hotspot/src/share/vm/interpreter/rewriter.cpp - platform/libcore - Git at Google

 /*
  * Copyright 1998-2009 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.
  *
  */

 # include "incls/_precompiled.incl"
 # include "incls/_rewriter.cpp.incl"

 // Computes a CPC map (new_index -> original_index) for constant pool entries
 // that are referred to by the interpreter at runtime via the constant pool cache.
 // Also computes a CP map (original_index -> new_index).
 // Marks entries in CP which require additional processing.
 void Rewriter::compute_index_maps() {
   const int length  = _pool->length();
   init_cp_map(length);
   for (int i = 0; i < length; i++) {
     int tag = _pool->tag_at(i).value();
     switch (tag) {
       case JVM_CONSTANT_InterfaceMethodref:
       case JVM_CONSTANT_Fieldref          : // fall through
       case JVM_CONSTANT_Methodref         : // fall through
         add_cp_cache_entry(i);
         break;
     }
   }

   guarantee((int)_cp_cache_map.length()-1 <= (int)((u2)-1),
             "all cp cache indexes fit in a u2");
 }


 int Rewriter::add_extra_cp_cache_entry(int main_entry) {
   // Hack: We put it on the map as an encoded value.
   // The only place that consumes this is ConstantPoolCacheEntry::set_initial_state
   int encoded = constantPoolCacheOopDesc::encode_secondary_index(main_entry);
   int plain_secondary_index = _cp_cache_map.append(encoded);
   return constantPoolCacheOopDesc::encode_secondary_index(plain_secondary_index);
 }


 // Creates a constant pool cache given a CPC map
 // This creates the constant pool cache initially in a state
 // that is unsafe for concurrent GC processing but sets it to
 // a safe mode before the constant pool cache is returned.
 void Rewriter::make_constant_pool_cache(TRAPS) {
   const int length = _cp_cache_map.length();
   constantPoolCacheOop cache =
       oopFactory::new_constantPoolCache(length, methodOopDesc::IsUnsafeConc, CHECK);
   cache->initialize(_cp_cache_map);
   _pool->set_cache(cache);
   cache->set_constant_pool(_pool());
 }


 // The new finalization semantics says that registration of
 // finalizable objects must be performed on successful return from the
 // Object.<init> constructor.  We could implement this trivially if
 // <init> were never rewritten but since JVMTI allows this to occur, a
 // more complicated solution is required.  A special return bytecode
 // is used only by Object.<init> to signal the finalization
 // registration point.  Additionally local 0 must be preserved so it's
 // available to pass to the registration function.  For simplicty we
 // require that local 0 is never overwritten so it's available as an
 // argument for registration.

 void Rewriter::rewrite_Object_init(methodHandle method, TRAPS) {
   RawBytecodeStream bcs(method);
   while (!bcs.is_last_bytecode()) {
     Bytecodes::Code opcode = bcs.raw_next();
     switch (opcode) {
       case Bytecodes::_return: *bcs.bcp() = Bytecodes::_return_register_finalizer; break;

       case Bytecodes::_istore:
       case Bytecodes::_lstore:
       case Bytecodes::_fstore:
       case Bytecodes::_dstore:
       case Bytecodes::_astore:
         if (bcs.get_index() != 0) continue;

         // fall through
       case Bytecodes::_istore_0:
       case Bytecodes::_lstore_0:
       case Bytecodes::_fstore_0:
       case Bytecodes::_dstore_0:
       case Bytecodes::_astore_0:
         THROW_MSG(vmSymbols::java_lang_IncompatibleClassChangeError(),
                   "can't overwrite local 0 in Object.<init>");
         break;
     }
   }
 }


 // Rewrite a classfile-order CP index into a native-order CPC index.
 int Rewriter::rewrite_member_reference(address bcp, int offset) {
   address p = bcp + offset;
   int  cp_index    = Bytes::get_Java_u2(p);
   int  cache_index = cp_entry_to_cp_cache(cp_index);
   Bytes::put_native_u2(p, cache_index);
   return cp_index;
 }


 void Rewriter::rewrite_invokedynamic(address bcp, int offset, int delete_me) {
   address p = bcp + offset;
   assert(p[-1] == Bytecodes::_invokedynamic, "");
   int cp_index = Bytes::get_Java_u2(p);
   int cpc  = maybe_add_cp_cache_entry(cp_index);  // add lazily
   int cpc2 = add_extra_cp_cache_entry(cpc);

   // Replace the trailing four bytes with a CPC index for the dynamic
   // call site.  Unlike other CPC entries, there is one per bytecode,
   // not just one per distinct CP entry.  In other words, the
   // CPC-to-CP relation is many-to-one for invokedynamic entries.
   // This means we must use a larger index size than u2 to address
   // all these entries.  That is the main reason invokedynamic
   // must have a five-byte instruction format.  (Of course, other JVM
   // implementations can use the bytes for other purposes.)
   Bytes::put_native_u4(p, cpc2);
   // Note: We use native_u4 format exclusively for 4-byte indexes.
 }


 // Rewrites a method given the index_map information
 void Rewriter::scan_method(methodOop method) {

   int nof_jsrs = 0;
   bool has_monitor_bytecodes = false;

   {
     // We cannot tolerate a GC in this block, because we've
     // cached the bytecodes in 'code_base'. If the methodOop
     // moves, the bytecodes will also move.
     No_Safepoint_Verifier nsv;
     Bytecodes::Code c;

     // Bytecodes and their length
     const address code_base = method->code_base();
     const int code_length = method->code_size();

     int bc_length;
     for (int bci = 0; bci < code_length; bci += bc_length) {
       address bcp = code_base + bci;
       int prefix_length = 0;
       c = (Bytecodes::Code)(*bcp);

       // Since we have the code, see if we can get the length
       // directly. Some more complicated bytecodes will report
       // a length of zero, meaning we need to make another method
       // call to calculate the length.
       bc_length = Bytecodes::length_for(c);
       if (bc_length == 0) {
         bc_length = Bytecodes::length_at(bcp);

         // length_at will put us at the bytecode after the one modified
         // by 'wide'. We don't currently examine any of the bytecodes
         // modified by wide, but in case we do in the future...
         if (c == Bytecodes::_wide) {
           prefix_length = 1;
           c = (Bytecodes::Code)bcp[1];
         }
       }

       assert(bc_length != 0, "impossible bytecode length");

       switch (c) {
         case Bytecodes::_lookupswitch   : {
 #ifndef CC_INTERP
           Bytecode_lookupswitch* bc = Bytecode_lookupswitch_at(bcp);
           bc->set_code(
             bc->number_of_pairs() < BinarySwitchThreshold
             ? Bytecodes::_fast_linearswitch
             : Bytecodes::_fast_binaryswitch
           );
 #endif
           break;
         }
         case Bytecodes::_getstatic      : // fall through
         case Bytecodes::_putstatic      : // fall through
         case Bytecodes::_getfield       : // fall through
         case Bytecodes::_putfield       : // fall through
         case Bytecodes::_invokevirtual  : // fall through
         case Bytecodes::_invokespecial  : // fall through
         case Bytecodes::_invokestatic   :
         case Bytecodes::_invokeinterface:
           rewrite_member_reference(bcp, prefix_length+1);
           break;
         case Bytecodes::_invokedynamic:
           rewrite_invokedynamic(bcp, prefix_length+1, int(sizeof"@@@@DELETE ME"));
           break;
         case Bytecodes::_jsr            : // fall through
         case Bytecodes::_jsr_w          : nof_jsrs++;                   break;
         case Bytecodes::_monitorenter   : // fall through
         case Bytecodes::_monitorexit    : has_monitor_bytecodes = true; break;
       }
     }
   }

   // Update access flags
   if (has_monitor_bytecodes) {
     method->set_has_monitor_bytecodes();
   }

   // The present of a jsr bytecode implies that the method might potentially
   // have to be rewritten, so we run the oopMapGenerator on the method
   if (nof_jsrs > 0) {
     method->set_has_jsrs();
     // Second pass will revisit this method.
     assert(method->has_jsrs(), "");
   }
 }

 // After constant pool is created, revisit methods containing jsrs.
 methodHandle Rewriter::rewrite_jsrs(methodHandle method, TRAPS) {
   ResolveOopMapConflicts romc(method);
   methodHandle original_method = method;
   method = romc.do_potential_rewrite(CHECK_(methodHandle()));
   if (method() != original_method()) {
     // Insert invalid bytecode into original methodOop and set
     // interpreter entrypoint, so that a executing this method
     // will manifest itself in an easy recognizable form.
     address bcp = original_method->bcp_from(0);
     *bcp = (u1)Bytecodes::_shouldnotreachhere;
     int kind = Interpreter::method_kind(original_method);
     original_method->set_interpreter_kind(kind);
   }

   // Update monitor matching info.
   if (romc.monitor_safe()) {
     method->set_guaranteed_monitor_matching();
   }

   return method;
 }


 void Rewriter::rewrite(instanceKlassHandle klass, TRAPS) {
   ResourceMark rm(THREAD);
   Rewriter     rw(klass, CHECK);
   // (That's all, folks.)
 }

 Rewriter::Rewriter(instanceKlassHandle klass, TRAPS)
   : _klass(klass),
     // gather starting points
     _pool(   THREAD, klass->constants()),
     _methods(THREAD, klass->methods())
 {
   assert(_pool->cache() == NULL, "constant pool cache must not be set yet");

   // determine index maps for methodOop rewriting
   compute_index_maps();

   if (RegisterFinalizersAtInit && _klass->name() == vmSymbols::java_lang_Object()) {
     int i = _methods->length();
     while (i-- > 0) {
       methodOop method = (methodOop)_methods->obj_at(i);
       if (method->intrinsic_id() == vmIntrinsics::_Object_init) {
         // rewrite the return bytecodes of Object.<init> to register the
         // object for finalization if needed.
         methodHandle m(THREAD, method);
         rewrite_Object_init(m, CHECK);
         break;
       }
     }
   }

   // rewrite methods, in two passes
   int i, len = _methods->length();

   for (i = len; --i >= 0; ) {
     methodOop method = (methodOop)_methods->obj_at(i);
     scan_method(method);
   }

   // allocate constant pool cache, now that we've seen all the bytecodes
   make_constant_pool_cache(CHECK);

   for (i = len; --i >= 0; ) {
     methodHandle m(THREAD, (methodOop)_methods->obj_at(i));

     if (m->has_jsrs()) {
       m = rewrite_jsrs(m, CHECK);
       // Method might have gotten rewritten.
       _methods->obj_at_put(i, m());
     }

     // Set up method entry points for compiler and interpreter.
     m->link_method(m, CHECK);
   }
 }
	/*
	* Copyright 1998-2009 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.
	*
	*/

	# include "incls/_precompiled.incl"
	# include "incls/_rewriter.cpp.incl"

	// Computes a CPC map (new_index -> original_index) for constant pool entries
	// that are referred to by the interpreter at runtime via the constant pool cache.
	// Also computes a CP map (original_index -> new_index).
	// Marks entries in CP which require additional processing.
	void Rewriter::compute_index_maps() {
	const int length = _pool->length();
	init_cp_map(length);
	for (int i = 0; i < length; i++) {
	int tag = _pool->tag_at(i).value();
	switch (tag) {
	case JVM_CONSTANT_InterfaceMethodref:
	case JVM_CONSTANT_Fieldref : // fall through
	case JVM_CONSTANT_Methodref : // fall through
	add_cp_cache_entry(i);
	break;
	}
	}

	guarantee((int)_cp_cache_map.length()-1 <= (int)((u2)-1),
	"all cp cache indexes fit in a u2");
	}


	int Rewriter::add_extra_cp_cache_entry(int main_entry) {
	// Hack: We put it on the map as an encoded value.
	// The only place that consumes this is ConstantPoolCacheEntry::set_initial_state
	int encoded = constantPoolCacheOopDesc::encode_secondary_index(main_entry);
	int plain_secondary_index = _cp_cache_map.append(encoded);
	return constantPoolCacheOopDesc::encode_secondary_index(plain_secondary_index);
	}



	// Creates a constant pool cache given a CPC map
	// This creates the constant pool cache initially in a state
	// that is unsafe for concurrent GC processing but sets it to
	// a safe mode before the constant pool cache is returned.
	void Rewriter::make_constant_pool_cache(TRAPS) {
	const int length = _cp_cache_map.length();
	constantPoolCacheOop cache =
	oopFactory::new_constantPoolCache(length, methodOopDesc::IsUnsafeConc, CHECK);
	cache->initialize(_cp_cache_map);
	_pool->set_cache(cache);
	cache->set_constant_pool(_pool());
	}



	// The new finalization semantics says that registration of
	// finalizable objects must be performed on successful return from the
	// Object.<init> constructor. We could implement this trivially if
	// <init> were never rewritten but since JVMTI allows this to occur, a
	// more complicated solution is required. A special return bytecode
	// is used only by Object.<init> to signal the finalization
	// registration point. Additionally local 0 must be preserved so it's
	// available to pass to the registration function. For simplicty we
	// require that local 0 is never overwritten so it's available as an
	// argument for registration.

	void Rewriter::rewrite_Object_init(methodHandle method, TRAPS) {
	RawBytecodeStream bcs(method);
	while (!bcs.is_last_bytecode()) {
	Bytecodes::Code opcode = bcs.raw_next();
	switch (opcode) {
	case Bytecodes::_return: *bcs.bcp() = Bytecodes::_return_register_finalizer; break;

	case Bytecodes::_istore:
	case Bytecodes::_lstore:
	case Bytecodes::_fstore:
	case Bytecodes::_dstore:
	case Bytecodes::_astore:
	if (bcs.get_index() != 0) continue;

	// fall through
	case Bytecodes::_istore_0:
	case Bytecodes::_lstore_0:
	case Bytecodes::_fstore_0:
	case Bytecodes::_dstore_0:
	case Bytecodes::_astore_0:
	THROW_MSG(vmSymbols::java_lang_IncompatibleClassChangeError(),
	"can't overwrite local 0 in Object.<init>");
	break;
	}
	}
	}


	// Rewrite a classfile-order CP index into a native-order CPC index.
	int Rewriter::rewrite_member_reference(address bcp, int offset) {
	address p = bcp + offset;
	int cp_index = Bytes::get_Java_u2(p);
	int cache_index = cp_entry_to_cp_cache(cp_index);
	Bytes::put_native_u2(p, cache_index);
	return cp_index;
	}


	void Rewriter::rewrite_invokedynamic(address bcp, int offset, int delete_me) {
	address p = bcp + offset;
	assert(p[-1] == Bytecodes::_invokedynamic, "");
	int cp_index = Bytes::get_Java_u2(p);
	int cpc = maybe_add_cp_cache_entry(cp_index); // add lazily
	int cpc2 = add_extra_cp_cache_entry(cpc);

	// Replace the trailing four bytes with a CPC index for the dynamic
	// call site. Unlike other CPC entries, there is one per bytecode,
	// not just one per distinct CP entry. In other words, the
	// CPC-to-CP relation is many-to-one for invokedynamic entries.
	// This means we must use a larger index size than u2 to address
	// all these entries. That is the main reason invokedynamic
	// must have a five-byte instruction format. (Of course, other JVM
	// implementations can use the bytes for other purposes.)
	Bytes::put_native_u4(p, cpc2);
	// Note: We use native_u4 format exclusively for 4-byte indexes.
	}


	// Rewrites a method given the index_map information
	void Rewriter::scan_method(methodOop method) {

	int nof_jsrs = 0;
	bool has_monitor_bytecodes = false;

	{
	// We cannot tolerate a GC in this block, because we've
	// cached the bytecodes in 'code_base'. If the methodOop
	// moves, the bytecodes will also move.
	No_Safepoint_Verifier nsv;
	Bytecodes::Code c;

	// Bytecodes and their length
	const address code_base = method->code_base();
	const int code_length = method->code_size();

	int bc_length;
	for (int bci = 0; bci < code_length; bci += bc_length) {
	address bcp = code_base + bci;
	int prefix_length = 0;
	c = (Bytecodes::Code)(*bcp);

	// Since we have the code, see if we can get the length
	// directly. Some more complicated bytecodes will report
	// a length of zero, meaning we need to make another method
	// call to calculate the length.
	bc_length = Bytecodes::length_for(c);
	if (bc_length == 0) {
	bc_length = Bytecodes::length_at(bcp);

	// length_at will put us at the bytecode after the one modified
	// by 'wide'. We don't currently examine any of the bytecodes
	// modified by wide, but in case we do in the future...
	if (c == Bytecodes::_wide) {
	prefix_length = 1;
	c = (Bytecodes::Code)bcp[1];
	}
	}

	assert(bc_length != 0, "impossible bytecode length");

	switch (c) {
	case Bytecodes::_lookupswitch : {
	#ifndef CC_INTERP
	Bytecode_lookupswitch* bc = Bytecode_lookupswitch_at(bcp);
	bc->set_code(
	bc->number_of_pairs() < BinarySwitchThreshold
	? Bytecodes::_fast_linearswitch
	: Bytecodes::_fast_binaryswitch
	);
	#endif
	break;
	}
	case Bytecodes::_getstatic : // fall through
	case Bytecodes::_putstatic : // fall through
	case Bytecodes::_getfield : // fall through
	case Bytecodes::_putfield : // fall through
	case Bytecodes::_invokevirtual : // fall through
	case Bytecodes::_invokespecial : // fall through
	case Bytecodes::_invokestatic :
	case Bytecodes::_invokeinterface:
	rewrite_member_reference(bcp, prefix_length+1);
	break;
	case Bytecodes::_invokedynamic:
	rewrite_invokedynamic(bcp, prefix_length+1, int(sizeof"@@@@DELETE ME"));
	break;
	case Bytecodes::_jsr : // fall through
	case Bytecodes::_jsr_w : nof_jsrs++; break;
	case Bytecodes::_monitorenter : // fall through
	case Bytecodes::_monitorexit : has_monitor_bytecodes = true; break;
	}
	}
	}

	// Update access flags
	if (has_monitor_bytecodes) {
	method->set_has_monitor_bytecodes();
	}

	// The present of a jsr bytecode implies that the method might potentially
	// have to be rewritten, so we run the oopMapGenerator on the method
	if (nof_jsrs > 0) {
	method->set_has_jsrs();
	// Second pass will revisit this method.
	assert(method->has_jsrs(), "");
	}
	}

	// After constant pool is created, revisit methods containing jsrs.
	methodHandle Rewriter::rewrite_jsrs(methodHandle method, TRAPS) {
	ResolveOopMapConflicts romc(method);
	methodHandle original_method = method;
	method = romc.do_potential_rewrite(CHECK_(methodHandle()));
	if (method() != original_method()) {
	// Insert invalid bytecode into original methodOop and set
	// interpreter entrypoint, so that a executing this method
	// will manifest itself in an easy recognizable form.
	address bcp = original_method->bcp_from(0);
	*bcp = (u1)Bytecodes::_shouldnotreachhere;
	int kind = Interpreter::method_kind(original_method);
	original_method->set_interpreter_kind(kind);
	}

	// Update monitor matching info.
	if (romc.monitor_safe()) {
	method->set_guaranteed_monitor_matching();
	}

	return method;
	}


	void Rewriter::rewrite(instanceKlassHandle klass, TRAPS) {
	ResourceMark rm(THREAD);
	Rewriter rw(klass, CHECK);
	// (That's all, folks.)
	}

	Rewriter::Rewriter(instanceKlassHandle klass, TRAPS)
	: _klass(klass),
	// gather starting points
	_pool( THREAD, klass->constants()),
	_methods(THREAD, klass->methods())
	{
	assert(_pool->cache() == NULL, "constant pool cache must not be set yet");

	// determine index maps for methodOop rewriting
	compute_index_maps();

	if (RegisterFinalizersAtInit && _klass->name() == vmSymbols::java_lang_Object()) {
	int i = _methods->length();
	while (i-- > 0) {
	methodOop method = (methodOop)_methods->obj_at(i);
	if (method->intrinsic_id() == vmIntrinsics::_Object_init) {
	// rewrite the return bytecodes of Object.<init> to register the
	// object for finalization if needed.
	methodHandle m(THREAD, method);
	rewrite_Object_init(m, CHECK);
	break;
	}
	}
	}

	// rewrite methods, in two passes
	int i, len = _methods->length();

	for (i = len; --i >= 0; ) {
	methodOop method = (methodOop)_methods->obj_at(i);
	scan_method(method);
	}

	// allocate constant pool cache, now that we've seen all the bytecodes
	make_constant_pool_cache(CHECK);

	for (i = len; --i >= 0; ) {
	methodHandle m(THREAD, (methodOop)_methods->obj_at(i));

	if (m->has_jsrs()) {
	m = rewrite_jsrs(m, CHECK);
	// Method might have gotten rewritten.
	_methods->obj_at_put(i, m());
	}

	// Set up method entry points for compiler and interpreter.
	m->link_method(m, CHECK);
	}
	}