http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13355
Steven Bosscher <steven at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |steven at gcc dot gnu.org --- Comment #10 from Steven Bosscher <steven at gcc dot gnu.org> 2012-11-08 22:46:53 UTC --- (In reply to comment #1) > Created attachment 5301 [details] > example .c file that shows behavior with > gcc -march=i686 -mtune=i686 -fomit-frame-pointer -O2 test.c GCC 4.7.1 compiles the two interesting functions in the test case to: op_cmovl_EAX_T1_T0: testl %ebx, %ebx je .L2 movl %esi, 0(%ebp) .L2: ret op_imull_EAX_T0: subl $20, %esp movl 0(%ebp), %eax imull %ebx movl %eax, (%esp) movl %eax, 0(%ebp) movl (%esp), %eax movl %edx, 4(%esp) movl %edx, 8(%ebp) movl %eax, %edx movl %eax, 8(%esp) sarl $31, %edx movl 4(%esp), %eax movl %edx, 12(%esp) cmpl %eax, 12(%esp) setne %al movzbl %al, %eax movl %eax, 32(%ebp) addl $20, %esp ret Trunk r193340 produces the following: op_cmovl_EAX_T1_T0: testl %ebx, %ebx je .L2 movl %esi, 0(%ebp) .L2: ret op_imull_EAX_T0: subl $12, %esp movl %ebx, %eax imull 0(%ebp) movl %eax, 0(%ebp) movl %eax, (%esp) sarl $31, %eax movl %eax, 4(%esp) xorl %eax, %eax cmpl %edx, 4(%esp) movl %edx, 8(%ebp) setne %al movl %eax, 32(%ebp) addl $12, %esp ret