Richard Biener <richard.guent...@gmail.com> writes: > Note that combine does not apply because %eax is used multiple > times. This also means that for code-size the combining is not a good > idea.
Though the lea instruction seems rather large, so in fact the code is a fair bit smaller without it, e.g. as generated by clang/llvm: clang/llvm 3.1 (-O2 -m32): 00000000 <foo>: 0: 8b 44 24 08 mov 0x8(%esp),%eax 4: 8b 4c 24 04 mov 0x4(%esp),%ecx 8: 8b 14 c1 mov (%ecx,%eax,8),%edx b: 89 15 00 00 00 00 mov %edx,0x0 11: 89 04 c1 mov %eax,(%ecx,%eax,8) 14: 31 c0 xor %eax,%eax 16: c3 ret gcc 4.8 20130113 (-O2 -m32): 00000000 <foo>: 0: 8b 54 24 08 mov 0x8(%esp),%edx 4: 8d 04 d5 00 00 00 00 lea 0x0(,%edx,8),%eax b: 03 44 24 04 add 0x4(%esp),%eax f: 8b 08 mov (%eax),%ecx 11: 89 0d 00 00 00 00 mov %ecx,0x0 17: 89 10 mov %edx,(%eax) 19: 31 c0 xor %eax,%eax 1b: c3 ret -miles -- Ich bin ein Virus. Mach' mit und kopiere mich in Deine .signature.
