[v4,3/4] RISC-V: Limit regs use for z*inx extension.

  From: Jiawei <jiawei@iscas.ac.cn>

Limit z*inx abi support with 'ilp32','ilp32e','lp64' only.
Use GPR instead FPR when 'zfinx' enable, Only use even registers 
in RV32 when 'zdinx' enable.
Enable FLOAT16 when Zhinx/Zhinxmin enabled.

Co-Authored-By: Sinan Lin.

gcc/ChangeLog:

        * config/riscv/constraints.md (TARGET_ZFINX ? GR_REGS): Set GPRS
          use while Zfinx is enable.
        * config/riscv/riscv.cc (riscv_hard_regno_mode_ok): Limit odd
          registers use when Zdinx enable in RV32 cases.
        (riscv_option_override): New target enable MASK_FDIV.
        (riscv_libgcc_floating_mode_supported_p): New error info when
	  use incompatible arch&abi.
        (riscv_excess_precision): New target enable FLOAT16.

---
 gcc/config/riscv/constraints.md |  5 +++--
 gcc/config/riscv/riscv.cc       | 21 +++++++++++++++++----
 2 files changed, 20 insertions(+), 6 deletions(-)
  

Hmmm 2 issue, but I fixed that anyway, otherwise LGTM.

> From: Jiawei <jiawei@iscas.ac.cn>
>
> Limit z*inx abi support with 'ilp32','ilp32e','lp64' only.
> Use GPR instead FPR when 'zfinx' enable, Only use even registers
> in RV32 when 'zdinx' enable.
> Enable FLOAT16 when Zhinx/Zhinxmin enabled.
>
> Co-Authored-By: Sinan Lin.
>
> gcc/ChangeLog:
>
>         * config/riscv/constraints.md (TARGET_ZFINX ? GR_REGS): Set GPRS
>           use while Zfinx is enable.
>         * config/riscv/riscv.cc (riscv_hard_regno_mode_ok): Limit odd
>           registers use when Zdinx enable in RV32 cases.
>         (riscv_option_override): New target enable MASK_FDIV.
>         (riscv_libgcc_floating_mode_supported_p): New error info when
>           use incompatible arch&abi.
>         (riscv_excess_precision): New target enable FLOAT16.
>
> ---
>  gcc/config/riscv/constraints.md |  5 +++--
>  gcc/config/riscv/riscv.cc       | 21 +++++++++++++++++----
>  2 files changed, 20 insertions(+), 6 deletions(-)
>
> diff --git a/gcc/config/riscv/constraints.md b/gcc/config/riscv/constraints.md
> index 8997284f32e..c53e0f38920 100644
> --- a/gcc/config/riscv/constraints.md
> +++ b/gcc/config/riscv/constraints.md
> @@ -21,8 +21,9 @@
>
>  ;; Register constraints
>
> -(define_register_constraint "f" "TARGET_HARD_FLOAT ? FP_REGS : NO_REGS"
> -  "A floating-point register (if available).")
> +(define_register_constraint "f" "TARGET_HARD_FLOAT ? FP_REGS :
> +  (TARGET_ZFINX ? GR_REGS) : NO_REGS"

(TARGET_ZFINX ? GR_REGS : NO_REGS)"

> +  "A floating-point register (if available, reuse GPR as FPR when use zfinx).")
>
>  (define_register_constraint "j" "SIBCALL_REGS"
>    "@internal")
> diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
> index ad57b995e7b..38631605b2c 100644
> --- a/gcc/config/riscv/riscv.cc
> +++ b/gcc/config/riscv/riscv.cc
> @@ -5356,6 +5356,13 @@ riscv_hard_regno_mode_ok (unsigned int regno, machine_mode mode)
>         != call_used_or_fixed_reg_p (regno + i))
>        return false;
>
> +  /* Only use even registers in RV32 ZDINX */
> +  if (!TARGET_64BIT && TARGET_ZDINX){
> +    if (GET_MODE_CLASS (mode) == MODE_FLOAT &&
> +     GET_MODE_UNIT_SIZE (mode) == GET_MODE_SIZE (DFmode))
> +    return !(regno & 1);
> +  }
> +
>    return true;
>  }
>
> @@ -5595,7 +5602,7 @@ riscv_option_override (void)
>      error ("%<-mdiv%> requires %<-march%> to subsume the %<M%> extension");
>
>    /* Likewise floating-point division and square root.  */
> -  if (TARGET_HARD_FLOAT && (target_flags_explicit & MASK_FDIV) == 0)
> +  if ((TARGET_HARD_FLOAT || TARGET_ZFINX) && (target_flags_explicit & MASK_FDIV) == 0)
>      target_flags |= MASK_FDIV;
>
>    /* Handle -mtune, use -mcpu if -mtune is not given, and use default -mtune
> @@ -5641,6 +5648,11 @@ riscv_option_override (void)
>    if (TARGET_RVE && riscv_abi != ABI_ILP32E)
>      error ("rv32e requires ilp32e ABI");
>
> +  // Zfinx require abi ilp32,ilp32e or lp64.
> +  if (TARGET_ZFINX && riscv_abi != ABI_ILP32
> +      && riscv_abi != ABI_LP64 && riscv_abi != ABI_ILP32E)
> +    error ("z*inx requires ABI ilp32, ilp32e or lp64");
> +
>    /* We do not yet support ILP32 on RV64.  */
>    if (BITS_PER_WORD != POINTER_SIZE)
>      error ("ABI requires %<-march=rv%d%>", POINTER_SIZE);
> @@ -6273,7 +6285,7 @@ riscv_libgcc_floating_mode_supported_p (scalar_float_mode mode)
>         precision of the _FloatN type; evaluate all other operations and
>         constants to the range and precision of the semantic type;
>
> -   If we have the zfh extensions then we support _Float16 in native
> +   If we have the zfh/zhinx extensions then we support _Float16 in native
>     precision, so we should set this to 16.  */
>  static enum flt_eval_method
>  riscv_excess_precision (enum excess_precision_type type)
> @@ -6282,8 +6294,9 @@ riscv_excess_precision (enum excess_precision_type type)
>      {
>      case EXCESS_PRECISION_TYPE_FAST:
>      case EXCESS_PRECISION_TYPE_STANDARD:
> -      return (TARGET_ZFH ? FLT_EVAL_METHOD_PROMOTE_TO_FLOAT16
> -                        : FLT_EVAL_METHOD_PROMOTE_TO_FLOAT);
> +      return ((TARGET_ZFH || TARGET_ZHINX || TARGET_ZHINXMIN)

Should be (TARGET_ZFH || TARGET_ZHINX)


> +               ? FLT_EVAL_METHOD_PROMOTE_TO_FLOAT16
> +               : FLT_EVAL_METHOD_PROMOTE_TO_FLOAT);
>      case EXCESS_PRECISION_TYPE_IMPLICIT:
>      case EXCESS_PRECISION_TYPE_FLOAT16:
>        return FLT_EVAL_METHOD_PROMOTE_TO_FLOAT16;
> --
> 2.25.1
>