1/*
2 * Copyright (C) 2011 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 "JSCellInlines.h"
34
35namespace JSC { namespace DFG {
36
37class VirtualRegisterAllocationPhase : public Phase {
38public:
39    VirtualRegisterAllocationPhase(Graph& graph)
40        : Phase(graph, "virtual register allocation")
41    {
42    }
43
44    bool run()
45    {
46#if DFG_ENABLE(DEBUG_VERBOSE)
47        dataLogF("Preserved vars: ");
48        m_graph.m_preservedVars.dump(WTF::dataFile());
49        dataLogF("\n");
50#endif
51        ScoreBoard scoreBoard(m_graph.m_preservedVars);
52        scoreBoard.assertClear();
53#if DFG_ENABLE(DEBUG_PROPAGATION_VERBOSE)
54        bool needsNewLine = false;
55#endif
56        for (size_t blockIndex = 0; blockIndex < m_graph.m_blocks.size(); ++blockIndex) {
57            BasicBlock* block = m_graph.m_blocks[blockIndex].get();
58            if (!block)
59                continue;
60            if (!block->isReachable)
61                continue;
62            for (size_t indexInBlock = 0; indexInBlock < block->size(); ++indexInBlock) {
63                Node* node = block->at(indexInBlock);
64#if DFG_ENABLE(DEBUG_PROPAGATION_VERBOSE)
65                if (needsNewLine)
66                    dataLogF("\n");
67                dataLogF("   @%u:", node->index());
68                needsNewLine = true;
69#endif
70
71                if (!node->shouldGenerate())
72                    continue;
73
74                switch (node->op()) {
75                case Phi:
76                case Flush:
77                case PhantomLocal:
78                    continue;
79                case GetLocal:
80                    ASSERT(!node->child1()->hasResult());
81                    break;
82                default:
83                    break;
84                }
85
86                // First, call use on all of the current node's children, then
87                // allocate a VirtualRegister for this node. We do so in this
88                // order so that if a child is on its last use, and a
89                // VirtualRegister is freed, then it may be reused for node.
90                if (node->flags() & NodeHasVarArgs) {
91                    for (unsigned childIdx = node->firstChild(); childIdx < node->firstChild() + node->numChildren(); childIdx++)
92                        scoreBoard.useIfHasResult(m_graph.m_varArgChildren[childIdx]);
93                } else {
94                    scoreBoard.useIfHasResult(node->child1());
95                    scoreBoard.useIfHasResult(node->child2());
96                    scoreBoard.useIfHasResult(node->child3());
97                }
98
99                if (!node->hasResult())
100                    continue;
101
102                VirtualRegister virtualRegister = scoreBoard.allocate();
103#if DFG_ENABLE(DEBUG_PROPAGATION_VERBOSE)
104                dataLogF(
105                    " Assigning virtual register %u to node %u.",
106                    virtualRegister, node->index());
107#endif
108                node->setVirtualRegister(virtualRegister);
109                // 'mustGenerate' nodes have their useCount artificially elevated,
110                // call use now to account for this.
111                if (node->mustGenerate())
112                    scoreBoard.use(node);
113            }
114            scoreBoard.assertClear();
115        }
116#if DFG_ENABLE(DEBUG_PROPAGATION_VERBOSE)
117        if (needsNewLine)
118            dataLogF("\n");
119#endif
120
121        // 'm_numCalleeRegisters' is the number of locals and temporaries allocated
122        // for the function (and checked for on entry). Since we perform a new and
123        // different allocation of temporaries, more registers may now be required.
124        unsigned calleeRegisters = scoreBoard.highWatermark() + m_graph.m_parameterSlots;
125        size_t inlineCallFrameCount = codeBlock()->inlineCallFrames().size();
126        for (size_t i = 0; i < inlineCallFrameCount; i++) {
127            InlineCallFrame& inlineCallFrame = codeBlock()->inlineCallFrames()[i];
128            CodeBlock* codeBlock = baselineCodeBlockForInlineCallFrame(&inlineCallFrame);
129            unsigned requiredCalleeRegisters = inlineCallFrame.stackOffset + codeBlock->m_numCalleeRegisters;
130            if (requiredCalleeRegisters > calleeRegisters)
131                calleeRegisters = requiredCalleeRegisters;
132        }
133        if ((unsigned)codeBlock()->m_numCalleeRegisters < calleeRegisters)
134            codeBlock()->m_numCalleeRegisters = calleeRegisters;
135#if DFG_ENABLE(DEBUG_VERBOSE)
136        dataLogF("Num callee registers: %u\n", calleeRegisters);
137#endif
138
139        return true;
140    }
141};
142
143bool performVirtualRegisterAllocation(Graph& graph)
144{
145    SamplingRegion samplingRegion("DFG Virtual Register Allocation Phase");
146    return runPhase<VirtualRegisterAllocationPhase>(graph);
147}
148
149} } // namespace JSC::DFG
150
151#endif // ENABLE(DFG_JIT)
152