Source/JavaScriptCore/dfg/DFGVirtualRegisterAllocationPhase.cpp

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