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 an index_map (new_index -> original_index) for contant pool entries
 // that are referred to by the interpreter at runtime via the constant pool cache.
 void Rewriter::compute_index_maps(constantPoolHandle pool, intArray*& index_map, intStack*& inverse_index_map) {
   const int length  = pool->length();
   index_map         = new intArray(length, -1);
   // Choose an initial value large enough that we don't get frequent
   // calls to grow().
   inverse_index_map = new intStack(length / 2);
   for (int i = 0; i < length; i++) {
     switch (pool->tag_at(i).value()) {
       case JVM_CONSTANT_Fieldref          : // fall through
       case JVM_CONSTANT_Methodref         : // fall through
       case JVM_CONSTANT_InterfaceMethodref: {
         index_map->at_put(i, inverse_index_map->length());
         inverse_index_map->append(i);
       }
     }
   }
 }


 // Creates a constant pool cache given an inverse_index_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.
 constantPoolCacheHandle Rewriter::new_constant_pool_cache(intArray& inverse_index_map, TRAPS) {
   const int length = inverse_index_map.length();
   constantPoolCacheOop cache = oopFactory::new_constantPoolCache(length,
                                              methodOopDesc::IsUnsafeConc,
                                              CHECK_(constantPoolCacheHandle()));
   cache->initialize(inverse_index_map);
   return constantPoolCacheHandle(THREAD, cache);
 }


 // 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;
     }
   }
 }


 // Rewrites a method given the index_map information
 methodHandle Rewriter::rewrite_method(methodHandle method, intArray& index_map, TRAPS) {

   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;
       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) {
           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   : // fall through
         case Bytecodes::_invokeinterface: {
           address p = bcp + 1;
           Bytes::put_native_u2(p, index_map[Bytes::get_Java_u2(p)]);
           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();
     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();
     }
   }

   // Setup method entrypoints for compiler and interpreter
   method->link_method(method, CHECK_(methodHandle()));

   return method;
 }


 void Rewriter::rewrite(instanceKlassHandle klass, TRAPS) {
   // gather starting points
   ResourceMark rm(THREAD);
   constantPoolHandle pool (THREAD, klass->constants());
   objArrayHandle methods  (THREAD, klass->methods());
   assert(pool->cache() == NULL, "constant pool cache must not be set yet");

   // determine index maps for methodOop rewriting
   intArray* index_map         = NULL;
   intStack* inverse_index_map = NULL;
   compute_index_maps(pool, index_map, inverse_index_map);

   // allocate constant pool cache
   constantPoolCacheHandle cache = new_constant_pool_cache(*inverse_index_map, CHECK);
   pool->set_cache(cache());
   cache->set_constant_pool(pool());

   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
   { int i = methods->length();
     while (i-- > 0) {
       methodHandle m(THREAD, (methodOop)methods->obj_at(i));
       m = rewrite_method(m, *index_map, CHECK);
       // Method might have gotten rewritten.
       methods->obj_at_put(i, m());
     }
   }
 }
	/*
	* 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 an index_map (new_index -> original_index) for contant pool entries
	// that are referred to by the interpreter at runtime via the constant pool cache.
	void Rewriter::compute_index_maps(constantPoolHandle pool, intArray& index_map, intStack& inverse_index_map) {
	const int length = pool->length();
	index_map = new intArray(length, -1);
	// Choose an initial value large enough that we don't get frequent
	// calls to grow().
	inverse_index_map = new intStack(length / 2);
	for (int i = 0; i < length; i++) {
	switch (pool->tag_at(i).value()) {
	case JVM_CONSTANT_Fieldref : // fall through
	case JVM_CONSTANT_Methodref : // fall through
	case JVM_CONSTANT_InterfaceMethodref: {
	index_map->at_put(i, inverse_index_map->length());
	inverse_index_map->append(i);
	}
	}
	}
	}


	// Creates a constant pool cache given an inverse_index_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.
	constantPoolCacheHandle Rewriter::new_constant_pool_cache(intArray& inverse_index_map, TRAPS) {
	const int length = inverse_index_map.length();
	constantPoolCacheOop cache = oopFactory::new_constantPoolCache(length,
	methodOopDesc::IsUnsafeConc,
	CHECK_(constantPoolCacheHandle()));
	cache->initialize(inverse_index_map);
	return constantPoolCacheHandle(THREAD, cache);
	}



	// 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;
	}
	}
	}


	// Rewrites a method given the index_map information
	methodHandle Rewriter::rewrite_method(methodHandle method, intArray& index_map, TRAPS) {

	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;
	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) {
	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 : // fall through
	case Bytecodes::_invokeinterface: {
	address p = bcp + 1;
	Bytes::put_native_u2(p, index_map[Bytes::get_Java_u2(p)]);
	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();
	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();
	}
	}

	// Setup method entrypoints for compiler and interpreter
	method->link_method(method, CHECK_(methodHandle()));

	return method;
	}


	void Rewriter::rewrite(instanceKlassHandle klass, TRAPS) {
	// gather starting points
	ResourceMark rm(THREAD);
	constantPoolHandle pool (THREAD, klass->constants());
	objArrayHandle methods (THREAD, klass->methods());
	assert(pool->cache() == NULL, "constant pool cache must not be set yet");

	// determine index maps for methodOop rewriting
	intArray* index_map = NULL;
	intStack* inverse_index_map = NULL;
	compute_index_maps(pool, index_map, inverse_index_map);

	// allocate constant pool cache
	constantPoolCacheHandle cache = new_constant_pool_cache(*inverse_index_map, CHECK);
	pool->set_cache(cache());
	cache->set_constant_pool(pool());

	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
	{ int i = methods->length();
	while (i-- > 0) {
	methodHandle m(THREAD, (methodOop)methods->obj_at(i));
	m = rewrite_method(m, *index_map, CHECK);
	// Method might have gotten rewritten.
	methods->obj_at_put(i, m());
	}
	}
	}