[Bug target/97252] [10 Regression] arm: ICE compiling pure-code/pr94538-2.c with MVE since r10-7293-g3eff57aa

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97252

--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Alex Coplan
<acoplan@gcc.gnu.org>:

https://gcc.gnu.org/g:f14adc64c1be6e6a07689ef87c65fc87cc24902f

commit r10-9555-gf14adc64c1be6e6a07689ef87c65fc87cc24902f
Author: Alex Coplan <alex.coplan@arm.com>
Date:   Mon Mar 22 14:43:15 2021 +0000

    arm: Fix MVE ICEs with vector moves and -mpure-code [PR97252]

    This fixes around 500 ICEs in the testsuite which can be seen when
    testing with -march=armv8.1-m.main+mve -mfloat-abi=hard -mpure-code
    (leaving the testsuite free of ICEs in this configuration). All of the
    ICEs are in arm_print_operand (which is expecting a mem and gets another
    rtx, e.g. a const_vector) when running the output code for
    *mve_mov<mode> in alternative 4.

    The issue is that MVE vector moves were relying on the arm_reorg pass to
    move constant vectors that we can't easily synthesize to the literal
    pool. This doesn't work for -mpure-code where the literal pool is
    disabled. LLVM puts these in .rodata: I've chosen to do the same here.

    With this change, for -mpure-code, we no longer want to allow a constant
    on the RHS of a vector load in RA. To achieve this, I added a new
    constraint which matches constants only if the literal pool is
    available.

    gcc/ChangeLog:

            PR target/97252
            * config/arm/arm-protos.h (neon_make_constant): Add generate
            argument to guard emitting insns, default to true.
            * config/arm/arm.c (arm_legitimate_constant_p_1): Reject
            CONST_VECTORs which neon_make_constant can't handle.
            (neon_vdup_constant): Add generate argument, avoid emitting
            insns if it's not set.
            (neon_make_constant): Plumb new generate argument through.
            * config/arm/constraints.md (Ui): New. Use it...
            * config/arm/mve.md (*mve_mov<mode>): ... here.
            * config/arm/vec-common.md (movv8hf): Use neon_make_constant to
            synthesize constants.

    (cherry picked from commit 150a829accd76ddd73c20628774cb0781f6e8bfe)