Re: [PATCH 01/16] perf: Unified API to record selective sets of arch registers

[Peter Zijlstra <a.p.zijlstra@chello.nl>]

On Wed, 2012-05-23 at 21:32 +0200, Jiri Olsa wrote:
> +static inline u64 perf_reg_value(struct pt_regs *regs, int idx)
> +{
> +       switch (idx) {
> +       case PERF_X86_32_REG_EAX:
> +               return regs->ax;
> +       case PERF_X86_32_REG_EBX:
> +               return regs->bx;
> +       case PERF_X86_32_REG_ECX:
> +               return regs->cx;
> +       case PERF_X86_32_REG_EDX:
> +               return regs->dx;
> +       case PERF_X86_32_REG_ESI:
> +               return regs->si;
> +       case PERF_X86_32_REG_EDI:
> +               return regs->di;
> +       case PERF_X86_32_REG_EBP:
> +               return regs->bp;
> +       case PERF_X86_32_REG_ESP:
> +               return regs->sp;
> +       case PERF_X86_32_REG_EIP:
> +               return regs->ip;
> +       case PERF_X86_32_REG_FLAGS:
> +               return regs->flags;
> +       case PERF_X86_32_REG_CS:
> +               return regs->cs;
> +       case PERF_X86_32_REG_DS:
> +               return regs->ds;
> +       case PERF_X86_32_REG_ES:
> +               return regs->es;
> +       case PERF_X86_32_REG_FS:
> +               return regs->fs;
> +       case PERF_X86_32_REG_GS:
> +               return regs->gs;
> +       }
> +
> +       return 0;
> +} 

This is just sad... is there really no saner way to write this? I
suppose you're going to iterate your sample_regs bitmap and call this
function for every bit. GCC isn't known to generate particularly sane
code for switches :/