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