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x86: bpf_jit_comp: Reduce is_ereg() code size

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Use the (1 << reg) & mask trick to reduce code size.

x86-64 size difference -O2 without profiling for various
gcc versions:

$ 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

Signed-off-by: Joe Perches <joe@perches.com>
Tested-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Joe Perches 2014-12-04 15:00:48 -08:00 committed by David S. Miller
parent 57d743a3de
commit d148134be5
1 changed files with 5 additions and 5 deletions
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10
arch/x86/net/bpf_jit_comp.c
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@ -135,11 +135,11 @@ 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 (1 << reg) & (BIT(BPF_REG_5) |
BIT(AUX_REG) |
BIT(BPF_REG_7) |
BIT(BPF_REG_8) |
BIT(BPF_REG_9));
}
/* add modifiers if 'reg' maps to x64 registers r8..r15 */