arcv: adjust scheduling priority of memop pairs for RHX-100

This patch implements riscv_sched_adjust_priority () for the RHX-100
microarchitecture by slightly bumping the priority of load/store pairs.  As a
consequence of this change, it becomes easier for riscv_sched_reorder2 () to
schedule instructions in the memory pipe.

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

Author: artemiy-volkov

gcc/config/riscv/riscv.cc

@@ -11520,6 +11520,31 @@ riscv_sched_can_speculate_insn (rtx_insn *insn)
     }
 }
 
+static int
+riscv_sched_adjust_priority (rtx_insn *insn, int priority)
+{
+  if (!riscv_is_micro_arch (arcv_rhx100))
+    return priority;
+
+  if (DEBUG_INSN_P (insn) || GET_CODE (PATTERN (insn)) == USE
+      || GET_CODE (PATTERN (insn)) == CLOBBER)
+    return priority;
+
+  /* Bump the priority of fused load-store pairs for easier
+     scheduling of the memory pipe.  The specific increase
+     value is determined empirically.  */
+  if (next_insn (insn) && INSN_P (next_insn (insn))
+      && SCHED_GROUP_P (next_insn (insn))
+      && ((get_attr_type (insn) == TYPE_STORE
+	   && get_attr_type (next_insn (insn)) == TYPE_STORE)
+	 || (get_attr_type (insn) == TYPE_LOAD
+	     && get_attr_type (next_insn (insn)) == TYPE_LOAD)))
+    return priority + 1;
+
+  return priority;
+}
+
+
 static void
 riscv_sched_init (FILE *file ATTRIBUTE_UNUSED,
 		  int verbose ATTRIBUTE_UNUSED,
@@ -16248,10 +16273,12 @@ riscv_prefetch_offset_address_p (rtx x, machine_mode mode)
 #undef  TARGET_SCHED_ADJUST_COST
 #define TARGET_SCHED_ADJUST_COST riscv_sched_adjust_cost
 
-
 #undef TARGET_SCHED_CAN_SPECULATE_INSN
 #define TARGET_SCHED_CAN_SPECULATE_INSN riscv_sched_can_speculate_insn
 
+#undef  TARGET_SCHED_ADJUST_PRIORITY
+#define TARGET_SCHED_ADJUST_PRIORITY riscv_sched_adjust_priority
+
 #undef  TARGET_SCHED_REORDER2
 #define TARGET_SCHED_REORDER2 riscv_sched_reorder2