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SubjectRe: [PATCH] x86: bpf_jit_comp: simplify trivial boolean return
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On Thu, 2014-12-04 at 07:56 -0800, Alexei Starovoitov wrote:
> On Thu, Dec 4, 2014 at 1:26 AM, Joe Perches <joe@perches.com> wrote:
> > On Thu, 2014-11-27 at 10:49 -0800, Joe Perches wrote:
> >> On Thu, 2014-11-27 at 12:25 +0000, David Laight wrote:
> >> > Why the change in data?
> >>
> >> btw: without gcov and using -O2
> >>
> >> $ size arch/x86/net/bpf_jit_comp.o*
> >> text data bss dec hex filename
> >> 9671 4 0 9675 25cb arch/x86/net/bpf_jit_comp.o.new
> >> 10679 4 0 10683 29bb arch/x86/net/bpf_jit_comp.o.old
> >
> > Alexei?
> >
> > Is this 10% reduction in size a good reason to change the code?
>
> yes.
> I believe you're seeing it with gcc 4.9. I wanted to double
> check what 4.6 and 4.7 are doing. If they're not suddenly
> increase code size then resubmit it for inclusion please.

I get these sizes for these compilers
(x86-64, -O2, without profiling)

$ size arch/x86/net/bpf_jit_comp.o*
text data bss dec hex filename
9266 4 0 9270 2436 arch/x86/net/bpf_jit_comp.o.4.4.new
10042 4 0 10046 273e arch/x86/net/bpf_jit_comp.o.4.4.old
9109 4 0 9113 2399 arch/x86/net/bpf_jit_comp.o.4.6.new
9717 4 0 9721 25f9 arch/x86/net/bpf_jit_comp.o.4.6.old
8789 4 0 8793 2259 arch/x86/net/bpf_jit_comp.o.4.7.new
10245 4 0 10249 2809 arch/x86/net/bpf_jit_comp.o.4.7.old
9671 4 0 9675 25cb arch/x86/net/bpf_jit_comp.o.4.9.new
10679 4 0 10683 29bb arch/x86/net/bpf_jit_comp.o.4.9.old

I am a bit surprised by the size variations




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