https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94892
Harald van Dijk <harald at gigawatt dot nl> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |harald at gigawatt dot nl
--- Comment #3 from Harald van Dijk <harald at gigawatt dot nl> ---
Changing the test slightly to
inline int sign(int x)
{
return (x >> 31) | ((unsigned)-x >> 31);
}
void f1(void);
void f2(void);
void f(int x)
{
if (sign(x) > -1)
f1();
else
f2();
}
shows at -O3 with LLVM:
f:
test edi, edi
js .LBB0_2
jmp f1
.LBB0_2:
jmp f2
whereas GCC produces:
f:
mov eax, edi
sar edi, 31
neg eax
shr eax, 31
or edi, eax
cmp edi, -1
je .L2
jmp f1
.L2:
jmp f2
In that example, LLVM is doing much better.
