[PATCH] RISC-V: Fix missing boolean_expression in zmmul extension

[PATCH] RISC-V: Fix missing boolean_expression in zmmul extension

[Liao Shihua]

Missing boolean_expression TARGET_ZMMUL in riscv_rtx_costs() casuse different instructions when multiplying an integer with a constant.
( https://github.com/riscv-collab/riscv-gnu-toolchain/issues/1482 )

int foo(int *ib) {
    *ib = *ib * 33938;
    return 0;
}

rv64im:
        lw      a4,0(a1)
        li      a5,32768
        addiw   a5,a5,1170
        mulw    a5,a5,a4
        sw      a5,0(a1)
        ret

rv64i_zmmul:
        lw      a4,0(a1)
        slliw   a5,a4,5
        addw    a5,a5,a4
        slliw   a5,a5,3
        addw    a5,a5,a4
        slliw   a5,a5,3
        addw    a5,a5,a4
        slliw   a5,a5,3
        addw    a5,a5,a4
        slliw   a5,a5,1
        sw      a5,0(a1)
        ret

Fixed.

gcc/ChangeLog:

        * config/riscv/riscv.cc (riscv_rtx_costs): Add TARGET_ZMMUL.

---
 gcc/config/riscv/riscv.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 85df5b7ab49..580ae007181 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -3753,7 +3753,7 @@ riscv_rtx_costs (rtx x, machine_mode mode, int outer_code, int opno ATTRIBUTE_UN
     case MULT:
       if (float_mode_p)
 	*total = tune_param->fp_mul[mode == DFmode];
-      else if (!TARGET_MUL)
+      else if (!(TARGET_MUL || TARGET_ZMMUL))
 	/* Estimate the cost of a library call.  */
 	*total = COSTS_N_INSNS (speed ? 32 : 6);
       else if (GET_MODE_SIZE (mode).to_constant () > UNITS_PER_WORD)
-- 
2.34.1

Re: [PATCH] RISC-V: Fix missing boolean_expression in zmmul extension

[Kito Cheng]

[-- Attachment #1: Type: text/plain, Size: 1838 bytes --]

Could you add a testcase to make sure zmmul will generate mul instruction?

Liao Shihua <shihua@iscas.ac.cn> 於 2024年5月23日 週四 18:48 寫道：

> Missing boolean_expression TARGET_ZMMUL in riscv_rtx_costs() casuse
> different instructions when multiplying an integer with a constant.
> ( https://github.com/riscv-collab/riscv-gnu-toolchain/issues/1482 )
>
> int foo(int *ib) {
>     *ib = *ib * 33938;
>     return 0;
> }
>
> rv64im:
>         lw      a4,0(a1)
>         li      a5,32768
>         addiw   a5,a5,1170
>         mulw    a5,a5,a4
>         sw      a5,0(a1)
>         ret
>
> rv64i_zmmul:
>         lw      a4,0(a1)
>         slliw   a5,a4,5
>         addw    a5,a5,a4
>         slliw   a5,a5,3
>         addw    a5,a5,a4
>         slliw   a5,a5,3
>         addw    a5,a5,a4
>         slliw   a5,a5,3
>         addw    a5,a5,a4
>         slliw   a5,a5,1
>         sw      a5,0(a1)
>         ret
>
> Fixed.
>
> gcc/ChangeLog:
>
>         * config/riscv/riscv.cc (riscv_rtx_costs): Add TARGET_ZMMUL.
>
> ---
>  gcc/config/riscv/riscv.cc | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
> index 85df5b7ab49..580ae007181 100644
> --- a/gcc/config/riscv/riscv.cc
> +++ b/gcc/config/riscv/riscv.cc
> @@ -3753,7 +3753,7 @@ riscv_rtx_costs (rtx x, machine_mode mode, int
> outer_code, int opno ATTRIBUTE_UN
>      case MULT:
>        if (float_mode_p)
>         *total = tune_param->fp_mul[mode == DFmode];
> -      else if (!TARGET_MUL)
> +      else if (!(TARGET_MUL || TARGET_ZMMUL))
>         /* Estimate the cost of a library call.  */
>         *total = COSTS_N_INSNS (speed ? 32 : 6);
>        else if (GET_MODE_SIZE (mode).to_constant () > UNITS_PER_WORD)
> --
> 2.34.1
>
>