8343415: RISC-V: Increase maximum size of C2EntryBarrierStub by four

Reviewed-by: rehn, fjiang

Author: RealFYang

src/hotspot/cpu/riscv/c2_CodeStubs_riscv.cpp

@@ -55,14 +55,15 @@ void C2SafepointPollStub::emit(C2_MacroAssembler& masm) {
 
 int C2EntryBarrierStub::max_size() const {
   // 4 bytes for alignment
-  return 3 * NativeInstruction::instruction_size + 4 + 4;
+  return 4 * NativeInstruction::instruction_size + 4 + 4;
 }
 
 void C2EntryBarrierStub::emit(C2_MacroAssembler& masm) {
   __ bind(entry());
   // emits auipc + jalr for address inside code cache
   __ far_call(StubRoutines::method_entry_barrier());
 
+  // emits auipc + jr assuming continuation is not near
   __ j(continuation());
 
   // make guard value 4-byte aligned so that it can be accessed atomically