> > * Without PRE,
> >
> > Path1:
> >        movl    $2, %eax
> >        cmpl    $1, %eax
> >        je      .L3
> >
> > Path2:
> >        movb    $3, %al
> >        cmpl    $1, %eax
> >        je      .L3
> >
> > Path3:
> >        cmpl    $1, %eax
> >        jne     .L14
> >
> > * With PRE,
> >
> > Path1:
> >        movl    $1, %ebx
> >        movl    $2, %eax
> >        testb   %bl, %bl
> >        je      .L3
> >
> > Path2:
> >        movl    $1, %ebx
> >        movb    $3, %al
> >        testb   %bl, %bl
> >        je      .L3
> >
> > Path3:
> >        cmpl    $1, %eax
> >        setne   %bl
> >        testb   %bl, %bl
> >        jne     .L14
> >
> > Do you have any more thoughts?
> 
> It seems to me that with PRE all the testb %bl, %bl
> should be evaluated at compile-time considering the
> preceeding movl $1, %ebx.  Am I missing something?
> 

Yes. Can this be done by PRE or any other optimizations in middle end?

Thanks,
-Jiangning

> Richard.
> 




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