From: Joe Perches Date: Thu, 4 Dec 2014 23:00:48 +0000 (-0800) Subject: x86: bpf_jit_comp: Reduce is_ereg() code size X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=d148134be51fe05271ec8d47fe8c815bdee2b8e7;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git x86: bpf_jit_comp: Reduce is_ereg() code size 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 Tested-by: Alexei Starovoitov Signed-off-by: David S. Miller --- diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 3f627345d51c..09e2ceaf13cb 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -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 */