/* * Copyright (c) 1998, 2010, 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 * 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "precompiled.hpp" #include "interpreter/bytecodes.hpp" #include "interpreter/interpreter.hpp" #include "interpreter/rewriter.hpp" #include "memory/gcLocker.hpp" #include "memory/oopFactory.hpp" #include "memory/resourceArea.hpp" #include "oops/generateOopMap.hpp" #include "oops/objArrayOop.hpp" #include "oops/oop.inline.hpp" #include "prims/methodComparator.hpp" // 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); jint tag_mask = 0; for (int i = 0; i < length; i++) { int tag = _pool->tag_at(i).value(); tag_mask |= (1 << tag); switch (tag) { case JVM_CONSTANT_InterfaceMethodref: case JVM_CONSTANT_Fieldref : // fall through case JVM_CONSTANT_Methodref : // fall through case JVM_CONSTANT_MethodHandle : // fall through case JVM_CONSTANT_MethodType : // fall through case JVM_CONSTANT_InvokeDynamic : // 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"); _have_invoke_dynamic = ((tag_mask & (1 << JVM_CONSTANT_InvokeDynamic)) != 0); } // 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); // Don't bother to the next pass if there is no JVM_CONSTANT_InvokeDynamic. if (_have_invoke_dynamic) { for (int i = 0; i < length; i++) { int pool_index = cp_cache_entry_pool_index(i); if (pool_index >= 0 && _pool->tag_at(pool_index).is_invoke_dynamic()) { int bsm_index = _pool->invoke_dynamic_bootstrap_method_ref_index_at(pool_index); if (bsm_index != 0) { assert(_pool->tag_at(bsm_index).is_method_handle(), "must be a MH constant"); // There is a CP cache entry holding the BSM for these calls. int bsm_cache_index = cp_entry_to_cp_cache(bsm_index); cache->entry_at(i)->initialize_bootstrap_method_index_in_cache(bsm_cache_index); } else { // There is no CP cache entry holding the BSM for these calls. // We will need to look for a class-global BSM, later. guarantee(AllowTransitionalJSR292, ""); } } } } _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. constructor. We could implement this trivially if // 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. 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."); break; } } } // Rewrite a classfile-order CP index into a native-order CPC index. void 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); } void Rewriter::rewrite_invokedynamic(address bcp, int offset) { 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_secondary_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, constantPoolCacheOopDesc::encode_secondary_index(cpc2)); // Note: We use native_u4 format exclusively for 4-byte indexes. } // Rewrite some ldc bytecodes to _fast_aldc void Rewriter::maybe_rewrite_ldc(address bcp, int offset, bool is_wide) { assert((*bcp) == (is_wide ? Bytecodes::_ldc_w : Bytecodes::_ldc), ""); address p = bcp + offset; int cp_index = is_wide ? Bytes::get_Java_u2(p) : (u1)(*p); constantTag tag = _pool->tag_at(cp_index).value(); if (tag.is_method_handle() || tag.is_method_type()) { int cache_index = cp_entry_to_cp_cache(cp_index); if (is_wide) { (*bcp) = Bytecodes::_fast_aldc_w; assert(cache_index == (u2)cache_index, ""); Bytes::put_native_u2(p, cache_index); } else { (*bcp) = Bytecodes::_fast_aldc; assert(cache_index == (u1)cache_index, ""); (*p) = (u1)cache_index; } } } // 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); (*bcp) = ( 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); break; case Bytecodes::_ldc: maybe_rewrite_ldc(bcp, prefix_length+1, false); break; case Bytecodes::_ldc_w: maybe_rewrite_ldc(bcp, prefix_length+1, true); 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, klass->constants(), klass->methods(), CHECK); // (That's all, folks.) } void Rewriter::rewrite(instanceKlassHandle klass, constantPoolHandle cpool, objArrayHandle methods, TRAPS) { ResourceMark rm(THREAD); Rewriter rw(klass, cpool, methods, CHECK); // (That's all, folks.) } Rewriter::Rewriter(instanceKlassHandle klass, constantPoolHandle cpool, objArrayHandle methods, TRAPS) : _klass(klass), _pool(cpool), _methods(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()) { bool did_rewrite = false; 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. to register the // object for finalization if needed. methodHandle m(THREAD, method); rewrite_Object_init(m, CHECK); did_rewrite = true; break; } } assert(did_rewrite, "must find Object:: to rewrite it"); } // 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); #ifdef ASSERT if (StressMethodComparator) { static int nmc = 0; for (int j = i; j >= 0 && j >= i-4; j--) { if ((++nmc % 1000) == 0) tty->print_cr("Have run MethodComparator %d times...", nmc); bool z = MethodComparator::methods_EMCP(m(), (methodOop)_methods->obj_at(j)); if (j == i && !z) { tty->print("MethodComparator FAIL: "); m->print(); m->print_codes(); assert(z, "method must compare equal to itself"); } } } #endif //ASSERT } }