Re: [patch,mips] avoid invalid register for JALR

[Sandra Loosemore <sandra at codesourcery dot com>]

On 05/13/2014 03:41 PM, Richard Sandiford wrote:
> Sandra Loosemore <sandra@codesourcery.com> writes:
> > When I was trying to benchmark another patch (which I'll be sending
> > along shortly) with CSiBE for -mabi=64, I ran into an assembler error
> > like this:
> >
> > /tmp/ccJv2faG.s: Assembler messages:
> > /tmp/ccJv2faG.s:1605: Error: a destination register must be supplied
> > `jalr $31'
>
> JALR patterns should have an explicit clobber of $31, which I thought
> was also supposed to stop $31 from being used as the call address.

Hmmmmm.  Yes, that ought to work, in theory....

> Do you have a testcase?

I can reproduce the error in a current mipsisa64-elfoabi build, with my 
patch to delete ADJUST_REG_ALLOC_ORDER applied.  It triggers on this 
file from CSiBE:

mipsisa64-elfoabi-gcc -c -mabi=64 -O2 -fno-common -w 
csibe/src/./ttt-0.10.1.preproc/src/connect4.i

> > I had some difficulty in regression-testing this patch because of
> > unrelated problems on trunk in the past week -- at first I was getting
> > ICEs due to a null pointer dereference in tree code, then when I tried
> > again a couple days later trunk was not even building.
>
> Could you give more details?

I think both of these problems have been fixed now, or at least I can 
build things again.  The tree null pointer dereference was probably the 
same thing you discussed here

https://gcc.gnu.org/ml/gcc-patches/2014-05/msg00677.html

and the build failures seemed like this one

https://gcc.gnu.org/ml/gcc-patches/2014-05/msg00500.html

-Sandra