On Tue, Oct 4, 2011 at 11:51 AM, Uros Bizjak <ubiz...@gmail.com> wrote: > On Tue, Oct 4, 2011 at 8:37 PM, H.J. Lu <hjl.to...@gmail.com> wrote: > >>>>> OTOH, x86_64 and i686 targets can also benefit from this change. If >>>>> combine can't create more complex address (covered by lea), then it >>>>> will simply propagate memory operand back into the add insn. It looks >>>>> to me that we can't loose here, so: >>>>> >>>>> /* Improve address combine. */ >>>>> if (code == PLUS && MEM_P (src2)) >>>>> src2 = force_reg (mode, src2); >>>>> >>>>> Any opinions? >>>>> >>>> >>>> It doesn't work with 64bit libstdc++: >>> >>> Yeah, yeah. ix86_output_mi_thunk has some ... issues. >>> >>> Please try attached patch that introduces ix86_emit_binop and uses it >>> in a bunch of places. > >> I tried it on GCC. There are no regressions. The bugs are fixed for x32. >> Here are size comparison with GCC runtime libraries on ia32, x32 and >> x86-64: > >> 884093 18600 27064 929757 e2fdd old libstdc++.so >> 884189 18600 27064 929853 e303d new libs/libstdc++.so >> >> The new code is >> >> mov 0xc(%edi),%eax >> mov %eax,0x8(%esi) >> mov -0xc(%eax),%eax >> mov 0x10(%edi),%edx >> lea 0x8(%esi,%eax,1),%eax >> >> The old one is >> >> mov 0xc(%edi),%edx >> lea 0x8(%esi),%eax >> mov %edx,0x8(%esi) >> add -0xc(%edx),%eax >> mov 0x10(%edi),%edx > > The new code merged lea+add into one lea, so it looks quite OK to me. > > Do you have some performance numbers? >
I will report performance numbers in a few days. -- H.J.
