hotspot/src/share/vm/interpreter/bytecodeStream.hpp
changeset 1 489c9b5090e2
child 2570 ecc7862946d4
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/interpreter/bytecodeStream.hpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,172 @@
+/*
+ * Copyright 1997-2005 Sun Microsystems, Inc.  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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+// A BytecodeStream is used for fast iteration over the bytecodes
+// of a methodOop.
+//
+// Usage:
+//
+// BytecodeStream s(method);
+// Bytecodes::Code c;
+// while ((c = s.next()) >= 0) {
+//   ...
+// }
+//
+// A RawBytecodeStream is a simple version of BytecodeStream.
+// It is used ONLY when we know the bytecodes haven't been rewritten
+// yet, such as in the rewriter or the verifier. Currently only the
+// verifier uses this class.
+
+class RawBytecodeStream: StackObj {
+ protected:
+  // stream buffer
+  methodHandle    _method;                       // read from method directly
+
+  // reading position
+  int             _bci;                          // bci if current bytecode
+  int             _next_bci;                     // bci of next bytecode
+  int             _end_bci;                      // bci after the current iteration interval
+
+  // last bytecode read
+  Bytecodes::Code _code;
+  bool            _is_wide;
+
+ public:
+  // Construction
+  RawBytecodeStream(methodHandle method) : _method(method) {
+    set_interval(0, _method->code_size());
+  }
+
+  // Iteration control
+  void set_interval(int beg_bci, int end_bci) {
+    // iterate over the interval [beg_bci, end_bci)
+    assert(0 <= beg_bci && beg_bci <= method()->code_size(), "illegal beg_bci");
+    assert(0 <= end_bci && end_bci <= method()->code_size(), "illegal end_bci");
+    // setup of iteration pointers
+    _bci      = beg_bci;
+    _next_bci = beg_bci;
+    _end_bci  = end_bci;
+  }
+  void set_start   (int beg_bci) {
+    set_interval(beg_bci, _method->code_size());
+  }
+
+  // Iteration
+  // Use raw_next() rather than next() for faster method reference
+  Bytecodes::Code raw_next() {
+    Bytecodes::Code code;
+    // set reading position
+    _bci = _next_bci;
+    assert(!is_last_bytecode(), "caller should check is_last_bytecode()");
+
+    address bcp = RawBytecodeStream::bcp();
+    code        = Bytecodes::code_or_bp_at(bcp);
+
+    // set next bytecode position
+    int l = Bytecodes::length_for(code);
+    if (l > 0 && (_bci + l) <= _end_bci) {
+      assert(code != Bytecodes::_wide && code != Bytecodes::_tableswitch
+             && code != Bytecodes::_lookupswitch, "can't be special bytecode");
+      _is_wide = false;
+      _next_bci += l;
+      _code = code;
+      return code;
+    } else if (code == Bytecodes::_wide && _bci + 1 >= _end_bci) {
+      return Bytecodes::_illegal;
+    } else {
+      return raw_next_special(code);
+    }
+  }
+  Bytecodes::Code raw_next_special(Bytecodes::Code code);
+
+  // Stream attributes
+  methodHandle    method() const                 { return _method; }
+
+  int             bci() const                    { return _bci; }
+  int             next_bci() const               { return _next_bci; }
+  int             end_bci() const                { return _end_bci; }
+
+  Bytecodes::Code code() const                   { return _code; }
+  bool            is_wide() const                { return _is_wide; }
+  bool            is_last_bytecode() const       { return _next_bci >= _end_bci; }
+
+  address         bcp() const                    { return method()->code_base() + _bci; }
+  address         next_bcp()                     { return method()->code_base() + _next_bci; }
+
+  // State changes
+  void            set_next_bci(int bci)          { assert(0 <= bci && bci <= method()->code_size(), "illegal bci"); _next_bci = bci; }
+
+  // Bytecode-specific attributes
+  int             dest() const                   { return bci() + (short)Bytes::get_Java_u2(bcp() + 1); }
+  int             dest_w() const                 { return bci() + (int  )Bytes::get_Java_u4(bcp() + 1); }
+
+  // Unsigned indices, widening
+  int             get_index() const              { return (is_wide()) ? Bytes::get_Java_u2(bcp() + 2) : bcp()[1]; }
+  int             get_index_big() const          { return (int)Bytes::get_Java_u2(bcp() + 1);  }
+};
+
+// In BytecodeStream, non-java bytecodes will be translated into the
+// corresponding java bytecodes.
+
+class BytecodeStream: public RawBytecodeStream {
+ public:
+  // Construction
+  BytecodeStream(methodHandle method) : RawBytecodeStream(method) { }
+
+  // Iteration
+  Bytecodes::Code next() {
+    Bytecodes::Code code;
+    // set reading position
+    _bci = _next_bci;
+    if (is_last_bytecode()) {
+      // indicate end of bytecode stream
+      code = Bytecodes::_illegal;
+    } else {
+      // get bytecode
+      address bcp = BytecodeStream::bcp();
+      code        = Bytecodes::java_code_at(bcp);
+      // set next bytecode position
+      //
+      // note that we cannot advance before having the
+      // tty bytecode otherwise the stepping is wrong!
+      // (carefull: length_for(...) must be used first!)
+      int l = Bytecodes::length_for(code);
+      if (l == 0) l = Bytecodes::length_at(bcp);
+      _next_bci  += l;
+      assert(_bci < _next_bci, "length must be > 0");
+      // set attributes
+      _is_wide      = false;
+      // check for special (uncommon) cases
+      if (code == Bytecodes::_wide) {
+        code = (Bytecodes::Code)bcp[1];
+        _is_wide = true;
+      }
+      assert(Bytecodes::is_java_code(code), "sanity check");
+    }
+    _code = code;
+    return _code;
+  }
+
+  bool            is_active_breakpoint() const   { return Bytecodes::is_active_breakpoint_at(bcp()); }
+};