1/*
2 * Copyright (C) 2013 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
30namespace JSC { namespace DFG {
31
32class BlockInsertionSet;
33class Graph;
34struct BasicBlock;
35
36// Inserts dummy basic blocks before any loop headers that don't already have
37// a single non-loop predecessor.
38
39bool performLoopPreHeaderCreation(Graph&);
40
41// Creates a new basic block (a pre-header) that jumps to the given block. All
42// predecessors of the given block that aren't dominated by it are rerouted to
43// the pre-header.
44//
45// This function is used internally and it's used in a surgical fashion by
46// OSREntrypointCreationPhase.
47//
48// Note that executing this function requires having an intact dominators
49// analysis. You should run that analysis before doing damage to the CFG, even
50// if said damage is done before you call this.
51BasicBlock* createPreHeader(Graph&, BlockInsertionSet&, BasicBlock*);
52
53} } // namespace JSC::DFG
54
55#endif // ENABLE(DFG_JIT)
56