[Bug target/97141] [10 Regression] aarch64, SVE: ICE in decompose, at rtl.h (during expand) since r10-4676-g9c437a108a

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97141

--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Richard Sandiford
<rsandifo@gcc.gnu.org>:

https://gcc.gnu.org/g:dc9233a4f65a67ca280903d60d57c5fd5d95303e

commit r10-9753-gdc9233a4f65a67ca280903d60d57c5fd5d95303e
Author: Richard Sandiford <richard.sandiford@arm.com>
Date:   Fri Apr 23 10:09:41 2021 +0100

    Handle CONST_POLY_INTs in CONST_VECTORs [PR97141, PR98726]

    This PR is caused by POLY_INT_CSTs being (necessarily) valid
    in tree-level VECTOR_CSTs but CONST_POLY_INTs not being valid
    in RTL CONST_VECTORs.  I can't tell/remember how deliberate
    that was, but I'm guessing not very.  In particular,
    valid_for_const_vector_p was added to guard against symbolic
    constants rather than CONST_POLY_INTs.

    I did briefly consider whether we should maintain the current
    status anyway.  However, that would then require a way of
    constructing variable-length vectors from individiual elements
    if, say, we have:

       { [2, 2], [3, 2], [4, 2], ⦠}

    So I'm chalking this up to an oversight.  I think the intention
    (and certainly the natural thing) is to have the same rules for
    both trees and RTL.

    The SVE CONST_VECTOR code should already be set up to handle
    CONST_POLY_INTs.  However, we need to add support for Advanced SIMD
    CONST_VECTORs that happen to contain SVE-based values.  The patch does
    that by expanding such CONST_VECTORs in the same way as variable vectors.

    gcc/
            PR rtl-optimization/97141
            PR rtl-optimization/98726
            * emit-rtl.c (valid_for_const_vector_p): Return true for
            CONST_POLY_INT_P.
            * rtx-vector-builder.h (rtx_vector_builder::step): Return a
            poly_wide_int instead of a wide_int.
            (rtx_vector_builder::apply_set): Take a poly_wide_int instead
            of a wide_int.
            * rtx-vector-builder.c (rtx_vector_builder::apply_set): Likewise.
            * config/aarch64/aarch64.c (aarch64_legitimate_constant_p): Return
            false for CONST_VECTORs that cannot be forced to memory.
            * config/aarch64/aarch64-simd.md (mov<mode>): If a CONST_VECTOR
            is too complex to force to memory, build it up from individual
            elements instead.

    gcc/testsuite/
            PR rtl-optimization/97141
            PR rtl-optimization/98726
            * gcc.c-torture/compile/pr97141.c: New test.
            * gcc.c-torture/compile/pr98726.c: Likewise.
            * gcc.target/aarch64/sve/pr97141.c: Likewise.
            * gcc.target/aarch64/sve/pr98726.c: Likewise.

    (cherry picked from commit 1b5f74e8be4dd7abe5624ff60adceff19ca71bda)