Il 09/10/2012 21:55, Aurelien Jarno ha scritto:
> This patch series rework the liveness analysis and register allocator
> in order to generate more optimized code, by avoiding a lot of move
> instructions. I have measured a 9% performance improvement in user mode
> and 4% in system mode.
>
> The idea behind this patch series is to free registers as soon as the
> temps are not used anymore instead of waiting for a basic block end or
> an op with side effects.
Would it make any sense to express the saves as real TCG ops? This
would have a couple of advantages:
- more copy propagation and dead code elimination. Something like this:
mov_i64 cc_dst,rax
right now is compiled as follows:
0x5555557ac37a: mov %rbp,(%r14) # spill rax
0x5555557ac381: mov (%r14),%rbp # load rax from memory
0x5555557ac38f: mov %rbp,0x98(%r14) # spill cc_dst to memory
while expressing spills as TCG ops would turn the above into effectively
st_i64 rax, env, $0x98
- constant propagation using constraints. This would let tcg-i386 use
effectively the mov $imm,(addr) instruction for spills of known-constant
values.
Paolo
