[Bug target/111225] ICE in curr_insn_transform, unable to generate reloads for xor, since r14-2447-g13c556d6ae84be

[liuhongt at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111225

liuhongt at gcc dot gnu.org changed:

   What|Removed |Added

 Status|UNCONFIRMED |RESOLVED
 CC||liuhongt at gcc dot gnu.org
 Resolution|--- |FIXED

--- Comment #5 from liuhongt at gcc dot gnu.org ---
.

[Bug target/111225] ICE in curr_insn_transform, unable to generate reloads for xor, since r14-2447-g13c556d6ae84be

[cvs-commit at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111225

--- Comment #4 from CVS Commits  ---
The master branch has been updated by Vladimir Makarov :

https://gcc.gnu.org/g:f7bca44d97ad01b39f9d6e7809df7bf517eeb2fb

commit r14-3783-gf7bca44d97ad01b39f9d6e7809df7bf517eeb2fb
Author: Vladimir N. Makarov 
Date:   Thu Sep 7 09:59:10 2023 -0400

[LRA]: Don't reuse chosen insn alternative with special memory constraint

To speed up GCC, LRA reuses chosen alternative from previous
constraint subpass.  A spilled pseudo is considered ok for any memory
constraint although stack slot assigned to the pseudo later might not
satisfy the chosen alternative constraint.  As we don't consider all insn
alternatives on the subsequent LRA sub-passes, it might result in LRA
failure
to generate the correct insn.  This patch solves the problem.

gcc/ChangeLog:

PR target/111225
* lra-constraints.cc (goal_reuse_alt_p): New global flag.
(process_alt_operands): Set up the flag.  Clear flag for chosen
alternative with special memory constraints.
(process_alt_operands): Set up used insn alternative depending on
the flag.

gcc/testsuite/ChangeLog:

PR target/111225
* gcc.target/i386/pr111225.c: New test.

[Bug target/111225] ICE in curr_insn_transform, unable to generate reloads for xor, since r14-2447-g13c556d6ae84be

[vmakarov at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111225

--- Comment #3 from Vladimir Makarov  ---
I've reproduced the bug.

Just removing `else if (spilled_pseudo_p (op))` for CT_SPECIAL_MEMORY will
break a lot targets but this is right that this code is a reason for the bug.

I have ideas how to fix it and I'll fix it on the next week.

[Bug target/111225] ICE in curr_insn_transform, unable to generate reloads for xor, since r14-2447-g13c556d6ae84be

[crazylht at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111225

--- Comment #2 from Hongtao.liu  ---
(In reply to Hongtao.liu from comment #1)
> So reload thought CT_SPECIAL_MEMORY is always win for spilled_pesudo_p, but
> here Br should be a vec_dup:mem which doesn't match spilled_pseduo_p.
>  
>   case CT_SPECIAL_MEMORY:
> if (satisfies_memory_constraint_p (op, cn))
>   win = true;
> else if (spilled_pseudo_p (op))
>   win = true;
> break;

vmBr constraint is ok as long as m is matched before Br, but here m in invalid
then exposed the problem.
The backend walkaround is disabling Br when m is not availble.

Or the middle-end fix should be removing win for spilled_pseudo_p (op) in
CT_SPECIAL_MEMORY.

[Bug target/111225] ICE in curr_insn_transform, unable to generate reloads for xor, since r14-2447-g13c556d6ae84be

[crazylht at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111225

--- Comment #1 from Hongtao.liu  ---
So reload thought CT_SPECIAL_MEMORY is always win for spilled_pesudo_p, but
here Br should be a vec_dup:mem which doesn't match spilled_pseduo_p.

case CT_SPECIAL_MEMORY:
  if (satisfies_memory_constraint_p (op, cn))
win = true;
  else if (spilled_pseudo_p (op))
win = true;
  break;