[Bug target/112599] RISC-V regression testsuite errors with rv64gcv_zvl1024b

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112599

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Robin Dapp <rdapp@gcc.gnu.org>:

https://gcc.gnu.org/g:35a688f434159a923420310860c5bc721e29a741

commit r14-5777-g35a688f434159a923420310860c5bc721e29a741
Author: Juzhe-Zhong <juzhe.zhong@rivai.ai>
Date:   Thu Nov 23 19:59:52 2023 +0800

    RISC-V: Disable AVL propagation of vrgather instruction

    This patch fixes following FAILs in zvl1024b of both RV32/RV64:

    FAIL: gcc.c-torture/execute/990128-1.c   -O2  execution test
    FAIL: gcc.c-torture/execute/990128-1.c   -O2 -flto -fno-use-linker-plugin
-flto-partition=none  execution test
    FAIL: gcc.c-torture/execute/990128-1.c   -O2 -flto -fuse-linker-plugin
-fno-fat-lto-objects  execution test
    FAIL: gcc.c-torture/execute/990128-1.c   -O3 -fomit-frame-pointer
-funroll-loops -fpeel-loops -ftracer -finline-functions  execution test
    FAIL: gcc.c-torture/execute/990128-1.c   -O3 -g  execution test
    FAIL: gcc.dg/torture/pr58955-2.c   -O3 -fomit-frame-pointer -funroll-loops
-fpeel-loops -ftracer -finline-functions  execution test

    The root case can be simpliy described in this following small case:

    https://godbolt.org/z/7GaxbEGzG

    typedef int64_t v1024b __attribute__ ((vector_size (128)));

    void foo (void *out, void *in, int64_t a, int64_t b)
    {
      v1024b v = {a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,a};
      v1024b v2 = {b,b,b,b,b,b,b,b,b,b,b,b,b,b,b,b};
      v1024b index = *(v1024b*)in;
      v1024b v3 = __builtin_shuffle (v, v2, index);
      __riscv_vse64_v_i64m1 (out, (vint64m1_t)v3, 10);
    }

    Incorrect ASM:

    foo:
            li      a5,31
            vsetivli        zero,10,e64,m1,ta,mu
            vmv.v.x v2,a5
            vl1re64.v       v1,0(a1)
            vmv.v.x v4,a2
            vand.vv v1,v1,v2
            vmv.v.x v3,a3
            vmsgeu.vi       v0,v1,16
            vrgather.vv     v2,v4,v1       --> AVL = VLMAX according to codes.
            vadd.vi v1,v1,-16
            vrgather.vv     v2,v3,v1,v0.t  --> AVL = VLMAX according to codes.
            vse64.v v2,0(a0)               --> AVL = 10 according to codes.
            ret

    For vrgather dest, source, index instruction, when index may has the value
> the following store AVL
    that is index value > 10.  In this situation, the codes above will end up
with:

    The source vector of vrgather has undefined value on index >= AVL (which is
10 in this case).

    So disable AVL propagation for vrgather instruction.

            PR target/112599
            PR target/112670

    gcc/ChangeLog:

            * config/riscv/riscv-avlprop.cc (alv_can_be_propagated_p): New
function.
            (vlmax_ta_p): Disable vrgather AVL propagation.

    gcc/testsuite/ChangeLog:

            * gcc.target/riscv/rvv/autovec/pr112599-1.c: New test.