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[Bug rtl-optimization/63718] [5 Regression] ARM Thumb1 bootstrap fail after fuse-caller-save info in cprop-hardreg
- From: "vries at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 03 Nov 2014 11:13:58 +0000
- Subject: [Bug rtl-optimization/63718] [5 Regression] ARM Thumb1 bootstrap fail after fuse-caller-save info in cprop-hardreg
- Auto-submitted: auto-generated
- References: <bug-63718-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63718
--- Comment #7 from vries at gcc dot gnu.org ---
(In reply to Joey Ye from comment #6)
> (In reply to vries from comment #5)
> > Could you try out the patch and see if it fixes things for you?
> >
> Tom, thanks for the quick action. Apparantly this patch should recover the
> bootstrap. I will test it and come back to you (bootstraping thumb1 with
> qemu takes hours!)
>
Great :)
> However, I think the fix is too conservative. There are plenty of chances
> that r0-r3 will not be clobbered by return. For example armv6-m will pretty
> much never uses r0-r3 implicitly.
Indeed, the patch is conservative, but that's not such a bad idea for a
correctness fix. We can always folllow up with a more optimal patch.