[Bug target/114639] [riscv] ICE in create_pre_exit, at mode-switching.cc:451

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114639

--- Comment #14 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Pan Li <panli@gcc.gnu.org>:

https://gcc.gnu.org/g:e40a3d86511efcea71e9eadde8fb9f96be52f790

commit r14-9908-ge40a3d86511efcea71e9eadde8fb9f96be52f790
Author: Pan Li <pan2.li@intel.com>
Date:   Thu Apr 11 09:39:44 2024 +0800

    RISC-V: Bugfix ICE for the vector return arg in mode switch

    This patch would like to fix a ICE in mode sw for below example code.

    during RTL pass: mode_sw
    test.c: In function âvbool16_t j(vuint64m4_t)â:
    test.c:15:1: internal compiler error: in create_pre_exit, at
    mode-switching.cc:451
       15 | }
          | ^
    0x3978f12 create_pre_exit
            __RISCV_BUILD__/../gcc/mode-switching.cc:451
    0x3979e9e optimize_mode_switching
            __RISCV_BUILD__/../gcc/mode-switching.cc:849
    0x397b9bc execute
            __RISCV_BUILD__/../gcc/mode-switching.cc:1324

    extern size_t get_vl ();

    vbool16_t
    test (vuint64m4_t a)
    {
      unsigned long b;
      return __riscv_vmsne_vx_u64m4_b16 (a, b, get_vl ());
    }

    The create_pre_exit would like to find a return value copy.  If
    not, there will be a reason in assert but not available for above
    sample code when vector calling convension is enabled by default.
    This patch would like to override the TARGET_FUNCTION_VALUE_REGNO_P
    for vector register and then we will have hard_regno_nregs for copy_num,
    aka there is a return value copy.

    As a side-effect of allow vector in TARGET_FUNCTION_VALUE_REGNO_P, the
    TARGET_GET_RAW_RESULT_MODE will have vector mode and which is sizeless
    cannot be converted to fixed_size_mode.  Thus override the hook
    TARGET_GET_RAW_RESULT_MODE and return VOIDmode when the regno is-not-a
    fixed_size_mode.

    The below tests are passed for this patch.
    * The fully riscv regression tests.
    * The reproducing test in bugzilla PR114639.

            PR target/114639

    gcc/ChangeLog:

            * config/riscv/riscv.cc (riscv_function_value_regno_p): New func
            impl for hook TARGET_FUNCTION_VALUE_REGNO_P.
            (riscv_get_raw_result_mode): New func imple for hook
            TARGET_GET_RAW_RESULT_MODE.
            (TARGET_FUNCTION_VALUE_REGNO_P): Impl the hook.
            (TARGET_GET_RAW_RESULT_MODE): Ditto.
            * config/riscv/riscv.h (V_RETURN): New macro for vector return.
            (GP_RETURN_FIRST): New macro for the first GPR in return.
            (GP_RETURN_LAST): New macro for the last GPR in return.
            (FP_RETURN_FIRST): Diito but for FPR.
            (FP_RETURN_LAST): Ditto.
            (FUNCTION_VALUE_REGNO_P): Remove as deprecated and replace by
            TARGET_FUNCTION_VALUE_REGNO_P.

    gcc/testsuite/ChangeLog:

            * g++.target/riscv/rvv/base/pr114639-1.C: New test.
            * gcc.target/riscv/rvv/base/pr114639-1.c: New test.

    Signed-off-by: Pan Li <pan2.li@intel.com>