >> > Remove if then else statements preceding >> > boolean return. > [] >> > diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c > [] >> > @@ -135,11 +135,9 @@ static const int reg2hex[] = { >> > */ >> > static inline bool is_ereg(u32 reg) >> > { >> > - if (reg == BPF_REG_5 || reg == AUX_REG || >> > - (reg >= BPF_REG_7 && reg <= BPF_REG_9)) >> > - return true; >> > - else >> > - return false; >> > + return (reg == BPF_REG_5 || >> > + reg == AUX_REG || >> > + (reg >= BPF_REG_7 && reg <= BPF_REG_9)); >> >> please remove extra () around the whole expression, and >> align in properly, and >> don't move reg==AUX_REG check to a different line. >> Subject is not warranted. I don't think it's a simplification. > > It's not really a simplification, > gcc should emit the same object code.
exactly.
>> imo existing code is fine and I don't think the time spent >> reviewing such changes is worth it when there is no >> improvement in readability. > > Is there any value in reordering these tests for frequency > or maybe using | instead of || to avoid multiple jumps?
probably not. It's not a critical path. compiler may fuse conditions depending on values anyway. If it was a critical path, we could have used (1 << reg) & mask trick. I picked explicit 'return true' else 'return false' here, because it felt easier to read. Just a matter of taste.
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