>>>>> "Momchil" == Momchil Velikov <velco@fadata.bg> writes:
Phil> Actually, if you try compiling that file with the patch and
Phil> without it, they do not turn out the same. I tried without -O,
Phil> with -O2, and with -O3.
One more example:
x1.c:
-----
int foo (), bar ();
int
baz ()
{
int ret;
if (__builtin_expect (foo (), 0))
{
ret = 0;
goto out;
}
bar ();
ret = 1;
out:
return ret;
}
x2.c:
-----
int foo (), bar ();
int
baz ()
{
int ret;
if (__builtin_expect (foo (), 0))
{
ret = 0;
return ret;
}
bar ();
ret = 1;
out:
return ret;
}
gcc -S -O3 -fomit-frame-pointer x1.c x2.c
x1.s:
-----
.file "x1.c"
.text
.p2align 4,,15
.globl baz
.type baz, @function
baz:
subl $12, %esp
call foo
xorl %edx, %edx
testl %eax, %eax
jne .L3
call bar
movl $1, %edx
.L3:
movl %edx, %eax
addl $12, %esp
ret
.size baz, .-baz
.ident "GCC: (GNU) 3.3.2"
x2.s:
-----
.file "x2.c"
.text
.p2align 4,,15
.globl baz
.type baz, @function
baz:
subl $12, %esp
call foo
xorl %edx, %edx
testl %eax, %eax
jne .L1
.L3:
call bar
movl $1, %edx
.L1:
movl %edx, %eax
addl $12, %esp
ret
.size baz, .-baz
.ident "GCC: (GNU) 3.3.2"
Right, they are identical :)
~velco
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