1798N/A * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved. 1798N/A * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 1798N/A * This code is free software; you can redistribute it and/or modify it 1798N/A * under the terms of the GNU General Public License version 2 only, as 1798N/A * published by the Free Software Foundation. 1798N/A * This code is distributed in the hope that it will be useful, but WITHOUT 1798N/A * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 1798N/A * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 1798N/A * version 2 for more details (a copy is included in the LICENSE file that 1798N/A * You should have received a copy of the GNU General Public License version 1798N/A * 2 along with this work; if not, write to the Free Software Foundation, 1798N/A * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 1798N/A * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 1798N/A // Check to see if we need to inflate the lock. This is only needed 1798N/A // if an object is locked using "this" lightweight monitor. In that 1798N/A // case, the displaced_header() is unlocked, because the 1798N/A // displaced_header() contains the header for the originally unlocked 1798N/A // object. However the object could have already been inflated. But it 1798N/A // does not matter, the inflation will just a no-op. For other cases, 1798N/A // the displaced header will be either 0x0 or 0x3, which are location 1798N/A // independent, therefore the BasicLock is free to move. 1798N/A // During OSR we may need to relocate a BasicLock (which contains a 1798N/A // displaced word) from a location in an interpreter frame to a 1798N/A // new location in a compiled frame. "this" refers to the source 1798N/A // basiclock in the interpreter frame. "dest" refers to the destination 1798N/A // basiclock in the new compiled frame. We *always* inflate in move_to(). 1798N/A // The always-Inflate policy works properly, but in 1.5.0 it can sometimes 1798N/A // cause performance problems in code that makes heavy use of a small # of 1798N/A // uncontended locks. (We'd inflate during OSR, and then sync performance 1798N/A // would subsequently plummet because the thread would be forced thru the slow-path). 1798N/A // This problem has been made largely moot on IA32 by inlining the inflated fast-path 1798N/A // operations in Fast_Lock and Fast_Unlock in i486.ad. 1798N/A // Note that there is a way to safely swing the object's markword from 1798N/A // one stack location to another. This avoids inflation. Obviously, 1798N/A // we need to ensure that both locations refer to the current thread's stack. 1798N/A // There are some subtle concurrency issues, however, and since the benefit is 1798N/A // is small (given the support for inflated fast-path locking in the fast_lock, etc) 1798N/A // we'll leave that optimization for another time. 1798N/A // WARNING: We can not put check here, because the inflation 1798N/A // will not update the displaced header. Once BasicLock is inflated, 1798N/A // no one should ever look at its content. 1798N/A // Typically the displaced header will be 0 (recursive stack lock) or 1798N/A // unused_mark. Naively we'd like to assert that the displaced mark 1798N/A // value is either 0, neutral, or 3. But with the advent of the 1798N/A // we can find any flavor mark in the displaced mark. 1798N/A// [RGV] The next line appears to do nothing!