Re: [PATCH 2/2 v3][IRA,LRA] Fix PR86939, IRA incorrectly creates an interference between a pseudo register and a hard register

[Peter Bergner <bergner at linux dot ibm dot com>]

On 10/11/18 2:40 PM, Jeff Law wrote:
> On 10/11/18 1:23 PM, Peter Bergner wrote:
>> On 10/11/18 1:18 PM, Peter Bergner wrote:
>>> Ok, after working in gdb, I see that the PA-RISC port still uses reload
>>> and not LRA, but it too seems to have the same issue of reusing input
>>> regs that have REG_DEAD notes, so the question still stands.  It's just
>>> that whatever fix we come up with will have to be to both LRA and reload.
>>
>> On second thought, I'm thinking we should just leave reload alone and
>> only fix this in LRA.  That means we'd have to disable the reg copy
>> handling when not using LRA though, which might be another reason to
>> get targets to move to LRA?  I've verified the following patch gets
>> the PA-RISC test case to pass again.  Thoughts?
>>
>> If ok, I still have to dig into the fails we're seeing on LRA targets.
> Hmmm.  Interesting.  I wonder if all the failing targets were reload
> targets.....  If so, this may be the way forward -- I certainly don't
> want to spend much, if any, time fixing reload.
> 
> I'm in the middle of something, but will try to look at each of the
> failing targets and confirm they use reload by default.

These are the easy ones (they default to reload):

bergner@pike:~/gcc/gcc-fsf-mainline/gcc/config$ grep -r TARGET_LRA_P | grep false | sort
alpha/alpha.c:#define TARGET_LRA_P hook_bool_void_false
avr/avr.c:#define TARGET_LRA_P hook_bool_void_false
bfin/bfin.c:#define TARGET_LRA_P hook_bool_void_false
c6x/c6x.c:#define TARGET_LRA_P hook_bool_void_false
cr16/cr16.c:#define TARGET_LRA_P hook_bool_void_false
cris/cris.c:#define TARGET_LRA_P hook_bool_void_false
epiphany/epiphany.c:#define TARGET_LRA_P hook_bool_void_false
fr30/fr30.c:#define TARGET_LRA_P hook_bool_void_false
frv/frv.c:#define TARGET_LRA_P hook_bool_void_false
h8300/h8300.c:#define TARGET_LRA_P hook_bool_void_false
ia64/ia64.c:#define TARGET_LRA_P hook_bool_void_false
iq2000/iq2000.c:#define TARGET_LRA_P hook_bool_void_false
lm32/lm32.c:#define TARGET_LRA_P hook_bool_void_false
m32c/m32c.c:#define TARGET_LRA_P hook_bool_void_false
m32r/m32r.c:#define TARGET_LRA_P hook_bool_void_false
m68k/m68k.c:#define TARGET_LRA_P hook_bool_void_false
mcore/mcore.c:#define TARGET_LRA_P hook_bool_void_false
microblaze/microblaze.c:#define TARGET_LRA_P hook_bool_void_false
mmix/mmix.c:#define TARGET_LRA_P hook_bool_void_false
mn10300/mn10300.c:#define TARGET_LRA_P hook_bool_void_false
moxie/moxie.c:#define TARGET_LRA_P hook_bool_void_false
msp430/msp430.c:#define TARGET_LRA_P hook_bool_void_false
nvptx/nvptx.c:#define TARGET_LRA_P hook_bool_void_false
pa/pa.c:#define TARGET_LRA_P hook_bool_void_false
rl78/rl78.c:#define TARGET_LRA_P hook_bool_void_false
spu/spu.c:#define TARGET_LRA_P hook_bool_void_false
stormy16/stormy16.c:#define TARGET_LRA_P hook_bool_void_false
tilegx/tilegx.c:#define TARGET_LRA_P hook_bool_void_false
tilepro/tilepro.c:#define TARGET_LRA_P hook_bool_void_false
vax/vax.c:#define TARGET_LRA_P hook_bool_void_false
visium/visium.c:#define TARGET_LRA_P hook_bool_void_false
xtensa/xtensa.c:#define TARGET_LRA_P hook_bool_void_false

These are harder since they support -mlra:

arc/arc.c:#define TARGET_LRA_P arc_lra_p
ft32/ft32.c:#define TARGET_LRA_P ft32_lra_p
mips/mips.c:#define TARGET_LRA_P mips_lra_p
pdp11/pdp11.c:#define TARGET_LRA_P pdp11_lra_p
powerpcspe/powerpcspe.c:#define TARGET_LRA_P rs6000_lra_p
rx/rx.c:#define TARGET_LRA_P 				rx_enable_lra
s390/s390.c:#define TARGET_LRA_P s390_lra_p
sh/sh.c:#define TARGET_LRA_P sh_lra_p
sparc/sparc.c:#define TARGET_LRA_P sparc_lra_p

Quickly looking into their *.opt files, the follwoing default to LRA:
  mips, s390
while these default to reload:
  ft32, sh4
and these I'm not sure of without looking deeper:
  arc, pdp11, powerpcspe, rx, sparc

...if that helps.

Peter