/*
* Copyright (c) 1998, 2011, 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"
#include "prims/methodHandles.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);
bool saw_mh_symbol = false;
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
case JVM_CONSTANT_MethodHandle : // fall through
case JVM_CONSTANT_MethodType : // fall through
case JVM_CONSTANT_InvokeDynamic : // fall through
add_cp_cache_entry(i);
break;
case JVM_CONSTANT_Utf8:
if (_pool->symbol_at(i) == vmSymbols::java_lang_invoke_MethodHandle())
saw_mh_symbol = true;
break;
}
}
guarantee((int)_cp_cache_map.length()-1 <= (int)((u2)-1),
"all cp cache indexes fit in a u2");
if (saw_mh_symbol)
_method_handle_invokers.initialize(length, (int)0);
}
// Unrewrite the bytecodes if an error occurs.
void Rewriter::restore_bytecodes() {
int len = _methods->length();
for (int i = len-1; i >= 0; i--) {
methodOop method = (methodOop)_methods->obj_at(i);
scan_method(method, true);
}
}
// Creates a constant pool cache given a CPC map
void Rewriter::make_constant_pool_cache(TRAPS) {
const int length = _cp_cache_map.length();
constantPoolCacheOop cache =
oopFactory::new_constantPoolCache(length, CHECK);
No_Safepoint_Verifier nsv;
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.
void Rewriter::rewrite_member_reference(address bcp, int offset, bool reverse) {
address p = bcp + offset;
if (!reverse) {
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);
if (!_method_handle_invokers.is_empty())
maybe_rewrite_invokehandle(p - 1, cp_index, reverse);
} else {
int cache_index = Bytes::get_native_u2(p);
int pool_index = cp_cache_entry_pool_index(cache_index);
Bytes::put_Java_u2(p, pool_index);
if (!_method_handle_invokers.is_empty())
maybe_rewrite_invokehandle(p - 1, pool_index, reverse);
}
}
// Adjust the invocation bytecode for a signature-polymorphic method (MethodHandle.invoke, etc.)
void Rewriter::maybe_rewrite_invokehandle(address opc, int cp_index, bool reverse) {
if (!reverse) {
if ((*opc) == (u1)Bytecodes::_invokevirtual ||
// allow invokespecial as an alias, although it would be very odd:
(*opc) == (u1)Bytecodes::_invokespecial) {
assert(_pool->tag_at(cp_index).is_method(), "wrong index");
// Determine whether this is a signature-polymorphic method.
if (cp_index >= _method_handle_invokers.length()) return;
int status = _method_handle_invokers[cp_index];
assert(status >= -1 && status <= 1, "oob tri-state");
if (status == 0) {
if (_pool->klass_ref_at_noresolve(cp_index) == vmSymbols::java_lang_invoke_MethodHandle() &&
MethodHandles::is_signature_polymorphic_name(SystemDictionary::MethodHandle_klass(),
_pool->name_ref_at(cp_index))) {
assert(has_cp_cache(cp_index), "should already have an entry");
int cpc = maybe_add_cp_cache_entry(cp_index); // should already have an entry
int cpc2 = add_secondary_cp_cache_entry(cpc);
status = +1;
} else {
status = -1;
}
_method_handle_invokers[cp_index] = status;
}
// We use a special internal bytecode for such methods (if non-static).
// The basic reason for this is that such methods need an extra "appendix" argument
// to transmit the call site's intended call type.
if (status > 0) {
(*opc) = (u1)Bytecodes::_invokehandle;
}
}
} else {
// Do not need to look at cp_index.
if ((*opc) == (u1)Bytecodes::_invokehandle) {
(*opc) = (u1)Bytecodes::_invokevirtual;
// Ignore corner case of original _invokespecial instruction.
// This is safe because (a) the signature polymorphic method was final, and
// (b) the implementation of MethodHandle will not call invokespecial on it.
}
}
}
void Rewriter::rewrite_invokedynamic(address bcp, int offset, bool reverse) {
address p = bcp + offset;
assert(p[-1] == Bytecodes::_invokedynamic, "not invokedynamic bytecode");
if (!reverse) {
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);
// The second secondary entry is required to store the MethodType and
// must be the next entry.
int cpc3 = add_secondary_cp_cache_entry(cpc);
assert(cpc2 + 1 == cpc3, err_msg_res("must be consecutive: %d + 1 == %d", cpc2, cpc3));
// 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.
} else {
int cache_index = constantPoolCacheOopDesc::decode_secondary_index(
Bytes::get_native_u4(p));
int secondary_index = cp_cache_secondary_entry_main_index(cache_index);
int pool_index = cp_cache_entry_pool_index(secondary_index);
assert(_pool->tag_at(pool_index).is_invoke_dynamic(), "wrong index");
// zero out 4 bytes
Bytes::put_Java_u4(p, 0);
Bytes::put_Java_u2(p, pool_index);
}
}
// Rewrite some ldc bytecodes to _fast_aldc
void Rewriter::maybe_rewrite_ldc(address bcp, int offset, bool is_wide,
bool reverse) {
if (!reverse) {
assert((*bcp) == (is_wide ? Bytecodes::_ldc_w : Bytecodes::_ldc), "not ldc bytecode");
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, "index overflow");
Bytes::put_native_u2(p, cache_index);
} else {
(*bcp) = Bytecodes::_fast_aldc;
assert(cache_index == (u1)cache_index, "index overflow");
(*p) = (u1)cache_index;
}
}
} else {
Bytecodes::Code rewritten_bc =
(is_wide ? Bytecodes::_fast_aldc_w : Bytecodes::_fast_aldc);
if ((*bcp) == rewritten_bc) {
address p = bcp + offset;
int cache_index = is_wide ? Bytes::get_native_u2(p) : (u1)(*p);
int pool_index = cp_cache_entry_pool_index(cache_index);
if (is_wide) {
(*bcp) = Bytecodes::_ldc_w;
assert(pool_index == (u2)pool_index, "index overflow");
Bytes::put_Java_u2(p, pool_index);
} else {
(*bcp) = Bytecodes::_ldc;
assert(pool_index == (u1)pool_index, "index overflow");
(*p) = (u1)pool_index;
}
}
}
}
// Rewrites a method given the index_map information
void Rewriter::scan_method(methodOop method, bool reverse) {
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(method, 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(method, bcp);
(*bcp) = (
bc.number_of_pairs() < BinarySwitchThreshold
? Bytecodes::_fast_linearswitch
: Bytecodes::_fast_binaryswitch
);
#endif
break;
}
case Bytecodes::_fast_linearswitch:
case Bytecodes::_fast_binaryswitch: {
#ifndef CC_INTERP
(*bcp) = Bytecodes::_lookupswitch;
#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:
case Bytecodes::_invokehandle : // if reverse=true
rewrite_member_reference(bcp, prefix_length+1, reverse);
break;
case Bytecodes::_invokedynamic:
rewrite_invokedynamic(bcp, prefix_length+1, reverse);
break;
case Bytecodes::_ldc:
case Bytecodes::_fast_aldc: // if reverse=true
maybe_rewrite_ldc(bcp, prefix_length+1, false, reverse);
break;
case Bytecodes::_ldc_w:
case Bytecodes::_fast_aldc_w: // if reverse=true
maybe_rewrite_ldc(bcp, prefix_length+1, true, reverse);
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(), "didn't we just set this?");
}
}
// After constant pool is created, revisit methods containing jsrs.
methodHandle Rewriter::rewrite_jsrs(methodHandle method, TRAPS) {
ResourceMark rm(THREAD);
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.<init> 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::<init> to rewrite it");
}
// rewrite methods, in two passes
int len = _methods->length();
for (int i = len-1; i >= 0; i--) {
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(THREAD);
// Restore bytecodes to their unrewritten state if there are exceptions
// rewriting bytecodes or allocating the cpCache
if (HAS_PENDING_EXCEPTION) {
restore_bytecodes();
return;
}
}
// Relocate jsr/rets in a method. This can't be done with the rewriter
// stage because it can throw other exceptions, leaving the bytecodes
// pointing at constant pool cache entries.
// Link and check jvmti dependencies while we're iterating over the methods.
// JSR292 code calls with a different set of methods, so two entry points.
void Rewriter::relocate_and_link(instanceKlassHandle this_oop, TRAPS) {
objArrayHandle methods(THREAD, this_oop->methods());
relocate_and_link(this_oop, methods, THREAD);
}
void Rewriter::relocate_and_link(instanceKlassHandle this_oop,
objArrayHandle methods, TRAPS) {
int len = methods->length();
for (int i = len-1; i >= 0; i--) {
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);
// This is for JVMTI and unrelated to relocator but the last thing we do
#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
}
}