1/*
2 * Copyright (C) 2011, 2014 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#pragma once
27
28#if ENABLE(DFG_JIT)
29
30#include "DFGCommon.h"
31
32namespace JSC { namespace DFG {
33
34class Graph;
35
36// Block-local common subexpression elimination. It uses clobberize() for heap
37// modeling, which is quite precise. This phase is known to produce big wins on
38// a few benchmarks, and is relatively cheap to run.
39//
40// Note that this phase also gets rid of Identity nodes, which means that it's
41// currently not an optional phase. Basically, DFG IR doesn't have use-lists,
42// so there is no instantaneous replaceAllUsesWith operation. Instead, you turn
43// a node into an Identity and wait for CSE to clean it up.
44bool performLocalCSE(Graph&);
45
46// Same, but global. Only works for SSA. This will find common subexpressions
47// both in the same block and in any block that dominates the current block. It
48// has no limits on how far it will look for load-elimination opportunities.
49bool performGlobalCSE(Graph&);
50
51} } // namespace JSC::DFG
52
53#endif // ENABLE(DFG_JIT)
54