[Bug target/104868] [12 Regression] powerpc: Compiling libgfortran with -flto failing with GCC 12

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104868

--- Comment #10 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Michael Meissner <meissner@gcc.gnu.org>:

https://gcc.gnu.org/g:3cb27b85a7b977958d53e1a29596ba211d21dde2

commit r12-7620-g3cb27b85a7b977958d53e1a29596ba211d21dde2
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Fri Mar 11 19:47:09 2022 -0500

    Fix DImode to TImode sign extend issue

    PR target/104868 had had an issue where my code that updated the DImode to
    TImode sign extension for power10 failed.  In looking at the failure
    message, the reason is when extendditi2 tries to split the insn, it
    generates an insn that does not satisfy its constraints:

            (set (reg:V2DI 65 1)
                 (vec_duplicate:V2DI (reg:DI 0)))

    The reason is vsx_splat_v2di does not allow GPR register 0 when the will
    be generating a mtvsrdd instruction.  In the definition of the mtvsrdd
    instruction, if the RA register is 0, it means clear the upper 64 bits of
    the vector instead of moving register GPR 0 to those bits.

    When I wrote the extendditi2 pattern, I forgot that mtvsrdd had that
    behavior so I used a 'r' constraint instead of 'b'.  In the rare case
    where the value is in GPR register 0, this split will fail.

    This patch uses the right constraint for extendditi2.

    2022-03-11   Michael Meissner  <meissner@linux.ibm.com>

    gcc/
            PR target/104868
            * config/rs6000/vsx.md (extendditi2): Use a 'b' constraint when
            moving from a GPR register to an Altivec register.