Mercurial > hg > graal-jvmci-8
view src/share/vm/runtime/basicLock.cpp @ 2607:008adfd6d850
Fixed the stateBefore of invokes and monitorenter instructions to include the arguments of the instruction.
This is necessary to ensure correct continuation in the interpreter when the stateBefore is used as a deoptimization point.
author | Thomas Wuerthinger <thomas@wuerthinger.net> |
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date | Fri, 06 May 2011 17:47:17 +0200 |
parents | f95d63e2154a |
children | 6e8e0bf87bbe |
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/* * Copyright (c) 1997, 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 "runtime/basicLock.hpp" #include "runtime/synchronizer.hpp" void BasicLock::print_on(outputStream* st) const { st->print("monitor"); } void BasicLock::move_to(oop obj, BasicLock* dest) { // Check to see if we need to inflate the lock. This is only needed // if an object is locked using "this" lightweight monitor. In that // case, the displaced_header() is unlocked, because the // displaced_header() contains the header for the originally unlocked // object. However the object could have already been inflated. But it // does not matter, the inflation will just a no-op. For other cases, // the displaced header will be either 0x0 or 0x3, which are location // independent, therefore the BasicLock is free to move. // // During OSR we may need to relocate a BasicLock (which contains a // displaced word) from a location in an interpreter frame to a // new location in a compiled frame. "this" refers to the source // basiclock in the interpreter frame. "dest" refers to the destination // basiclock in the new compiled frame. We *always* inflate in move_to(). // The always-Inflate policy works properly, but in 1.5.0 it can sometimes // cause performance problems in code that makes heavy use of a small # of // uncontended locks. (We'd inflate during OSR, and then sync performance // would subsequently plummet because the thread would be forced thru the slow-path). // This problem has been made largely moot on IA32 by inlining the inflated fast-path // operations in Fast_Lock and Fast_Unlock in i486.ad. // // Note that there is a way to safely swing the object's markword from // one stack location to another. This avoids inflation. Obviously, // we need to ensure that both locations refer to the current thread's stack. // There are some subtle concurrency issues, however, and since the benefit is // is small (given the support for inflated fast-path locking in the fast_lock, etc) // we'll leave that optimization for another time. if (displaced_header()->is_neutral()) { ObjectSynchronizer::inflate_helper(obj); // WARNING: We can not put check here, because the inflation // will not update the displaced header. Once BasicLock is inflated, // no one should ever look at its content. } else { // Typically the displaced header will be 0 (recursive stack lock) or // unused_mark. Naively we'd like to assert that the displaced mark // value is either 0, neutral, or 3. But with the advent of the // store-before-CAS avoidance in fast_lock/compiler_lock_object // we can find any flavor mark in the displaced mark. } // [RGV] The next line appears to do nothing! intptr_t dh = (intptr_t) displaced_header(); dest->set_displaced_header(displaced_header()); }