1 /*

     2  * Copyright (c) 2018, 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 

    24 

    25 package org.graalvm.compiler.lir.alloc.trace;

    26 

    27 import static org.graalvm.compiler.lir.LIRValueUtil.asVariable;

    28 import static org.graalvm.compiler.lir.LIRValueUtil.isVariable;

    29 import static org.graalvm.compiler.lir.alloc.trace.TraceUtil.isTrivialTrace;

    30 

    31 import java.util.Arrays;

    32 import java.util.EnumSet;

    33 

    34 import org.graalvm.compiler.core.common.alloc.Trace;

    35 import org.graalvm.compiler.core.common.cfg.AbstractBlockBase;

    36 import org.graalvm.compiler.lir.LIR;

    37 import org.graalvm.compiler.lir.LIRInstruction;

    38 import org.graalvm.compiler.lir.LIRInstruction.OperandFlag;

    39 import org.graalvm.compiler.lir.LIRInstruction.OperandMode;

    40 import org.graalvm.compiler.lir.StandardOp.JumpOp;

    41 import org.graalvm.compiler.lir.StandardOp.LabelOp;

    42 import org.graalvm.compiler.lir.ValueProcedure;

    43 import org.graalvm.compiler.lir.gen.LIRGenerationResult;

    44 import org.graalvm.compiler.lir.ssa.SSAUtil;

    45 

    46 import jdk.vm.ci.code.TargetDescription;

    47 import jdk.vm.ci.meta.Value;

    48 

    49 /**

    50  * Allocates a trivial trace i.e. a trace consisting of a single block with no instructions other

    51  * than the {@link LabelOp} and the {@link JumpOp}.

    52  */

    53 public final class TrivialTraceAllocator extends TraceAllocationPhase<TraceAllocationPhase.TraceAllocationContext> {

    54 

    55     @Override

    56     protected void run(TargetDescription target, LIRGenerationResult lirGenRes, Trace trace, TraceAllocationContext context) {

    57         LIR lir = lirGenRes.getLIR();

    58         assert isTrivialTrace(lir, trace) : "Not a trivial trace! " + trace;

    59         AbstractBlockBase<?> block = trace.getBlocks()[0];

    60         assert TraceAssertions.singleHeadPredecessor(trace) : "Trace head with more than one predecessor?!" + trace;

    61         AbstractBlockBase<?> pred = block.getPredecessors()[0];

    62 

    63         GlobalLivenessInfo livenessInfo = context.livenessInfo;

    64         allocate(block, pred, livenessInfo, SSAUtil.phiOutOrNull(lir, block));

    65     }

    66 

    67     public static void allocate(AbstractBlockBase<?> block, AbstractBlockBase<?> pred, GlobalLivenessInfo livenessInfo, LIRInstruction jump) {

    68         // exploit that the live sets are sorted

    69         assert TraceAssertions.liveSetsAreSorted(livenessInfo, block);

    70         assert TraceAssertions.liveSetsAreSorted(livenessInfo, pred);

    71 

    72         // setup incoming variables/locations

    73         final int[] blockIn = livenessInfo.getBlockIn(block);

    74         final Value[] predLocOut = livenessInfo.getOutLocation(pred);

    75         int inLenght = blockIn.length;

    76 

    77         // setup outgoing variables/locations

    78         final int[] blockOut = livenessInfo.getBlockOut(block);

    79         int outLength = blockOut.length;

    80         final Value[] locationOut = new Value[outLength];

    81 

    82         assert outLength <= inLenght : "Trivial Trace! There cannot be more outgoing values than incoming.";

    83         for (int outIdx = 0, inIdx = 0; outIdx < outLength; inIdx++) {

    84             if (blockOut[outIdx] == blockIn[inIdx]) {

    85                 // set the outgoing location to the incoming value

    86                 locationOut[outIdx++] = predLocOut[inIdx];

    87             }

    88         }

    89 

    90         /*

    91          * Since we do not change any of the location we can just use the outgoing of the

    92          * predecessor.

    93          */

    94         livenessInfo.setInLocations(block, predLocOut);

    95         livenessInfo.setOutLocations(block, locationOut);

    96         if (jump != null) {

    97             handlePhiOut(jump, blockIn, predLocOut);

    98         }

    99     }

   100 

   101     private static void handlePhiOut(LIRInstruction jump, int[] varIn, Value[] locIn) {

   102         // handle outgoing phi values

   103         ValueProcedure outputConsumer = new ValueProcedure() {

   104             @Override

   105             public Value doValue(Value value, OperandMode mode, EnumSet<OperandFlag> flags) {

   106                 if (isVariable(value)) {

   107                     // since incoming variables are sorted, we can do a binary search

   108                     return locIn[Arrays.binarySearch(varIn, asVariable(value).index)];

   109                 }

   110                 return value;

   111             }

   112         };

   113 

   114         // Jumps have only alive values (outgoing phi values)

   115         jump.forEachAlive(outputConsumer);

   116     }

   117 

   118 }