* Deletion of trivial insn during IRA
@ 2011-10-03 11:17 Paulo J. Matos
2011-10-03 20:24 ` Ian Lance Taylor
0 siblings, 1 reply; 3+ messages in thread
From: Paulo J. Matos @ 2011-10-03 11:17 UTC (permalink / raw)
To: gcc
Hi,
I am trying to find where IRA, is deleting trivial insn like:
(set r1 r1)
The problem I am facing is that I have managed to convince GCC to handle
moves that clobber RCC like:
(parallel [(set reg1 reg2) (clobber rcc)])
However, I am getting loads of insn like:
(parallel [(set r1 r2) (clobber rcc)])
in the insn stream after IRA. This is also blocking some later
optimisations.
I am trying to find where GCC actually removes insns where source and
dest are the same. I understand that if there's a general clobber then
the insn shouldn't be removed, however if the clobber is on the flags
register then it should go ahead and remove it anyway.
Can someone guide me to the right place where this is happening?
Cheers,
--
PMatos
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Deletion of trivial insn during IRA
2011-10-03 11:17 Deletion of trivial insn during IRA Paulo J. Matos
@ 2011-10-03 20:24 ` Ian Lance Taylor
2011-10-04 8:01 ` Paulo J. Matos
0 siblings, 1 reply; 3+ messages in thread
From: Ian Lance Taylor @ 2011-10-03 20:24 UTC (permalink / raw)
To: Paulo J. Matos; +Cc: gcc
paulo@matos-sorge.com (Paulo J. Matos) writes:
> I am trying to find where IRA, is deleting trivial insn like:
> (set r1 r1)
Search for "Discard obvious no-ops" in the function reload in the file
gcc/reload1.c.
Ian
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Deletion of trivial insn during IRA
2011-10-03 20:24 ` Ian Lance Taylor
@ 2011-10-04 8:01 ` Paulo J. Matos
0 siblings, 0 replies; 3+ messages in thread
From: Paulo J. Matos @ 2011-10-04 8:01 UTC (permalink / raw)
To: gcc
Ian Lance Taylor <iant@google.com> writes:
> paulo@matos-sorge.com (Paulo J. Matos) writes:
>
>> I am trying to find where IRA, is deleting trivial insn like:
>> (set r1 r1)
>
> Search for "Discard obvious no-ops" in the function reload in the file
> gcc/reload1.c.
Thanks, that's exactly it.
--
PMatos
^ permalink raw reply [flat|nested] 3+ messages in thread
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2011-10-03 11:17 Deletion of trivial insn during IRA Paulo J. Matos
2011-10-03 20:24 ` Ian Lance Taylor
2011-10-04 8:01 ` Paulo J. Matos
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