[Bug c/96682] Arm: Wrong code generated for MVE with -O1 and above optimization options.

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96682

--- Comment #1 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Joe Ramsay
<joeramsay@gcc.gnu.org>:

https://gcc.gnu.org/g:10e0d2010f0597e6ae7efb88142b8820608c585e

commit r10-8643-g10e0d2010f0597e6ae7efb88142b8820608c585e
Author: Joe Ramsay <joe.ramsay@arm.com>
Date:   Wed Jul 29 14:04:28 2020 +0100

    arm: Enable no-writeback vldr.16/vstr.16.

    There was previously no way to specify that a register operand cannot
    have any writeback modifiers, and as a result the argument to vldr.16
    and vstr.16 could be erroneously output with post-increment. This
    change adds a constraint which forbids all writeback, and
    selects it in the relevant case for vldr.16 and vstr.16

    gcc/ChangeLog:

            PR target/96682
            * config/arm/arm-protos.h (arm_coproc_mem_operand_no_writeback):
            Declare prototype.
            (arm_mve_mode_and_operands_type_check): Declare prototype.
            * config/arm/arm.c (arm_coproc_mem_operand): Refactor to use
            _arm_coproc_mem_operand.
            (arm_coproc_mem_operand_wb): New function to cover full, limited
            and no writeback.
            (arm_coproc_mem_operand_no_writeback): New constraint for memory
            operand with no writeback.
            (arm_print_operand): Extend 'E' specifier for memory operand
            that does not support writeback.
            (arm_mve_mode_and_operands_type_check): New constraint check for
            MVE memory operands.
            * config/arm/constraints.md: Add Uj constraint for VFP vldr.16
            and vstr.16.
            * config/arm/vfp.md (*mov_load_vfp_hf16): New pattern for
            vldr.16.
            (*mov_store_vfp_hf16): New pattern for vstr.16.
            (*mov<mode>_vfp_<mode>16): Remove MVE moves.

    gcc/testsuite/ChangeLog:

            PR target/96682
            * gcc.target/arm/mve/intrinsics/mve-vldstr16-no-writeback.c: New
test.

    (cherry picked from commit 9f6abd2db90151c8966d2d2718ab8c299abf1105)