1 /*
   2  * Copyright (c) 2015, 2016, 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.trace;
  24 
  25 import static org.graalvm.compiler.lir.LIRValueUtil.asVariable;
  26 import static org.graalvm.compiler.lir.LIRValueUtil.isVariable;
  27 import static org.graalvm.compiler.lir.alloc.trace.TraceUtil.isTrivialTrace;
  28 
  29 import java.util.EnumSet;
  30 
  31 import org.graalvm.compiler.core.common.alloc.Trace;
  32 import org.graalvm.compiler.core.common.alloc.TraceBuilderResult;
  33 import org.graalvm.compiler.core.common.cfg.AbstractBlockBase;
  34 import org.graalvm.compiler.lir.LIR;
  35 import org.graalvm.compiler.lir.LIRInstruction.OperandFlag;
  36 import org.graalvm.compiler.lir.LIRInstruction.OperandMode;
  37 import org.graalvm.compiler.lir.StandardOp.JumpOp;
  38 import org.graalvm.compiler.lir.StandardOp.LabelOp;
  39 import org.graalvm.compiler.lir.ValueProcedure;
  40 import org.graalvm.compiler.lir.gen.LIRGenerationResult;
  41 import org.graalvm.compiler.lir.ssa.SSAUtil;
  42 
  43 import jdk.vm.ci.code.TargetDescription;
  44 import jdk.vm.ci.meta.Value;
  45 
  46 /**
  47  * Allocates a trivial trace i.e. a trace consisting of a single block with no instructions other
  48  * than the {@link LabelOp} and the {@link JumpOp}.
  49  */
  50 final class TrivialTraceAllocator extends TraceAllocationPhase<TraceAllocationPhase.TraceAllocationContext> {
  51 
  52     @Override
  53     protected void run(TargetDescription target, LIRGenerationResult lirGenRes, Trace trace, TraceAllocationContext context) {
  54         LIR lir = lirGenRes.getLIR();
  55         TraceBuilderResult resultTraces = context.resultTraces;
  56         assert isTrivialTrace(lir, trace) : "Not a trivial trace! " + trace;
  57         AbstractBlockBase<?> block = trace.getBlocks()[0];
  58 
  59         AbstractBlockBase<?> pred = TraceUtil.getBestTraceInterPredecessor(resultTraces, block);
  60 
  61         Value[] variableMap = new Value[lir.numVariables()];
  62         GlobalLivenessInfo livenessInfo = context.livenessInfo;
  63         collectMapping(block, pred, livenessInfo, variableMap);
  64         assignLocations(lir, block, livenessInfo, variableMap);
  65     }
  66 
  67     /**
  68      * Collects the mapping from variable to location. Additionally the
  69      * {@link GlobalLivenessInfo#setInLocations incoming location array} is set.
  70      */
  71     private static void collectMapping(AbstractBlockBase<?> block, AbstractBlockBase<?> pred, GlobalLivenessInfo livenessInfo, Value[] variableMap) {
  72         final int[] blockIn = livenessInfo.getBlockIn(block);
  73         final Value[] predLocOut = livenessInfo.getOutLocation(pred);
  74         final Value[] locationIn = new Value[blockIn.length];
  75         for (int i = 0; i < blockIn.length; i++) {
  76             int varNum = blockIn[i];
  77             if (varNum >= 0) {
  78                 Value location = predLocOut[i];
  79                 variableMap[varNum] = location;
  80                 locationIn[i] = location;
  81             } else {
  82                 locationIn[i] = Value.ILLEGAL;
  83             }
  84         }
  85         livenessInfo.setInLocations(block, locationIn);
  86     }
  87 
  88     /**
  89      * Assigns the outgoing locations according to the {@link #collectMapping variable mapping}.
  90      */
  91     private static void assignLocations(LIR lir, AbstractBlockBase<?> block, GlobalLivenessInfo livenessInfo, Value[] variableMap) {
  92         final int[] blockOut = livenessInfo.getBlockOut(block);
  93         final Value[] locationOut = new Value[blockOut.length];
  94         for (int i = 0; i < blockOut.length; i++) {
  95             int varNum = blockOut[i];
  96             locationOut[i] = variableMap[varNum];
  97         }
  98         livenessInfo.setOutLocations(block, locationOut);
  99 
 100         // handle outgoing phi values
 101         ValueProcedure outputConsumer = new ValueProcedure() {
 102             @Override
 103             public Value doValue(Value value, OperandMode mode, EnumSet<OperandFlag> flags) {
 104                 if (isVariable(value)) {
 105                     return variableMap[asVariable(value).index];
 106                 }
 107                 return value;
 108             }
 109         };
 110 
 111         JumpOp jump = SSAUtil.phiOut(lir, block);
 112         // Jumps have only alive values (outgoing phi values)
 113         jump.forEachAlive(outputConsumer);
 114     }
 115 
 116 }