[Bug rtl-optimization/112278] New: lra: ICE in partial_subreg_p for mixture of AdvSIMD & SVE register asms

[Bug rtl-optimization/112278] New: lra: ICE in partial_subreg_p for mixture of AdvSIMD & SVE register asms

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112278

            Bug ID: 112278
           Summary: lra: ICE in partial_subreg_p for mixture of AdvSIMD &
                    SVE register asms
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rsandifo at gcc dot gnu.org
  Target Milestone: ---

The following test, compiled with -march=armv8.2-a+sve, ICEs in
partial_subreg_p, called from new_insn_reg:

#include <arm_neon.h>
#include <arm_sve.h>

void
f (void)
{
  {
    register svint8_t v0 asm ("z0");
    asm volatile ("" : "=w" (v0));
  }
  {
    register int8x8x4_t v0 asm ("v0");
    asm volatile ("" : "=w" (v0));
  }
}

GCC 10 behaves similarly, so I don't think this is a regression.

[Bug rtl-optimization/112278] lra: ICE in partial_subreg_p for mixture of AdvSIMD & SVE register asms

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112278

Richard Sandiford <rsandifo at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2023-10-29
     Ever confirmed|0                           |1
           Assignee|unassigned at gcc dot gnu.org      |rsandifo at gcc dot gnu.org

--- Comment #1 from Richard Sandiford <rsandifo at gcc dot gnu.org> ---
Testing a patch.

[Bug rtl-optimization/112278] lra: ICE in partial_subreg_p for mixture of AdvSIMD & SVE register asms

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112278

--- Comment #2 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Richard Sandiford <rsandifo@gcc.gnu.org>:

https://gcc.gnu.org/g:6e2e0ce6795c863e295eb33559f8dc0500297da3

commit r14-6139-g6e2e0ce6795c863e295eb33559f8dc0500297da3
Author: Richard Sandiford <richard.sandiford@arm.com>
Date:   Tue Dec 5 09:20:55 2023 +0000

    lra: Updates of biggest mode for hard regs [PR112278]

    LRA keeps track of the biggest mode for both hard registers and
    pseudos.  The updates assume that the modes are ordered, i.e. that
    we can tell whether one is no bigger than the other at compile time.

    That is (or at least seemed to be) a reasonable restriction for pseudos.
    But it isn't necessarily so for hard registers, since the uses of hard
    registers can be logically distinct.  The testcase is an example of this.

    The biggest mode of hard registers is also special for other reasons.
    As the existing comment says:

      /* A reg can have a biggest_mode of VOIDmode if it was only ever seen as
         part of a multi-word register.  In that case, just use the reg_rtx
         mode.  Do the same also if the biggest mode was larger than a register
         or we can not compare the modes.  Otherwise, limit the size to that of
         the biggest access in the function or to the natural mode at least. 
*/

    This patch applies the same approach to the updates.

    gcc/
            PR rtl-optimization/112278
            * lra-int.h (lra_update_biggest_mode): New function.
            * lra-coalesce.cc (merge_pseudos): Use it.
            * lra-lives.cc (process_bb_lives): Likewise.
            * lra.cc (new_insn_reg): Likewise.

    gcc/testsuite/
            PR rtl-optimization/112278
            * gcc.target/aarch64/sve/pr112278.c: New test.

[Bug rtl-optimization/112278] lra: ICE in partial_subreg_p for mixture of AdvSIMD & SVE register asms

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112278

Richard Sandiford <rsandifo at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED

--- Comment #3 from Richard Sandiford <rsandifo at gcc dot gnu.org> ---
Fixed on trunk.