1/*
2 * Copyright (C) 2011, 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#include "config.h"
27#include "DFGVirtualRegisterAllocationPhase.h"
28
29#if ENABLE(DFG_JIT)
30
31#include "DFGGraph.h"
32#include "DFGScoreBoard.h"
33#include "JSCInlines.h"
34#include "StackAlignment.h"
35#include <wtf/StdLibExtras.h>
36
37namespace JSC { namespace DFG {
38
39class VirtualRegisterAllocationPhase : public Phase {
40public:
41    VirtualRegisterAllocationPhase(Graph& graph)
42        : Phase(graph, "virtual register allocation")
43    {
44    }
45
46    bool run()
47    {
48        ScoreBoard scoreBoard(m_graph.m_nextMachineLocal);
49        scoreBoard.assertClear();
50        for (size_t blockIndex = 0; blockIndex < m_graph.numBlocks(); ++blockIndex) {
51            BasicBlock* block = m_graph.block(blockIndex);
52            if (!block)
53                continue;
54            if (!block->isReachable)
55                continue;
56            for (size_t indexInBlock = 0; indexInBlock < block->size(); ++indexInBlock) {
57                Node* node = block->at(indexInBlock);
58
59                if (!node->shouldGenerate())
60                    continue;
61
62                switch (node->op()) {
63                case Phi:
64                case Flush:
65                case PhantomLocal:
66                    continue;
67                case GetLocal:
68                    ASSERT(!node->child1()->hasResult());
69                    break;
70                default:
71                    break;
72                }
73
74                // First, call use on all of the current node's children, then
75                // allocate a VirtualRegister for this node. We do so in this
76                // order so that if a child is on its last use, and a
77                // VirtualRegister is freed, then it may be reused for node.
78                if (node->flags() & NodeHasVarArgs) {
79                    for (unsigned childIdx = node->firstChild(); childIdx < node->firstChild() + node->numChildren(); childIdx++)
80                        scoreBoard.useIfHasResult(m_graph.m_varArgChildren[childIdx]);
81                } else {
82                    scoreBoard.useIfHasResult(node->child1());
83                    scoreBoard.useIfHasResult(node->child2());
84                    scoreBoard.useIfHasResult(node->child3());
85                }
86
87                if (!node->hasResult())
88                    continue;
89
90                VirtualRegister virtualRegister = scoreBoard.allocate();
91                node->setVirtualRegister(virtualRegister);
92                // 'mustGenerate' nodes have their useCount artificially elevated,
93                // call use now to account for this.
94                if (node->mustGenerate())
95                    scoreBoard.use(node);
96            }
97            scoreBoard.assertClear();
98        }
99
100        // Record the number of virtual registers we're using. This is used by calls
101        // to figure out where to put the parameters.
102        m_graph.m_nextMachineLocal = scoreBoard.highWatermark();
103
104        return true;
105    }
106};
107
108bool performVirtualRegisterAllocation(Graph& graph)
109{
110    SamplingRegion samplingRegion("DFG Virtual Register Allocation Phase");
111    return runPhase<VirtualRegisterAllocationPhase>(graph);
112}
113
114} } // namespace JSC::DFG
115
116#endif // ENABLE(DFG_JIT)
117