[Bug target/110109] RISC-V: ICE when build the Intrinsic code

[cvs-commit at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110109

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

https://gcc.gnu.org/g:a96ba6b958a00ad59c43cae10be65b263b5d0d2d

commit r14-1531-ga96ba6b958a00ad59c43cae10be65b263b5d0d2d
Author: Juzhe-Zhong <juzhe.zh...@rivai.ai>
Date:   Sun Jun 4 16:51:47 2023 +0800

    RISC-V: Remove redundant vlmul_ext_* patterns to fix PR110109

    This patch is to fix PR110109 issue. This issue happens is because:

    (define_insn_and_split "*vlmul_extx2<mode>"
      [(set (match_operand:<VLMULX2> 0 "register_operand"  "=vr, ?&vr")
           (subreg:<VLMULX2>
             (match_operand:VLMULEXT2 1 "register_operand" " 0,   vr") 0))]
      "TARGET_VECTOR"
      "#"
      "&& reload_completed"
      [(const_int 0)]
    {
      emit_insn (gen_rtx_SET (gen_lowpart (<MODE>mode, operands[0]),
operands[1]));
      DONE;
    })

    Such pattern generate such codes in insn-recog.cc:
    static int
    pattern57 (rtx x1)
    {
      rtx * const operands ATTRIBUTE_UNUSED = &recog_data.operand[0];
      rtx x2;
      int res ATTRIBUTE_UNUSED;
      if (maybe_ne (SUBREG_BYTE (x1).to_constant (), 0))
        return -1;
    ...

    PR110109 ICE at maybe_ne (SUBREG_BYTE (x1).to_constant (), 0) since for
scalable
    RVV modes can not be accessed as SUBREG_BYTE (x1).to_constant ()

    I create that patterns is to optimize the following test:
    vfloat32m2_t test_vlmul_ext_v_f32mf2_f32m2(vfloat32mf2_t op1) {
      return __riscv_vlmul_ext_v_f32mf2_f32m2(op1);
    }

    codegen:
    test_vlmul_ext_v_f32mf2_f32m2:
            vsetvli a5,zero,e32,m2,ta,ma
            vmv.v.i v2,0
            vsetvli a5,zero,e32,mf2,ta,ma
            vle32.v v2,0(a1)
            vs2r.v  v2,0(a0)
            ret

    There is a redundant 'vmv.v.i' here, Since GCC doesn't undefine IR
    (unlike LLVM, LLVM has undef/poison).  For vlmul_ext_* RVV intrinsic,
    GCC will initiate all zeros into register. However, I think it's not
    a big issue after we support subreg livness tracking.

            PR target/110109

    gcc/ChangeLog:

            * config/riscv/riscv-vector-builtins-bases.cc: Change expand
approach.
            * config/riscv/vector.md (@vlmul_extx2<mode>): Remove it.
            (@vlmul_extx4<mode>): Ditto.
            (@vlmul_extx8<mode>): Ditto.
            (@vlmul_extx16<mode>): Ditto.
            (@vlmul_extx32<mode>): Ditto.
            (@vlmul_extx64<mode>): Ditto.
            (*vlmul_extx2<mode>): Ditto.
            (*vlmul_extx4<mode>): Ditto.
            (*vlmul_extx8<mode>): Ditto.
            (*vlmul_extx16<mode>): Ditto.
            (*vlmul_extx32<mode>): Ditto.
            (*vlmul_extx64<mode>): Ditto.

    gcc/testsuite/ChangeLog:

            * gcc.target/riscv/rvv/base/pr110109-1.c: New test.
            * gcc.target/riscv/rvv/base/pr110109-2.c: New test.