[Bug optimization/12395] Suboptimal code with global variables

[segher at d12relay01 dot megacenter dot de dot ibm dot com]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12395



------- Additional Comments From segher at d12relay01 dot megacenter dot de dot ibm dot com  2003-09-29 14:39 -------
Subject: Re:  New: Suboptimal code with global variables

> void foo() {
>         extern int a;
>         if(++a) ++a;
> }

> This is subobtimal. The optimal code should be:
> 
> foo:
>         addl    $1,a
>         je      .L1
>         addl    $1,a
> .L1:
>         ret

[I haven't written x86 assembler for a long time, but...]

That code isn't optimal either; something like

foo:
	addl	$1,a
	sbbl	$-1,a
	ret

would be even better :-)