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

[jiawei <jiawei@iscas.ac.cn>]

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"
+  "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) 
+		? 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