Re: regrename: don't overflow insn_rr_info

[Bernd Schmidt <bschmidt at redhat dot com>]

On 11/06/2015 12:17 PM, Ramana Radhakrishnan wrote:
> On 06/11/15 11:08, Bernd Schmidt wrote:
> > This one is a fix for something that could currently only affect c6x, but I have code that exposes it on i386.
> >
> > When optionally gathering operand info in regrename, we can overflow the array in certain situations. This can occur when we have a situation where a value is constructed in multiple small registers and then accessed as a larger one (CDImode in the testcase I have). In that case we enter the "superset" path, which fails the involved chains, but the smaller pieces still all get seen by record_operand_use, and there may be more of them than MAX_REGS_PER_ADDRESS.
> >
> > The following fixes it. Bootstrapped and tested  with -frename-registers enabled at -O1 on x86_64-linux. Ok?
> >
> >
> > Bernd
>
> This sounds like it will fix http://gcc.gnu.org/PR66785 ...

Ah, I didn't realize something else was using this functionality:

gcc/config/aarch64/cortex-a57-fma-steering.c
1025:  regrename_init (true);

Yeah, the description of that bug makes it sound like the same issue.


Bernd