Mon, 23 Jun 2008 14:11:12 -0700
6708714: Optimize long LShift on 32-bits x86
Summary: For small (1-3 bits) left long shifts in 32-bits VM use sets of add+addc instructions instead of shld+shl on new AMD cpus.
Reviewed-by: never
Contributed-by: shrinivas.joshi@amd.com
duke@435 | 1 | /* |
duke@435 | 2 | * Copyright 2001-2002 Sun Microsystems, Inc. All Rights Reserved. |
duke@435 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
duke@435 | 4 | * |
duke@435 | 5 | * This code is free software; you can redistribute it and/or modify it |
duke@435 | 6 | * under the terms of the GNU General Public License version 2 only, as |
duke@435 | 7 | * published by the Free Software Foundation. |
duke@435 | 8 | * |
duke@435 | 9 | * This code is distributed in the hope that it will be useful, but WITHOUT |
duke@435 | 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
duke@435 | 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
duke@435 | 12 | * version 2 for more details (a copy is included in the LICENSE file that |
duke@435 | 13 | * accompanied this code). |
duke@435 | 14 | * |
duke@435 | 15 | * You should have received a copy of the GNU General Public License version |
duke@435 | 16 | * 2 along with this work; if not, write to the Free Software Foundation, |
duke@435 | 17 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
duke@435 | 18 | * |
duke@435 | 19 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
duke@435 | 20 | * CA 95054 USA or visit www.sun.com if you need additional information or |
duke@435 | 21 | * have any questions. |
duke@435 | 22 | * |
duke@435 | 23 | */ |
duke@435 | 24 | |
duke@435 | 25 | // ThreadCritical is used to protect short non-blocking critical sections. |
duke@435 | 26 | // This class must use no vm facilities that require initialization. |
duke@435 | 27 | // It is used very early in the vm's initialization, in allocation |
duke@435 | 28 | // code and other areas. ThreadCritical regions are reentrant. |
duke@435 | 29 | // |
duke@435 | 30 | // Due to race conditions during vm exit, some of the os level |
duke@435 | 31 | // synchronization primitives may not be deallocated at exit. It |
duke@435 | 32 | // is a good plan to implement the platform dependant sections of |
duke@435 | 33 | // code with resources that are recoverable during process |
duke@435 | 34 | // cleanup by the os. Calling the initialize method before use |
duke@435 | 35 | // is also problematic, it is best to use preinitialized primitives |
duke@435 | 36 | // if possible. As an example: |
duke@435 | 37 | // |
duke@435 | 38 | // mutex_t mp = DEFAULTMUTEX; |
duke@435 | 39 | // |
duke@435 | 40 | // Also note that this class is declared as a StackObj to enforce |
duke@435 | 41 | // block structured short locks. It cannot be declared a ResourceObj |
duke@435 | 42 | // or CHeapObj, due to initialization issues. |
duke@435 | 43 | |
duke@435 | 44 | class ThreadCritical : public StackObj { |
duke@435 | 45 | friend class os; |
duke@435 | 46 | private: |
duke@435 | 47 | static void initialize(); |
duke@435 | 48 | static void release(); |
duke@435 | 49 | |
duke@435 | 50 | public: |
duke@435 | 51 | ThreadCritical(); |
duke@435 | 52 | ~ThreadCritical(); |
duke@435 | 53 | }; |