------- Comment #2 from tbptbp at gmail dot com 2006-08-11 06:07 ------- Subject: Re: missed optimization, redundant scalar SSE comparisons
On 11 Aug 2006 05:52:26 -0000, pinskia at gcc dot gnu dot org <[EMAIL PROTECTED]> wrote: > Using unsigned char and a temp variable removes the problem of zero extending > the grabbing of the flags. For sure the code looks better when sprinkling uchars - modulo partial stalls, but gcc decidedly doesn't want to fuse those comparisons ;) 00418ed0 <kdlib::lbox_t::set_category(unsigned int, float, kdlib::sideness_t)>: 418ed0: sub $0x10,%esp 418ed3: mov %esi,0x4(%esp) 418ed7: mov 0x14(%esp),%esi 418edb: mov %edi,0x8(%esp) 418edf: mov 0x18(%esp),%edi 418ee3: mov %ebx,(%esp) 418ee6: mov %ebp,0xc(%esp) 418eea: movzbl 0x34(%esi),%edx 418eee: movss 0x1c(%esp),%xmm1 418ef4: shl $0x4,%edi 418ef7: movzbl 0x18(%esp),%ecx 418efc: movss (%edi,%esi,1),%xmm0 418f01: comiss %xmm0,%xmm1 418f04: seta %al 418f07: comiss %xmm1,%xmm0 418f0a: mov %eax,%ebp 418f0c: mov %edx,%eax 418f0e: sete %bl 418f11: shr $0x3,%al 418f14: and $0x7,%eax 418f17: sar %cl,%eax 418f19: mov 0x20(%esp),%ecx 418f1d: and %eax,%ebx 418f1f: comiss 0x8(%edi,%esi,1),%xmm1 418f24: setb %al 418f27: and $0xfffffff8,%edx 418f2a: and %ebp,%eax 418f2c: and $0x1,%ebx 418f2f: cmove %ebp,%ecx 418f32: or %eax,%edx 418f34: and $0x3,%ecx 418f37: add %ecx,%ecx 418f39: or %ecx,%edx 418f3b: mov %dl,0x34(%esi) 418f3e: mov (%esp),%ebx 418f41: mov 0x4(%esp),%esi 418f45: mov 0x8(%esp),%edi 418f49: mov 0xc(%esp),%ebp 418f4d: add $0x10,%esp 418f50: ret -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28691
