d76606c25b2aedd6d9524909ae9759d2ee9fbb9d
[WebKit-https.git] / Source / JavaScriptCore / dfg / DFGUnificationPhase.cpp
1 /*
2  * Copyright (C) 2013, 2015 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,
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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 "DFGUnificationPhase.h"
28
29 #if ENABLE(DFG_JIT)
30
31 #include "DFGBasicBlockInlines.h"
32 #include "DFGGraph.h"
33 #include "DFGPhase.h"
34 #include "JSCInlines.h"
35
36 namespace JSC { namespace DFG {
37
38 class UnificationPhase : public Phase {
39 public:
40     UnificationPhase(Graph& graph)
41         : Phase(graph, "unification")
42     {
43     }
44     
45     bool run()
46     {
47         ASSERT(m_graph.m_form == ThreadedCPS);
48         ASSERT(m_graph.m_unificationState == LocallyUnified);
49         
50         // Ensure that all Phi functions are unified.
51         for (BlockIndex blockIndex = m_graph.numBlocks(); blockIndex--;) {
52             BasicBlock* block = m_graph.block(blockIndex);
53             if (!block)
54                 continue;
55             ASSERT(block->isReachable);
56             
57             for (unsigned phiIndex = block->phis.size(); phiIndex--;) {
58                 Node* phi = block->phis[phiIndex];
59                 for (unsigned childIdx = 0; childIdx < AdjacencyList::Size; ++childIdx) {
60                     if (!phi->children.child(childIdx))
61                         break;
62
63                     // We'd like to reverse the order of unification because it helps to reveal
64                     // more bugs on our end, though it's otherwise not observable. But we do it
65                     // this way because it works around a bug in open source LLVM's live-outs
66                     // computation.
67                     phi->variableAccessData()->unify(phi->children.child(childIdx)->variableAccessData());
68                 }
69             }
70         }
71         
72         // Ensure that all predictions are fixed up based on the unification.
73         for (unsigned i = 0; i < m_graph.m_variableAccessData.size(); ++i) {
74             VariableAccessData* data = &m_graph.m_variableAccessData[i];
75             data->find()->predict(data->nonUnifiedPrediction());
76             data->find()->mergeStructureCheckHoistingFailed(data->structureCheckHoistingFailed());
77             data->find()->mergeCheckArrayHoistingFailed(data->checkArrayHoistingFailed());
78             data->find()->mergeShouldNeverUnbox(data->shouldNeverUnbox());
79             data->find()->mergeIsLoadedFrom(data->isLoadedFrom());
80             data->find()->mergeIsProfitableToUnbox(data->isProfitableToUnbox());
81         }
82         
83         m_graph.m_unificationState = GloballyUnified;
84         return true;
85     }
86 };
87
88 bool performUnification(Graph& graph)
89 {
90     SamplingRegion samplingRegion("DFG Unification Phase");
91     return runPhase<UnificationPhase>(graph);
92 }
93
94 } } // namespace JSC::DFG
95
96 #endif // ENABLE(DFG_JIT)
97