8268641: [foreign] assert(allocates2(pc)) failed: not in CodeBuffer memory with ShenandoahGC

Reviewed-by: rbackman, kvn

Author: DamonFool

src/hotspot/cpu/x86/universalUpcallHandler_x86_64.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2021, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -585,7 +585,7 @@ address ProgrammableUpcallHandler::generate_optimized_upcall_stub(jobject receiv
   const ABIDescriptor abi = ForeignGlobals::parse_abi_descriptor(jabi);
   const CallRegs conv = ForeignGlobals::parse_call_regs(jconv);
   assert(conv._rets_length <= 1, "no multi reg returns");
-  CodeBuffer buffer("upcall_stub_linkToNative", /* code_size = */ 1024, /* locs_size = */ 1024);
+  CodeBuffer buffer("upcall_stub_linkToNative", /* code_size = */ 2048, /* locs_size = */ 1024);
 
   int register_size = sizeof(uintptr_t);
   int buffer_alignment = xmm_reg_size;