[Bug target/59968] Unused BT patterns
hjl.tools at gmail dot com
gcc-bugzilla@gcc.gnu.org
Tue Jan 28 18:22:00 GMT 2014
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59968
--- Comment #11 from H.J. Lu <hjl.tools at gmail dot com> ---
For
int bar1;
void
__attribute__((noinline))
foo1 (int y)
{
if ((bar1 & (1 << y)))
bar1 &= ~(1 << y);
}
we generate
.cfi_startproc
movl bar1(%rip), %eax
btl %edi, %eax
jnc .L1
movl $-2, %edx
movl %edi, %ecx
roll %cl, %edx
andl %edx, %eax
movl %eax, bar1(%rip)
.L1:
rep ret
I expect
btr %edi, bar2(%rip)
ret
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