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/*
* Copyright (c) 1997, 2017, 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/oopMapCache.hpp"
#include "logging/log.hpp"
#include "logging/logStream.hpp"
#include "memory/allocation.inline.hpp"
#include "memory/resourceArea.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/signature.hpp"
class OopMapCacheEntry: private InterpreterOopMap {
friend class InterpreterOopMap;
friend class OopMapForCacheEntry;
friend class OopMapCache;
friend class VerifyClosure;
private:
OopMapCacheEntry* _next;
protected:
// Initialization
void fill(const methodHandle& method, int bci);
// fills the bit mask for native calls
void fill_for_native(const methodHandle& method);
void set_mask(CellTypeState* vars, CellTypeState* stack, int stack_top);
// Deallocate bit masks and initialize fields
void flush();
private:
void allocate_bit_mask(); // allocates the bit mask on C heap f necessary
void deallocate_bit_mask(); // allocates the bit mask on C heap f necessary
bool verify_mask(CellTypeState *vars, CellTypeState *stack, int max_locals, int stack_top);
public:
OopMapCacheEntry() : InterpreterOopMap() {
_next = NULL;
#ifdef ASSERT
_resource_allocate_bit_mask = false;
#endif
}
};
// Implementation of OopMapForCacheEntry
// (subclass of GenerateOopMap, initializes an OopMapCacheEntry for a given method and bci)
class OopMapForCacheEntry: public GenerateOopMap {
OopMapCacheEntry *_entry;
int _bci;
int _stack_top;
virtual bool report_results() const { return false; }
virtual bool possible_gc_point (BytecodeStream *bcs);
virtual void fill_stackmap_prolog (int nof_gc_points);
virtual void fill_stackmap_epilog ();
virtual void fill_stackmap_for_opcodes (BytecodeStream *bcs,
CellTypeState* vars,
CellTypeState* stack,
int stack_top);
virtual void fill_init_vars (GrowableArray<intptr_t> *init_vars);
public:
OopMapForCacheEntry(const methodHandle& method, int bci, OopMapCacheEntry *entry);
// Computes stack map for (method,bci) and initialize entry
void compute_map(TRAPS);
int size();
};
OopMapForCacheEntry::OopMapForCacheEntry(const methodHandle& method, int bci, OopMapCacheEntry* entry) : GenerateOopMap(method) {
_bci = bci;
_entry = entry;
_stack_top = -1;
}
void OopMapForCacheEntry::compute_map(TRAPS) {
assert(!method()->is_native(), "cannot compute oop map for native methods");
// First check if it is a method where the stackmap is always empty
if (method()->code_size() == 0 || method()->max_locals() + method()->max_stack() == 0) {
_entry->set_mask_size(0);
} else {
ResourceMark rm;
GenerateOopMap::compute_map(CATCH);
result_for_basicblock(_bci);
}
}
bool OopMapForCacheEntry::possible_gc_point(BytecodeStream *bcs) {
return false; // We are not reporting any result. We call result_for_basicblock directly
}
void OopMapForCacheEntry::fill_stackmap_prolog(int nof_gc_points) {
// Do nothing
}
void OopMapForCacheEntry::fill_stackmap_epilog() {
// Do nothing
}
void OopMapForCacheEntry::fill_init_vars(GrowableArray<intptr_t> *init_vars) {
// Do nothing
}
void OopMapForCacheEntry::fill_stackmap_for_opcodes(BytecodeStream *bcs,
CellTypeState* vars,
CellTypeState* stack,
int stack_top) {
// Only interested in one specific bci
if (bcs->bci() == _bci) {
_entry->set_mask(vars, stack, stack_top);
_stack_top = stack_top;
}
}
int OopMapForCacheEntry::size() {
assert(_stack_top != -1, "compute_map must be called first");
return ((method()->is_static()) ? 0 : 1) + method()->max_locals() + _stack_top;
}
// Implementation of InterpreterOopMap and OopMapCacheEntry
class VerifyClosure : public OffsetClosure {
private:
OopMapCacheEntry* _entry;
bool _failed;
public:
VerifyClosure(OopMapCacheEntry* entry) { _entry = entry; _failed = false; }
void offset_do(int offset) { if (!_entry->is_oop(offset)) _failed = true; }
bool failed() const { return _failed; }
};
InterpreterOopMap::InterpreterOopMap() {
initialize();
#ifdef ASSERT
_resource_allocate_bit_mask = true;
#endif
}
InterpreterOopMap::~InterpreterOopMap() {
// The expection is that the bit mask was allocated
// last in this resource area. That would make the free of the
// bit_mask effective (see how FREE_RESOURCE_ARRAY does a free).
// If it was not allocated last, there is not a correctness problem
// but the space for the bit_mask is not freed.
assert(_resource_allocate_bit_mask, "Trying to free C heap space");
if (mask_size() > small_mask_limit) {
FREE_RESOURCE_ARRAY(uintptr_t, _bit_mask[0], mask_word_size());
}
}
bool InterpreterOopMap::is_empty() const {
bool result = _method == NULL;
assert(_method != NULL || (_bci == 0 &&
(_mask_size == 0 || _mask_size == USHRT_MAX) &&
_bit_mask[0] == 0), "Should be completely empty");
return result;
}
void InterpreterOopMap::initialize() {
_method = NULL;
_mask_size = USHRT_MAX; // This value should cause a failure quickly
_bci = 0;
_expression_stack_size = 0;
for (int i = 0; i < N; i++) _bit_mask[i] = 0;
}
void InterpreterOopMap::iterate_oop(OffsetClosure* oop_closure) const {
int n = number_of_entries();
int word_index = 0;
uintptr_t value = 0;
uintptr_t mask = 0;
// iterate over entries
for (int i = 0; i < n; i++, mask <<= bits_per_entry) {
// get current word
if (mask == 0) {
value = bit_mask()[word_index++];
mask = 1;
}
// test for oop
if ((value & (mask << oop_bit_number)) != 0) oop_closure->offset_do(i);
}
}
void InterpreterOopMap::print() const {
int n = number_of_entries();
tty->print("oop map for ");
method()->print_value();
tty->print(" @ %d = [%d] { ", bci(), n);
for (int i = 0; i < n; i++) {
if (is_dead(i)) tty->print("%d+ ", i);
else
if (is_oop(i)) tty->print("%d ", i);
}
tty->print_cr("}");
}
class MaskFillerForNative: public NativeSignatureIterator {
private:
uintptr_t * _mask; // the bit mask to be filled
int _size; // the mask size in bits
void set_one(int i) {
i *= InterpreterOopMap::bits_per_entry;
assert(0 <= i && i < _size, "offset out of bounds");
_mask[i / BitsPerWord] |= (((uintptr_t) 1 << InterpreterOopMap::oop_bit_number) << (i % BitsPerWord));
}
public:
void pass_int() { /* ignore */ }
void pass_long() { /* ignore */ }
void pass_float() { /* ignore */ }
void pass_double() { /* ignore */ }
void pass_object() { set_one(offset()); }
MaskFillerForNative(const methodHandle& method, uintptr_t* mask, int size) : NativeSignatureIterator(method) {
_mask = mask;
_size = size;
// initialize with 0
int i = (size + BitsPerWord - 1) / BitsPerWord;
while (i-- > 0) _mask[i] = 0;
}
void generate() {
NativeSignatureIterator::iterate();
}
};
bool OopMapCacheEntry::verify_mask(CellTypeState* vars, CellTypeState* stack, int max_locals, int stack_top) {
// Check mask includes map
VerifyClosure blk(this);
iterate_oop(&blk);
if (blk.failed()) return false;
// Check if map is generated correctly
// (Use ?: operator to make sure all 'true' & 'false' are represented exactly the same so we can use == afterwards)
Log(interpreter, oopmap) logv;
LogStream st(logv.trace());
st.print("Locals (%d): ", max_locals);
for(int i = 0; i < max_locals; i++) {
bool v1 = is_oop(i) ? true : false;
bool v2 = vars[i].is_reference() ? true : false;
assert(v1 == v2, "locals oop mask generation error");
st.print("%d", v1 ? 1 : 0);
}
st.cr();
st.print("Stack (%d): ", stack_top);
for(int j = 0; j < stack_top; j++) {
bool v1 = is_oop(max_locals + j) ? true : false;
bool v2 = stack[j].is_reference() ? true : false;
assert(v1 == v2, "stack oop mask generation error");
st.print("%d", v1 ? 1 : 0);
}
st.cr();
return true;
}
void OopMapCacheEntry::allocate_bit_mask() {
if (mask_size() > small_mask_limit) {
assert(_bit_mask[0] == 0, "bit mask should be new or just flushed");
_bit_mask[0] = (intptr_t)
NEW_C_HEAP_ARRAY(uintptr_t, mask_word_size(), mtClass);
}
}
void OopMapCacheEntry::deallocate_bit_mask() {
if (mask_size() > small_mask_limit && _bit_mask[0] != 0) {
assert(!Thread::current()->resource_area()->contains((void*)_bit_mask[0]),
"This bit mask should not be in the resource area");
FREE_C_HEAP_ARRAY(uintptr_t, _bit_mask[0]);
debug_only(_bit_mask[0] = 0;)
}
}
void OopMapCacheEntry::fill_for_native(const methodHandle& mh) {
assert(mh->is_native(), "method must be native method");
set_mask_size(mh->size_of_parameters() * bits_per_entry);
allocate_bit_mask();
// fill mask for parameters
MaskFillerForNative mf(mh, bit_mask(), mask_size());
mf.generate();
}
void OopMapCacheEntry::fill(const methodHandle& method, int bci) {
HandleMark hm;
// Flush entry to deallocate an existing entry
flush();
set_method(method());
set_bci(bci);
if (method->is_native()) {
// Native method activations have oops only among the parameters and one
// extra oop following the parameters (the mirror for static native methods).
fill_for_native(method);
} else {
EXCEPTION_MARK;
OopMapForCacheEntry gen(method, bci, this);
gen.compute_map(CATCH);
}
}
void OopMapCacheEntry::set_mask(CellTypeState *vars, CellTypeState *stack, int stack_top) {
// compute bit mask size
int max_locals = method()->max_locals();
int n_entries = max_locals + stack_top;
set_mask_size(n_entries * bits_per_entry);
allocate_bit_mask();
set_expression_stack_size(stack_top);
// compute bits
int word_index = 0;
uintptr_t value = 0;
uintptr_t mask = 1;
CellTypeState* cell = vars;
for (int entry_index = 0; entry_index < n_entries; entry_index++, mask <<= bits_per_entry, cell++) {
// store last word
if (mask == 0) {
bit_mask()[word_index++] = value;
value = 0;
mask = 1;
}
// switch to stack when done with locals
if (entry_index == max_locals) {
cell = stack;
}
// set oop bit
if ( cell->is_reference()) {
value |= (mask << oop_bit_number );
}
// set dead bit
if (!cell->is_live()) {
value |= (mask << dead_bit_number);
assert(!cell->is_reference(), "dead value marked as oop");
}
}
// make sure last word is stored
bit_mask()[word_index] = value;
// verify bit mask
assert(verify_mask(vars, stack, max_locals, stack_top), "mask could not be verified");
}
void OopMapCacheEntry::flush() {
deallocate_bit_mask();
initialize();
}
// Implementation of OopMapCache
void InterpreterOopMap::resource_copy(OopMapCacheEntry* from) {
assert(_resource_allocate_bit_mask,
"Should not resource allocate the _bit_mask");
set_method(from->method());
set_bci(from->bci());
set_mask_size(from->mask_size());
set_expression_stack_size(from->expression_stack_size());
// Is the bit mask contained in the entry?
if (from->mask_size() <= small_mask_limit) {
memcpy((void *)_bit_mask, (void *)from->_bit_mask,
mask_word_size() * BytesPerWord);
} else {
// The expectation is that this InterpreterOopMap is a recently created
// and empty. It is used to get a copy of a cached entry.
// If the bit mask has a value, it should be in the
// resource area.
assert(_bit_mask[0] == 0 ||
Thread::current()->resource_area()->contains((void*)_bit_mask[0]),
"The bit mask should have been allocated from a resource area");
// Allocate the bit_mask from a Resource area for performance. Allocating
// from the C heap as is done for OopMapCache has a significant
// performance impact.
_bit_mask[0] = (uintptr_t) NEW_RESOURCE_ARRAY(uintptr_t, mask_word_size());
assert(_bit_mask[0] != 0, "bit mask was not allocated");
memcpy((void*) _bit_mask[0], (void*) from->_bit_mask[0],
mask_word_size() * BytesPerWord);
}
}
inline unsigned int OopMapCache::hash_value_for(const methodHandle& method, int bci) const {
// We use method->code_size() rather than method->identity_hash() below since
// the mark may not be present if a pointer to the method is already reversed.
return ((unsigned int) bci)
^ ((unsigned int) method->max_locals() << 2)
^ ((unsigned int) method->code_size() << 4)
^ ((unsigned int) method->size_of_parameters() << 6);
}
OopMapCacheEntry* volatile OopMapCache::_old_entries = NULL;
OopMapCache::OopMapCache() {
_array = NEW_C_HEAP_ARRAY(OopMapCacheEntry*, _size, mtClass);
for(int i = 0; i < _size; i++) _array[i] = NULL;
}
OopMapCache::~OopMapCache() {
assert(_array != NULL, "sanity check");
// Deallocate oop maps that are allocated out-of-line
flush();
// Deallocate array
FREE_C_HEAP_ARRAY(OopMapCacheEntry*, _array);
}
OopMapCacheEntry* OopMapCache::entry_at(int i) const {
return OrderAccess::load_acquire(&(_array[i % _size]));
}
bool OopMapCache::put_at(int i, OopMapCacheEntry* entry, OopMapCacheEntry* old) {
return Atomic::cmpxchg(entry, &_array[i % _size], old) == old;
}
void OopMapCache::flush() {
for (int i = 0; i < _size; i++) {
OopMapCacheEntry* entry = _array[i];
if (entry != NULL) {
_array[i] = NULL; // no barrier, only called in OopMapCache destructor
entry->flush();
FREE_C_HEAP_OBJ(entry);
}
}
}
void OopMapCache::flush_obsolete_entries() {
assert(SafepointSynchronize::is_at_safepoint(), "called by RedefineClasses in a safepoint");
for (int i = 0; i < _size; i++) {
OopMapCacheEntry* entry = _array[i];
if (entry != NULL && !entry->is_empty() && entry->method()->is_old()) {
// Cache entry is occupied by an old redefined method and we don't want
// to pin it down so flush the entry.
if (log_is_enabled(Debug, redefine, class, oopmap)) {
ResourceMark rm;
log_debug(redefine, class, interpreter, oopmap)
("flush: %s(%s): cached entry @%d",
entry->method()->name()->as_C_string(), entry->method()->signature()->as_C_string(), i);
}
_array[i] = NULL;
entry->flush();
FREE_C_HEAP_OBJ(entry);
}
}
}
// Called by GC for thread root scan during a safepoint only. The other interpreted frame oopmaps
// are generated locally and not cached.
void OopMapCache::lookup(const methodHandle& method,
int bci,
InterpreterOopMap* entry_for) {
assert(SafepointSynchronize::is_at_safepoint(), "called by GC in a safepoint");
int probe = hash_value_for(method, bci);
int i;
OopMapCacheEntry* entry = NULL;
if (log_is_enabled(Debug, interpreter, oopmap)) {
static int count = 0;
ResourceMark rm;
log_debug(interpreter, oopmap)
("%d - Computing oopmap at bci %d for %s at hash %d", ++count, bci,
method()->name_and_sig_as_C_string(), probe);
}
// Search hashtable for match
for(i = 0; i < _probe_depth; i++) {
entry = entry_at(probe + i);
if (entry != NULL && !entry->is_empty() && entry->match(method, bci)) {
entry_for->resource_copy(entry);
assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
log_debug(interpreter, oopmap)("- found at hash %d", probe + i);
return;
}
}
// Entry is not in hashtable.
// Compute entry
OopMapCacheEntry* tmp = NEW_C_HEAP_OBJ(OopMapCacheEntry, mtClass);
tmp->initialize();
tmp->fill(method, bci);
entry_for->resource_copy(tmp);
if (method->should_not_be_cached()) {
// It is either not safe or not a good idea to cache this Method*
// at this time. We give the caller of lookup() a copy of the
// interesting info via parameter entry_for, but we don't add it to
// the cache. See the gory details in Method*.cpp.
FREE_C_HEAP_OBJ(tmp);
return;
}
// First search for an empty slot
for(i = 0; i < _probe_depth; i++) {
entry = entry_at(probe + i);
if (entry == NULL) {
if (put_at(probe + i, tmp, NULL)) {
assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
return;
}
}
}
log_debug(interpreter, oopmap)("*** collision in oopmap cache - flushing item ***");
// No empty slot (uncommon case). Use (some approximation of a) LRU algorithm
// where the first entry in the collision array is replaced with the new one.
OopMapCacheEntry* old = entry_at(probe + 0);
if (put_at(probe + 0, tmp, old)) {
enqueue_for_cleanup(old);
} else {
enqueue_for_cleanup(tmp);
}
assert(!entry_for->is_empty(), "A non-empty oop map should be returned");
return;
}
void OopMapCache::enqueue_for_cleanup(OopMapCacheEntry* entry) {
bool success = false;
OopMapCacheEntry* head;
do {
head = _old_entries;
entry->_next = head;
success = Atomic::cmpxchg(entry, &_old_entries, head) == head;
} while (!success);
if (log_is_enabled(Debug, interpreter, oopmap)) {
ResourceMark rm;
log_debug(interpreter, oopmap)("enqueue %s at bci %d for cleanup",
entry->method()->name_and_sig_as_C_string(), entry->bci());
}
}
// This is called after GC threads are done and nothing is accessing the old_entries
// list, so no synchronization needed.
void OopMapCache::cleanup_old_entries() {
OopMapCacheEntry* entry = _old_entries;
_old_entries = NULL;
while (entry != NULL) {
if (log_is_enabled(Debug, interpreter, oopmap)) {
ResourceMark rm;
log_debug(interpreter, oopmap)("cleanup entry %s at bci %d",
entry->method()->name_and_sig_as_C_string(), entry->bci());
}
OopMapCacheEntry* next = entry->_next;
entry->flush();
FREE_C_HEAP_OBJ(entry);
entry = next;
}
}
void OopMapCache::compute_one_oop_map(const methodHandle& method, int bci, InterpreterOopMap* entry) {
// Due to the invariants above it's tricky to allocate a temporary OopMapCacheEntry on the stack
OopMapCacheEntry* tmp = NEW_C_HEAP_ARRAY(OopMapCacheEntry, 1, mtClass);
tmp->initialize();
tmp->fill(method, bci);
entry->resource_copy(tmp);
FREE_C_HEAP_ARRAY(OopMapCacheEntry, tmp);
}