1 /*
   2  * Copyright (c) 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.ssi;
  24 
  25 import java.util.BitSet;
  26 
  27 import org.graalvm.compiler.core.common.cfg.AbstractBlockBase;
  28 import org.graalvm.compiler.debug.Debug;
  29 import org.graalvm.compiler.debug.GraalError;
  30 import org.graalvm.compiler.debug.Indent;
  31 import org.graalvm.compiler.lir.LIR;
  32 import org.graalvm.compiler.lir.StandardOp.BlockEndOp;
  33 import org.graalvm.compiler.lir.StandardOp.LabelOp;
  34 
  35 import jdk.vm.ci.meta.Value;
  36 
  37 public abstract class SSIBuilderBase {
  38 
  39     protected static final int LOG_LEVEL = Debug.INFO_LOG_LEVEL;
  40     protected final Value[] operands;
  41     protected final LIR lir;
  42 
  43     public SSIBuilderBase(LIR lir) {
  44         this.lir = lir;
  45         this.operands = new Value[lir.numVariables()];
  46     }
  47 
  48     protected LIR getLIR() {
  49         return lir;
  50     }
  51 
  52     abstract BitSet getLiveIn(AbstractBlockBase<?> block);
  53 
  54     abstract BitSet getLiveOut(AbstractBlockBase<?> block);
  55 
  56     public final void build() {
  57         buildIntern();
  58         // check that the liveIn set of the first block is empty
  59         AbstractBlockBase<?> startBlock = getLIR().getControlFlowGraph().getStartBlock();
  60         if (getLiveIn(startBlock).cardinality() != 0) {
  61             // bailout if this occurs in product mode.
  62             throw new GraalError("liveIn set of first block must be empty: " + getLiveIn(startBlock));
  63         }
  64     }
  65 
  66     protected abstract void buildIntern();
  67 
  68     @SuppressWarnings("try")
  69     public final void finish() {
  70         // iterate all blocks in reverse order
  71         for (AbstractBlockBase<?> block : (AbstractBlockBase<?>[]) lir.getControlFlowGraph().getBlocks()) {
  72             try (Indent indent = Debug.logAndIndent(LOG_LEVEL, "Finish Block %s", block)) {
  73                 // set label
  74                 buildOutgoing(block, getLiveOut(block));
  75                 buildIncoming(block, getLiveIn(block));
  76             }
  77         }
  78     }
  79 
  80     private void buildIncoming(AbstractBlockBase<?> block, BitSet liveIn) {
  81         /*
  82          * Collect live out of predecessors since there might be values not used in this block which
  83          * might cause out/in mismatch.
  84          */
  85         BitSet predLiveOut = new BitSet(liveIn.length());
  86         for (AbstractBlockBase<?> pred : block.getPredecessors()) {
  87             predLiveOut.or(getLiveOut(pred));
  88         }
  89         if (predLiveOut.isEmpty()) {
  90             return;
  91         }
  92 
  93         Value[] values = new Value[predLiveOut.cardinality()];
  94         assert values.length > 0;
  95         int cnt = 0;
  96         for (int i = predLiveOut.nextSetBit(0); i >= 0; i = predLiveOut.nextSetBit(i + 1)) {
  97             values[cnt++] = liveIn.get(i) ? operands[i] : Value.ILLEGAL;
  98         }
  99         LabelOp label = SSIUtil.incoming(getLIR(), block);
 100         label.addIncomingValues(values);
 101     }
 102 
 103     private void buildOutgoing(AbstractBlockBase<?> block, BitSet liveOut) {
 104         if (liveOut.isEmpty()) {
 105             return;
 106         }
 107         Value[] values = new Value[liveOut.cardinality()];
 108         assert values.length > 0;
 109         int cnt = 0;
 110         for (int i = liveOut.nextSetBit(0); i >= 0; i = liveOut.nextSetBit(i + 1)) {
 111             values[cnt++] = operands[i];
 112         }
 113         BlockEndOp blockEndOp = SSIUtil.outgoing(getLIR(), block);
 114         blockEndOp.addOutgoingValues(values);
 115     }
 116 }