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Re: regrename creates invalid insn
- From: Bernd Schmidt <bernds at codesourcery dot com>
- To: Steven Bosscher <stevenb dot gcc at gmail dot com>
- Cc: Andreas Schwab <schwab at linux-m68k dot org>, Ian Lance Taylor <iant at google dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Thu, 12 Jul 2012 00:38:40 +0200
- Subject: Re: regrename creates invalid insn
- References: <m2d38hvigj.fsf@igel.home> <mcrlin5bkyx.fsf@dhcp-172-18-216-180.mtv.corp.google.com> <m24nttv7ja.fsf@igel.home> <mcr4nttbhzc.fsf@dhcp-172-18-216-180.mtv.corp.google.com> <m2zkbltprm.fsf@igel.home> <m2r4wxtmim.fsf@igel.home> <4F707DAE.2070201@codesourcery.com> <m2sjgvic3r.fsf@igel.home> <4FFDF09B.9040104@codesourcery.com> <CABu31nMGD8U2ps3O2SNuFED55foR35vVFDJEEi9dzqJOWdCyxw@mail.gmail.com>
On 07/12/2012 12:10 AM, Steven Bosscher wrote:
> On Wed, Jul 11, 2012 at 11:31 PM, Bernd Schmidt <bernds@codesourcery.com> wrote:
>> On 03/26/2012 06:03 PM, Andreas Schwab wrote:
>>> Bernd Schmidt <bernds@codesourcery.com> writes:
>>>
>>>> Does 4.7 still have the failure at all?
>>>
>>> Yes, see PR52573.
>>
>> Well, I still think having both REG_DEAD and REG_UNUSED for the same reg
>> is bogus, but fixing that causes trouble in reg-stack.
>
> Oh? Before, during, or after reg-stack? IIRC reg-stack re-creates the
> notes from scratch for the stack registers.
During - it relies on the ones it finds. Search for a comment mentioning
fix_truncdi in a CLOBBER case.
> Is it possible to "filter" one of the notes (REG_DEAD or REG_UNUSED)
> out in add_reg_note? IMHO you're right that having both is bogus...
Not even necessary, there's already code in df-problems to avoid adding
REG_DEAD when it's already made a REG_UNUSED - but that code is
explicitly disabled for CLOBBERs. Go figure.
Bernd