------- Comment #9 from ramana dot radhakrishnan at arm dot com 2010-04-12
09:51 -------
Subject: Re: [4.5/4.6 Regression] Invalid code when
building gentoo pax-utils-0.1.19 with -Os optimizations
On Mon, 2010-04-12 at 09:34 +0000, siarhei dot siamashka at gmail dot
com wrote:
>
> ------- Comment #8 from siarhei dot siamashka at gmail dot com 2010-04-12
> 09:34 -------
> (In reply to comment #7)
> > Patch submitted here.
> >
> > http://gcc.gnu.org/ml/gcc-patches/2010-04/msg00401.html
>
> Thank you. I have been testing it for two days already.
>
> It really helps (in the sense that it is apparently better to have this fix
> than not to have). I have bootstrapped the hard vfp system successfully and
> did
> not notice any other problems so far. Btw, miscompilation (of all the same
> package) also happens with -O2 optimization settings in some other place, but
> I
> did not try to investigate where exactly it fails.
>
> But I understand that it is just a workaround for the problem which happens
> somewhere in the upper layer? If REV instruction did not actually support
> conditional execution, then the fix would require actually finding the real
> cause.
There were 2 issues, one is that REV isn't marked as being allowed
conditional and the other is that the CCFSM state machine appears to go
wrong in this particular case which is something I need to investigate
when I have some more free time. (Note this is ARM backend specific
only.)
Thus the fix isn't a work-around because it introduces predicated
support for something like the REV instruction which is the right thing
to do here.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43698
