Null pointer check elimination

[Jeff Law]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 03/08/11 03:48, sankar chebolu wrote:
> foo (char *x)
> {
>   char ret = *x;
> 
>   if (x)
>     com();
>   else
>     bar();
>   return ret;
> }
> 

GCC 4.1 is insanely old and the optimizer may not have been working for
some reason.  We don't really work on GCC 4.1 anymore.

Compiling your testcase with -O2 using GCC 4.5.1 I get:

.globl foo
	.type	foo, @function
foo:
.LFB0:
	.cfi_startproc
	pushq	%rbx
	.cfi_def_cfa_offset 16
	.cfi_offset 3, -16
	movsbl	(%rdi), %ebx
	xorl	%eax, %eax
	call	com
	movl	%ebx, %eax
	popq	%rbx
	.cfi_def_cfa_offset 8
	ret
	.cfi_endproc
.LFE0:

Clearly the null pointer check was eliminated.

jeff
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.11 (GNU/Linux)
Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/

iQEcBAEBAgAGBQJNdj0DAAoJEBRtltQi2kC7p5AH/33tN/amBk2yAIw1J6sxwvQP
1R1ckU3Q9Je5xt9QbRG7N3oooiiC+TE6SbeHmPSFSiJcyY86AkJmotlhzVx65dF1
jiYDsbTkIQsCHT1KofKm5QcAGFZdMUEafwt0hzlewRH6ZIc0cNogZGvg99OWTuPY
7izhSEXKRPxkhvnYJdxb7Wk3cPzt89V1xJzVZ8lJJek7HvjrDLq9EzYtkvHeBmN8
zV4rl4Sp0iIslQV3Y5gEDNJH+84GpZ8sNLRPoCNn+O7RRx+LWEzfc3oh+mddgFx/
G7Tk04SULkFLNK9fAdz3o5Oa+OtnZRvPiFyfS6qSWcHulRgm13hPNGwtQd17EKA=
=blOC
-----END PGP SIGNATURE-----