1 /*
   2  * Copyright (c) 2015, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 package org.graalvm.compiler.lir.alloc.lsra.ssa;
  24 
  25 import static org.graalvm.compiler.lir.LIRValueUtil.asConstant;
  26 import static org.graalvm.compiler.lir.LIRValueUtil.isConstantValue;
  27 import static org.graalvm.compiler.lir.LIRValueUtil.isStackSlotValue;
  28 import static jdk.vm.ci.code.ValueUtil.isRegister;
  29 
  30 import java.util.List;
  31 
  32 import org.graalvm.compiler.core.common.cfg.AbstractBlockBase;
  33 import org.graalvm.compiler.debug.Debug;
  34 import org.graalvm.compiler.debug.DebugCounter;
  35 import org.graalvm.compiler.lir.LIRInstruction;
  36 import org.graalvm.compiler.lir.alloc.lsra.Interval;
  37 import org.graalvm.compiler.lir.alloc.lsra.LinearScan;
  38 import org.graalvm.compiler.lir.alloc.lsra.LinearScanResolveDataFlowPhase;
  39 import org.graalvm.compiler.lir.alloc.lsra.MoveResolver;
  40 import org.graalvm.compiler.lir.ssa.SSAUtil;
  41 import org.graalvm.compiler.lir.ssa.SSAUtil.PhiValueVisitor;
  42 
  43 import jdk.vm.ci.meta.Value;
  44 
  45 class SSALinearScanResolveDataFlowPhase extends LinearScanResolveDataFlowPhase {
  46 
  47     private static final DebugCounter numPhiResolutionMoves = Debug.counter("SSA LSRA[numPhiResolutionMoves]");
  48     private static final DebugCounter numStackToStackMoves = Debug.counter("SSA LSRA[numStackToStackMoves]");
  49 
  50     SSALinearScanResolveDataFlowPhase(LinearScan allocator) {
  51         super(allocator);
  52     }
  53 
  54     @Override
  55     protected void resolveCollectMappings(AbstractBlockBase<?> fromBlock, AbstractBlockBase<?> toBlock, AbstractBlockBase<?> midBlock, MoveResolver moveResolver) {
  56         super.resolveCollectMappings(fromBlock, toBlock, midBlock, moveResolver);
  57 
  58         if (toBlock.getPredecessorCount() > 1) {
  59             int toBlockFirstInstructionId = allocator.getFirstLirInstructionId(toBlock);
  60             int fromBlockLastInstructionId = allocator.getLastLirInstructionId(fromBlock) + 1;
  61 
  62             AbstractBlockBase<?> phiOutBlock = midBlock != null ? midBlock : fromBlock;
  63             List<LIRInstruction> instructions = allocator.getLIR().getLIRforBlock(phiOutBlock);
  64             int phiOutIdx = SSAUtil.phiOutIndex(allocator.getLIR(), phiOutBlock);
  65             int phiOutId = midBlock != null ? fromBlockLastInstructionId : instructions.get(phiOutIdx).id();
  66             assert phiOutId >= 0;
  67 
  68             PhiValueVisitor visitor = new PhiValueVisitor() {
  69 
  70                 @Override
  71                 public void visit(Value phiIn, Value phiOut) {
  72                     assert !isRegister(phiOut) : "phiOut is a register: " + phiOut;
  73                     assert !isRegister(phiIn) : "phiIn is a register: " + phiIn;
  74                     Interval toInterval = allocator.splitChildAtOpId(allocator.intervalFor(phiIn), toBlockFirstInstructionId, LIRInstruction.OperandMode.DEF);
  75                     if (isConstantValue(phiOut)) {
  76                         numPhiResolutionMoves.increment();
  77                         moveResolver.addMapping(asConstant(phiOut), toInterval);
  78                     } else {
  79                         Interval fromInterval = allocator.splitChildAtOpId(allocator.intervalFor(phiOut), phiOutId, LIRInstruction.OperandMode.DEF);
  80                         if (fromInterval != toInterval && !fromInterval.location().equals(toInterval.location())) {
  81                             numPhiResolutionMoves.increment();
  82                             if (!(isStackSlotValue(toInterval.location()) && isStackSlotValue(fromInterval.location()))) {
  83                                 moveResolver.addMapping(fromInterval, toInterval);
  84                             } else {
  85                                 numStackToStackMoves.increment();
  86                                 moveResolver.addMapping(fromInterval, toInterval);
  87                             }
  88                         }
  89                     }
  90                 }
  91             };
  92 
  93             SSAUtil.forEachPhiValuePair(allocator.getLIR(), toBlock, phiOutBlock, visitor);
  94             SSAUtil.removePhiOut(allocator.getLIR(), phiOutBlock);
  95         }
  96     }
  97 
  98 }