8081406: cleanup and minor extensions of the debugging facilities in CodeStrings

Avoid issues around _defunct CodeStrings

Reviewed-by: dholmes, coleenp

hotspot/src/share/vm/asm/codeBuffer.cpp

@@ -1093,9 +1093,11 @@ void CodeStrings::add_comment(intptr_t offset, const char * comment) {
 
 void CodeStrings::assign(CodeStrings& other) {
   other.check_valid();
-  // Cannot do following because CodeStrings constructor is not alway run!
   assert(is_null(), "Cannot assign onto non-empty CodeStrings");
   _strings = other._strings;
+#ifdef ASSERT
+  _defunct = false;
+#endif
   other.set_null_and_invalidate();
 }
 
@@ -1115,13 +1117,15 @@ void CodeStrings::copy(CodeStrings& other) {
   }
 }
 
+const char* CodeStrings::_prefix = " ;; ";  // default: can be changed via set_prefix
+
 void CodeStrings::print_block_comment(outputStream* stream, intptr_t offset) const {
     check_valid();
     if (_strings != NULL) {
     CodeString* c = find(offset);
     while (c && c->offset() == offset) {
       stream->bol();
-      stream->print("  ;; ");
+      stream->print("%s", _prefix);
       stream->print_cr("%s", c->string());
       c = c->next_comment();
     }

hotspot/src/share/vm/asm/codeBuffer.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2015, 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
@@ -249,6 +249,7 @@ private:
   // Becomes true after copy-out, forbids further use.
   bool _defunct; // Zero bit pattern is "valid", see memset call in decode_env::decode_env
 #endif
+  static const char* _prefix; // defaults to " ;; "
 #endif
 
   CodeString* find(intptr_t offset) const;
@@ -289,11 +290,18 @@ public:
   void assign(CodeStrings& other)  PRODUCT_RETURN;
   // COPY strings from other to this; leave other valid.
   void copy(CodeStrings& other)  PRODUCT_RETURN;
+  // FREE strings; invalidate this.
   void free() PRODUCT_RETURN;
-  // Guarantee that _strings are used at most once; assign invalidates a buffer.
+  // Guarantee that _strings are used at most once; assign and free invalidate a buffer.
   inline void check_valid() const {
 #ifdef ASSERT
     assert(!_defunct, "Use of invalid CodeStrings");
+#endif
+  }
+
+  static void set_prefix(const char *prefix) {
+#ifndef PRODUCT
+    _prefix = prefix;
 #endif
   }
 };
@@ -379,6 +387,7 @@ class CodeBuffer: public StackObj {
     _oop_recorder    = NULL;
     _decode_begin    = NULL;
     _overflow_arena  = NULL;
+    _code_strings    = CodeStrings();
   }
 
   void initialize(address code_start, csize_t code_size) {

hotspot/src/share/vm/code/codeBlob.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2015, 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
@@ -88,6 +88,7 @@ CodeBlob::CodeBlob(const char* name, int header_size, int size, int frame_comple
   _data_offset           = size;
   _frame_size            =  0;
   set_oop_maps(NULL);
+  _strings               = CodeStrings();
 }
 
 
@@ -114,6 +115,7 @@ CodeBlob::CodeBlob(
   _code_offset           = _content_offset + cb->total_offset_of(cb->insts());
   _data_offset           = _content_offset + round_to(cb->total_content_size(), oopSize);
   assert(_data_offset <= size, "codeBlob is too small");
+  _strings               = CodeStrings();
 
   cb->copy_code_and_locs_to(this);
   set_oop_maps(oop_maps);