http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57536
--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> ---
Also -Os generates larger code:
[hjl@gnu-6 gcc]$ gcc -S -Os -m32 x.i
[hjl@gnu-6 gcc]$ cat x.s
.file "x.i"
.text
.globl foo
.type foo, @function
foo:
.LFB0:
.cfi_startproc
pushl %ebp
.cfi_def_cfa_offset 8
.cfi_offset 5, -8
xorl %eax, %eax
movl %esp, %ebp
.cfi_def_cfa_register 5
orl $-1, %ecx
pushl %edi
.cfi_offset 7, -12
movl 8(%ebp), %edi
repnz scasb
popl %edi
.cfi_restore 7
popl %ebp
.cfi_restore 5
.cfi_def_cfa 4, 4
notl %ecx
leal -1(%ecx), %eax
ret
