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hotspot/src/share/vm/code/stubs.cpp

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+/*
+ * Copyright 1997-2005 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/_stubs.cpp.incl"
+
+
+// Implementation of StubQueue
+//
+// Standard wrap-around queue implementation; the queue dimensions
+// are specified by the _queue_begin & _queue_end indices. The queue
+// can be in two states (transparent to the outside):
+//
+// a) contiguous state: all queue entries in one block (or empty)
+//
+// Queue: |...|XXXXXXX|...............|
+//        ^0  ^begin  ^end            ^size = limit
+//            |_______|
+//            one block
+//
+// b) non-contiguous state: queue entries in two blocks
+//
+// Queue: |XXX|.......|XXXXXXX|.......|
+//        ^0  ^end    ^begin  ^limit  ^size
+//        |___|       |_______|
+//         1st block  2nd block
+//
+// In the non-contiguous state, the wrap-around point is
+// indicated via the _buffer_limit index since the last
+// queue entry may not fill up the queue completely in
+// which case we need to know where the 2nd block's end
+// is to do the proper wrap-around. When removing the
+// last entry of the 2nd block, _buffer_limit is reset
+// to _buffer_size.
+//
+// CAUTION: DO NOT MESS WITH THIS CODE IF YOU CANNOT PROVE
+// ITS CORRECTNESS! THIS CODE IS MORE SUBTLE THAN IT LOOKS!
+
+
+StubQueue::StubQueue(StubInterface* stub_interface, int buffer_size,
+                     Mutex* lock, const char* name) : _mutex(lock) {
+  intptr_t size = round_to(buffer_size, 2*BytesPerWord);
+  BufferBlob* blob = BufferBlob::create(name, size);
+  if( blob == NULL ) vm_exit_out_of_memory1(size, "CodeCache: no room for %s", name);
+  _stub_interface  = stub_interface;
+  _buffer_size     = blob->instructions_size();
+  _buffer_limit    = blob->instructions_size();
+  _stub_buffer     = blob->instructions_begin();
+  _queue_begin     = 0;
+  _queue_end       = 0;
+  _number_of_stubs = 0;
+  register_queue(this);
+}
+
+
+StubQueue::~StubQueue() {
+  // Note: Currently StubQueues are never destroyed so nothing needs to be done here.
+  //       If we want to implement the destructor, we need to release the BufferBlob
+  //       allocated in the constructor (i.e., we need to keep it around or look it
+  //       up via CodeCache::find_blob(...).
+  Unimplemented();
+}
+
+
+Stub* StubQueue::stub_containing(address pc) const {
+  if (contains(pc)) {
+    for (Stub* s = first(); s != NULL; s = next(s)) {
+      if (stub_contains(s, pc)) return s;
+    }
+  }
+  return NULL;
+}
+
+
+Stub* StubQueue::request_committed(int code_size) {
+  Stub* s = request(code_size);
+  if (s != NULL) commit(code_size);
+  return s;
+}
+
+
+Stub* StubQueue::request(int requested_code_size) {
+  assert(requested_code_size > 0, "requested_code_size must be > 0");
+  if (_mutex != NULL) _mutex->lock();
+  Stub* s = current_stub();
+  int requested_size = round_to(stub_code_size_to_size(requested_code_size), CodeEntryAlignment);
+  if (requested_size <= available_space()) {
+    if (is_contiguous()) {
+      // Queue: |...|XXXXXXX|.............|
+      //        ^0  ^begin  ^end          ^size = limit
+      assert(_buffer_limit == _buffer_size, "buffer must be fully usable");
+      if (_queue_end + requested_size <= _buffer_size) {
+        // code fits in at the end => nothing to do
+        stub_initialize(s, requested_size);
+        return s;
+      } else {
+        // stub doesn't fit in at the queue end
+        // => reduce buffer limit & wrap around
+        assert(!is_empty(), "just checkin'");
+        _buffer_limit = _queue_end;
+        _queue_end = 0;
+      }
+    }
+  }
+  if (requested_size <= available_space()) {
+    assert(!is_contiguous(), "just checkin'");
+    assert(_buffer_limit <= _buffer_size, "queue invariant broken");
+    // Queue: |XXX|.......|XXXXXXX|.......|
+    //        ^0  ^end    ^begin  ^limit  ^size
+    s = current_stub();
+    stub_initialize(s, requested_size);
+    return s;
+  }
+  // Not enough space left
+  if (_mutex != NULL) _mutex->unlock();
+  return NULL;
+}
+
+
+void StubQueue::commit(int committed_code_size) {
+  assert(committed_code_size > 0, "committed_code_size must be > 0");
+  int committed_size = round_to(stub_code_size_to_size(committed_code_size), CodeEntryAlignment);
+  Stub* s = current_stub();
+  assert(committed_size <= stub_size(s), "committed size must not exceed requested size");
+  stub_initialize(s, committed_size);
+  _queue_end += committed_size;
+  _number_of_stubs++;
+  if (_mutex != NULL) _mutex->unlock();
+  debug_only(stub_verify(s);)
+}
+
+
+void StubQueue::remove_first() {
+  if (number_of_stubs() == 0) return;
+  Stub* s = first();
+  debug_only(stub_verify(s);)
+  stub_finalize(s);
+  _queue_begin += stub_size(s);
+  assert(_queue_begin <= _buffer_limit, "sanity check");
+  if (_queue_begin == _queue_end) {
+    // buffer empty
+    // => reset queue indices
+    _queue_begin  = 0;
+    _queue_end    = 0;
+    _buffer_limit = _buffer_size;
+  } else if (_queue_begin == _buffer_limit) {
+    // buffer limit reached
+    // => reset buffer limit & wrap around
+    _buffer_limit = _buffer_size;
+    _queue_begin = 0;
+  }
+  _number_of_stubs--;
+}
+
+
+void StubQueue::remove_first(int n) {
+  int i = MIN2(n, number_of_stubs());
+  while (i-- > 0) remove_first();
+}
+
+
+void StubQueue::remove_all(){
+  debug_only(verify();)
+  remove_first(number_of_stubs());
+  assert(number_of_stubs() == 0, "sanity check");
+}
+
+
+enum { StubQueueLimit = 10 };  // there are only a few in the world
+static StubQueue* registered_stub_queues[StubQueueLimit];
+
+void StubQueue::register_queue(StubQueue* sq) {
+  for (int i = 0; i < StubQueueLimit; i++) {
+    if (registered_stub_queues[i] == NULL) {
+      registered_stub_queues[i] = sq;
+      return;
+    }
+  }
+  ShouldNotReachHere();
+}
+
+
+void StubQueue::queues_do(void f(StubQueue* sq)) {
+  for (int i = 0; i < StubQueueLimit; i++) {
+    if (registered_stub_queues[i] != NULL) {
+      f(registered_stub_queues[i]);
+    }
+  }
+}
+
+
+void StubQueue::stubs_do(void f(Stub* s)) {
+  debug_only(verify();)
+  MutexLockerEx lock(_mutex);
+  for (Stub* s = first(); s != NULL; s = next(s)) f(s);
+}
+
+
+void StubQueue::verify() {
+  // verify only if initialized
+  if (_stub_buffer == NULL) return;
+  MutexLockerEx lock(_mutex);
+  // verify index boundaries
+  guarantee(0 <= _buffer_size, "buffer size must be positive");
+  guarantee(0 <= _buffer_limit && _buffer_limit <= _buffer_size , "_buffer_limit out of bounds");
+  guarantee(0 <= _queue_begin  && _queue_begin  <  _buffer_limit, "_queue_begin out of bounds");
+  guarantee(0 <= _queue_end    && _queue_end    <= _buffer_limit, "_queue_end   out of bounds");
+  // verify alignment
+  guarantee(_buffer_size  % CodeEntryAlignment == 0, "_buffer_size  not aligned");
+  guarantee(_buffer_limit % CodeEntryAlignment == 0, "_buffer_limit not aligned");
+  guarantee(_queue_begin  % CodeEntryAlignment == 0, "_queue_begin  not aligned");
+  guarantee(_queue_end    % CodeEntryAlignment == 0, "_queue_end    not aligned");
+  // verify buffer limit/size relationship
+  if (is_contiguous()) {
+    guarantee(_buffer_limit == _buffer_size, "_buffer_limit must equal _buffer_size");
+  }
+  // verify contents
+  int n = 0;
+  for (Stub* s = first(); s != NULL; s = next(s)) {
+    stub_verify(s);
+    n++;
+  }
+  guarantee(n == number_of_stubs(), "number of stubs inconsistent");
+  guarantee(_queue_begin != _queue_end || n == 0, "buffer indices must be the same");
+}
+
+
+void StubQueue::print() {
+  MutexLockerEx lock(_mutex);
+  for (Stub* s = first(); s != NULL; s = next(s)) {
+    stub_print(s);
+  }
+}