arcv: introduce and incorporate the --param=arcv-mpy-option flag

This commit adds the new arcv-mpy-option compilation parameter with the valid
(string) values of 1c, 2c, and 10c.  This corresponds to different versions of
the MPY/DIV unit of the RMX100 core, each of which has different latencies for
imul/idiv instructions.

Internally, this option is propagated to the pipeline description information
in rmx100.md with the use of new helper functions defined in riscv.cc.

Signed-off-by: Artemiy Volkov <artemiy@synopsys.com>

Author: artemiy-volkov

gcc/config/riscv/arcv-rmx100.md

@@ -67,11 +67,6 @@
        (eq_attr "type" "fadd,fmul,fmadd,fcmp"))
   "arcv_rmx100_FPU*2")
 
-(define_insn_reservation "arcv_rmx100_fdiv_insn" 17
-  (and (eq_attr "tune" "arcv_rmx100")
-       (eq_attr "type" "fdiv,fsqrt"))
-  "arcv_rmx100_FPU*17")
-
 (define_insn_reservation "arcv_rmx100_xfer" 2
   (and (eq_attr "tune" "arcv_rmx100")
        (eq_attr "type" "fmove,mtc,mfc,fcvt,fcvt_f2i,fcvt_i2f"))
@@ -108,3 +103,9 @@
   (and (eq_attr "tune" "arcv_rmx100")
        (eq_attr "type" "fsqrt"))
   "arcv_rmx100_FPU*25")
+
+(define_bypass 1 "arcv_rmx100_mpy32_insn" "arcv_rmx100_*" "arcv_mpy_1c_bypass_p")
+(define_bypass 2 "arcv_rmx100_mpy32_insn" "arcv_rmx100_*" "arcv_mpy_2c_bypass_p")
+
+(define_bypass 9 "arcv_rmx100_div_insn" "arcv_rmx100_*" "arcv_mpy_1c_bypass_p")
+(define_bypass 9 "arcv_rmx100_div_insn" "arcv_rmx100_*" "arcv_mpy_2c_bypass_p")

gcc/config/riscv/riscv-opts.h

@@ -86,6 +86,13 @@ enum rvv_max_lmul_enum {
   RVV_DYNAMIC = 9
 };
 
+/* ARC-V multiply option.  */
+enum arcv_mpy_option_enum {
+  ARCV_MPY_OPTION_1C = 1,
+  ARCV_MPY_OPTION_2C = 2,
+  ARCV_MPY_OPTION_10C = 8,
+};
+
 enum riscv_multilib_select_kind {
   /* Select multilib by builtin way.  */
   select_by_builtin,

gcc/config/riscv/riscv-protos.h

@@ -165,6 +165,9 @@ extern bool riscv_epilogue_uses (unsigned int);
 extern bool riscv_can_use_return_insn (void);
 extern rtx riscv_function_value (const_tree, const_tree, enum machine_mode);
 extern bool riscv_store_data_bypass_p (rtx_insn *, rtx_insn *);
+extern bool arcv_mpy_1c_bypass_p (rtx_insn *, rtx_insn *);
+extern bool arcv_mpy_2c_bypass_p (rtx_insn *, rtx_insn *);
+extern bool arcv_mpy_10c_bypass_p (rtx_insn *, rtx_insn *);
 extern rtx riscv_gen_gpr_save_insn (struct riscv_frame_info *);
 extern bool riscv_gpr_save_operation_p (rtx);
 extern void riscv_reinit (void);

gcc/config/riscv/riscv.cc

@@ -10490,6 +10490,30 @@ riscv_store_data_bypass_p (rtx_insn *out_insn, rtx_insn *in_insn)
   return store_data_bypass_p (out_insn, in_insn);
 }
 
+/* Implement one boolean function for each of the values of the
+   arcv_mpy_option enum, for the needs of rhx100.md.  */
+
+bool
+arcv_mpy_1c_bypass_p (rtx_insn *out_insn ATTRIBUTE_UNUSED,
+		       rtx_insn *in_insn ATTRIBUTE_UNUSED)
+{
+  return arcv_mpy_option == ARCV_MPY_OPTION_1C;
+}
+
+bool
+arcv_mpy_2c_bypass_p (rtx_insn *out_insn ATTRIBUTE_UNUSED,
+		       rtx_insn *in_insn ATTRIBUTE_UNUSED)
+{
+  return arcv_mpy_option == ARCV_MPY_OPTION_2C;
+}
+
+bool
+arcv_mpy_10c_bypass_p (rtx_insn *out_insn ATTRIBUTE_UNUSED,
+			rtx_insn *in_insn ATTRIBUTE_UNUSED)
+{
+  return arcv_mpy_option == ARCV_MPY_OPTION_10C;
+}
+
 /* Implement TARGET_SECONDARY_MEMORY_NEEDED.
 
    When floating-point registers are wider than integer ones, moves between

gcc/config/riscv/riscv.opt

@@ -396,3 +396,20 @@ Specifies whether the fence.tso instruction should be used.
 mautovec-segment
 Target Integer Var(riscv_mautovec_segment) Init(1)
 Enable (default) or disable generation of vector segment load/store instructions.
+
+Enum
+Name(arcv_mpy_option) Type(enum arcv_mpy_option_enum)
+Valid arguments to -param=arcv_mpy_option=:
+
+EnumValue
+Enum(arcv_mpy_option) String(1c) Value(ARCV_MPY_OPTION_1C)
+
+EnumValue
+Enum(arcv_mpy_option) String(2c) Value(ARCV_MPY_OPTION_2C)
+
+EnumValue
+Enum(arcv_mpy_option) String(10c) Value(ARCV_MPY_OPTION_10C)
+
+-param=arcv-mpy-option=
+Target RejectNegative Joined Enum(arcv_mpy_option) Var(arcv_mpy_option) Init(ARCV_MPY_OPTION_2C)
+The type of MPY unit used by the RMX-100 core (to be used in combination with -mtune=rmx100) (default: 2c).