8349764: RISC-V: C1: Improve Class.isInstance intrinsic

Reviewed-by: fyang, mli

Author: zifeihan

src/hotspot/cpu/riscv/c1_LIRGenerator_riscv.cpp

@@ -1104,7 +1104,7 @@ void LIRGenerator::do_InstanceOf(InstanceOf* x) {
 
 // Intrinsic for Class::isInstance
 address LIRGenerator::isInstance_entry() {
-  return CAST_FROM_FN_PTR(address, Runtime1::is_instance_of);
+  return Runtime1::entry_for(C1StubId::is_instance_of_id);
 }
 
 void LIRGenerator::do_If(If* x) {

src/hotspot/cpu/riscv/c1_Runtime1_riscv.cpp

@@ -925,6 +925,52 @@ OopMapSet* Runtime1::generate_code_for(C1StubId id, StubAssembler* sasm) {
       }
       break;
 
+    case C1StubId::is_instance_of_id:
+      {
+        // Mirror: x10
+        // Object: x11
+        // Temps: x13, x14, x15, x16, x17
+        // Result: x10
+
+        // Get the Klass* into x16
+        Register klass = x16, obj = x11, result = x10;
+        __ ld(klass, Address(x10, java_lang_Class::klass_offset()));
+
+        Label fail, is_secondary, success;
+
+        __ beqz(klass, fail); // Klass is null
+        __ beqz(obj, fail); // obj is null
+
+        __ lwu(x13, Address(klass, in_bytes(Klass::super_check_offset_offset())));
+        __ mv(x17, in_bytes(Klass::secondary_super_cache_offset()));
+        __ beq(x13, x17, is_secondary); // Klass is a secondary superclass
+
+        // Klass is a concrete class
+        __ load_klass(x15, obj);
+        __ add(x17, x15, x13);
+        __ ld(x17, Address(x17));
+        __ beq(klass, x17, success);
+        __ mv(result, 0);
+        __ ret();
+
+        __ bind(is_secondary);
+        __ load_klass(obj, obj);
+
+        // This is necessary because I am never in my own secondary_super list.
+        __ beq(obj, klass, success);
+
+        __ lookup_secondary_supers_table_var(obj, klass, result, x13, x14, x15, x17, &success);
+
+        __ bind(fail);
+        __ mv(result, 0);
+        __ ret();
+
+        __ bind(success);
+        __ mv(result, 1);
+        __ ret();
+      }
+      break;
+
     case C1StubId::monitorexit_nofpu_id:
       save_fpu_registers = false;
       // fall through