Re: [PATCH v1] RISC-V: Change the generation mode of ADJUST_SP_RTX from gen_insn to gen_SET.

[Kito Cheng <kito.cheng@gmail.com>]

Committed, thanks :)

On Fri, Feb 3, 2023 at 5:45 PM Jin Ma via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> The gen_insn method is used to generate ADJUST_SP_RTX here, which has certain
> potential risks:
>
> When the architecture adds pre-processing to `define_insn "adddi3"`, such as
> `define_expend "adddi3"`, the gen_expand will be automatically called here,
> causing the patern to emit directly, which will cause insn to enter REG_NOTE
> for `DWARF` instead of patern.
>
> The following error REG_NOTE occurred:
> error: invalid rtl sharing found in the insn:
> (insn 19 3 20 2 (parallel [
>         ...
>         ])
>     (expr_list:REG_CFA_ADJUST_CFA
>         (insn 18 0 0 (set (reg/f:DI 2 sp)
>             (plus:DI (reg/f:DI 2 sp)
>                 (const_int -16 [0xfffffffffffffff0]))) -1
>         (nil))))
>
> In fact, the correct one should be the following:
> (insn 19 3 20 2 (parallel [
>         ...
>         ])
>     (expr_list:REG_CFA_ADJUST_CFA
>         (set (reg/f:DI 2 sp)
>             (plus:DI (reg/f:DI 2 sp)
>                 (const_int -16 [0xfffffffffffffff0])))))
>
> Following the treatment of arm or other architectures, it is more reasonable to
> use gen_SET here.
>
> gcc/ChangeLog:
>
>         * config/riscv/riscv.cc (riscv_adjust_libcall_cfi_prologue): Change gen_add3_insn
>         to gen_rtx_SET.
>         (riscv_adjust_libcall_cfi_epilogue): Likewise.
> ---
>  gcc/config/riscv/riscv.cc | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
> index 3b7804b7501..c9c6e53c6d0 100644
> --- a/gcc/config/riscv/riscv.cc
> +++ b/gcc/config/riscv/riscv.cc
> @@ -5054,8 +5054,9 @@ riscv_adjust_libcall_cfi_prologue ()
>        }
>
>    /* Debug info for adjust sp.  */
> -  adjust_sp_rtx = gen_add3_insn (stack_pointer_rtx,
> -                                stack_pointer_rtx, GEN_INT (-saved_size));
> +  adjust_sp_rtx =
> +    gen_rtx_SET (stack_pointer_rtx,
> +                gen_rtx_PLUS (GET_MODE(stack_pointer_rtx), stack_pointer_rtx, GEN_INT (-saved_size)));
>    dwarf = alloc_reg_note (REG_CFA_ADJUST_CFA, adjust_sp_rtx,
>                           dwarf);
>    return dwarf;
> @@ -5176,8 +5177,9 @@ riscv_adjust_libcall_cfi_epilogue ()
>    int saved_size = cfun->machine->frame.save_libcall_adjustment;
>
>    /* Debug info for adjust sp.  */
> -  adjust_sp_rtx = gen_add3_insn (stack_pointer_rtx,
> -                                stack_pointer_rtx, GEN_INT (saved_size));
> +  adjust_sp_rtx =
> +    gen_rtx_SET (stack_pointer_rtx,
> +                gen_rtx_PLUS (GET_MODE(stack_pointer_rtx), stack_pointer_rtx, GEN_INT (saved_size)));
>    dwarf = alloc_reg_note (REG_CFA_ADJUST_CFA, adjust_sp_rtx,
>                           dwarf);
>
> --
> 2.17.1
>