001/*
002 * Copyright (c) 2015, 2015, Oracle and/or its affiliates. All rights reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation.
008 *
009 * This code is distributed in the hope that it will be useful, but WITHOUT
010 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
011 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
012 * version 2 for more details (a copy is included in the LICENSE file that
013 * accompanied this code).
014 *
015 * You should have received a copy of the GNU General Public License version
016 * 2 along with this work; if not, write to the Free Software Foundation,
017 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
018 *
019 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
020 * or visit www.oracle.com if you need additional information or have any
021 * questions.
022 */
023package com.oracle.graal.lir.alloc.lsra;
024
025import static com.oracle.graal.compiler.common.GraalOptions.*;
026import static com.oracle.graal.lir.LIRValueUtil.*;
027import static jdk.internal.jvmci.code.ValueUtil.*;
028
029import java.util.*;
030
031import jdk.internal.jvmci.code.*;
032import com.oracle.graal.debug.*;
033import jdk.internal.jvmci.meta.*;
034
035import com.oracle.graal.compiler.common.alloc.*;
036import com.oracle.graal.compiler.common.cfg.*;
037import com.oracle.graal.lir.*;
038import com.oracle.graal.lir.LIRInstruction.OperandFlag;
039import com.oracle.graal.lir.LIRInstruction.OperandMode;
040import com.oracle.graal.lir.StandardOp.MoveOp;
041import com.oracle.graal.lir.gen.*;
042import com.oracle.graal.lir.gen.LIRGeneratorTool.SpillMoveFactory;
043import com.oracle.graal.lir.phases.*;
044
045/**
046 * Phase 7: Assign register numbers back to LIR.
047 */
048public final class LinearScanAssignLocationsPhase extends AllocationPhase {
049
050    private final LinearScan allocator;
051
052    LinearScanAssignLocationsPhase(LinearScan allocator) {
053        this.allocator = allocator;
054    }
055
056    @Override
057    protected <B extends AbstractBlockBase<B>> void run(TargetDescription target, LIRGenerationResult lirGenRes, List<B> codeEmittingOrder, List<B> linearScanOrder, SpillMoveFactory spillMoveFactory,
058                    RegisterAllocationConfig registerAllocationConfig) {
059        assignLocations();
060    }
061
062    /**
063     * Assigns the allocated location for an LIR instruction operand back into the instruction.
064     *
065     * @param operand an LIR instruction operand
066     * @param opId the id of the LIR instruction using {@code operand}
067     * @param mode the usage mode for {@code operand} by the instruction
068     * @return the location assigned for the operand
069     */
070    private Value colorLirOperand(Variable operand, int opId, OperandMode mode) {
071        Interval interval = allocator.intervalFor(operand);
072        assert interval != null : "interval must exist";
073
074        if (opId != -1) {
075            if (DetailedAsserts.getValue()) {
076                AbstractBlockBase<?> block = allocator.blockForId(opId);
077                if (block.getSuccessorCount() <= 1 && opId == allocator.getLastLirInstructionId(block)) {
078                    /*
079                     * Check if spill moves could have been appended at the end of this block, but
080                     * before the branch instruction. So the split child information for this branch
081                     * would be incorrect.
082                     */
083                    LIRInstruction instr = allocator.getLIR().getLIRforBlock(block).get(allocator.getLIR().getLIRforBlock(block).size() - 1);
084                    if (instr instanceof StandardOp.JumpOp) {
085                        if (allocator.getBlockData(block).liveOut.get(allocator.operandNumber(operand))) {
086                            assert false : String.format(
087                                            "can't get split child for the last branch of a block because the information would be incorrect (moves are inserted before the branch in resolveDataFlow) block=%s, instruction=%s, operand=%s",
088                                            block, instr, operand);
089                        }
090                    }
091                }
092            }
093
094            /*
095             * Operands are not changed when an interval is split during allocation, so search the
096             * right interval here.
097             */
098            interval = allocator.splitChildAtOpId(interval, opId, mode);
099        }
100
101        if (isIllegal(interval.location()) && interval.canMaterialize()) {
102            assert mode != OperandMode.DEF;
103            return interval.getMaterializedValue();
104        }
105        return interval.location();
106    }
107
108    /**
109     * @param op
110     * @param operand
111     * @param valueMode
112     * @param flags
113     * @see InstructionValueProcedure#doValue(LIRInstruction, Value, OperandMode, EnumSet)
114     */
115    private Value debugInfoProcedure(LIRInstruction op, Value operand, OperandMode valueMode, EnumSet<OperandFlag> flags) {
116        if (isVirtualStackSlot(operand)) {
117            return operand;
118        }
119        int tempOpId = op.id();
120        OperandMode mode = OperandMode.USE;
121        AbstractBlockBase<?> block = allocator.blockForId(tempOpId);
122        if (block.getSuccessorCount() == 1 && tempOpId == allocator.getLastLirInstructionId(block)) {
123            /*
124             * Generating debug information for the last instruction of a block. If this instruction
125             * is a branch, spill moves are inserted before this branch and so the wrong operand
126             * would be returned (spill moves at block boundaries are not considered in the live
127             * ranges of intervals).
128             * 
129             * Solution: use the first opId of the branch target block instead.
130             */
131            final LIRInstruction instr = allocator.getLIR().getLIRforBlock(block).get(allocator.getLIR().getLIRforBlock(block).size() - 1);
132            if (instr instanceof StandardOp.JumpOp) {
133                if (allocator.getBlockData(block).liveOut.get(allocator.operandNumber(operand))) {
134                    tempOpId = allocator.getFirstLirInstructionId(block.getSuccessors().iterator().next());
135                    mode = OperandMode.DEF;
136                }
137            }
138        }
139
140        /*
141         * Get current location of operand. The operand must be live because debug information is
142         * considered when building the intervals if the interval is not live, colorLirOperand will
143         * cause an assert on failure.
144         */
145        Value result = colorLirOperand((Variable) operand, tempOpId, mode);
146        assert !allocator.hasCall(tempOpId) || isStackSlotValue(result) || isConstant(result) || !allocator.isCallerSave(result) : "cannot have caller-save register operands at calls";
147        return result;
148    }
149
150    private void computeDebugInfo(final LIRInstruction op, LIRFrameState info) {
151        info.forEachState(op, this::debugInfoProcedure);
152    }
153
154    private void assignLocations(List<LIRInstruction> instructions) {
155        int numInst = instructions.size();
156        boolean hasDead = false;
157
158        InstructionValueProcedure assignProc = (op, operand, mode, flags) -> isVariable(operand) ? colorLirOperand((Variable) operand, op.id(), mode) : operand;
159        for (int j = 0; j < numInst; j++) {
160            final LIRInstruction op = instructions.get(j);
161            if (op == null) {
162                /*
163                 * this can happen when spill-moves are removed in eliminateSpillMoves
164                 */
165                hasDead = true;
166                continue;
167            }
168
169            // remove useless moves
170            MoveOp move = null;
171            if (op instanceof MoveOp) {
172                move = (MoveOp) op;
173                AllocatableValue result = move.getResult();
174                if (isVariable(result) && allocator.isMaterialized(result, op.id(), OperandMode.DEF)) {
175                    /*
176                     * This happens if a materializable interval is originally not spilled but then
177                     * kicked out in LinearScanWalker.splitForSpilling(). When kicking out such an
178                     * interval this move operation was already generated.
179                     */
180                    instructions.set(j, null);
181                    hasDead = true;
182                    continue;
183                }
184            }
185
186            op.forEachInput(assignProc);
187            op.forEachAlive(assignProc);
188            op.forEachTemp(assignProc);
189            op.forEachOutput(assignProc);
190
191            // compute reference map and debug information
192            op.forEachState((inst, state) -> computeDebugInfo(inst, state));
193
194            // remove useless moves
195            if (move != null) {
196                if (move.getInput().equals(move.getResult())) {
197                    instructions.set(j, null);
198                    hasDead = true;
199                }
200            }
201        }
202
203        if (hasDead) {
204            // Remove null values from the list.
205            instructions.removeAll(Collections.singleton(null));
206        }
207    }
208
209    private void assignLocations() {
210        try (Indent indent = Debug.logAndIndent("assign locations")) {
211            for (AbstractBlockBase<?> block : allocator.sortedBlocks()) {
212                try (Indent indent2 = Debug.logAndIndent("assign locations in block B%d", block.getId())) {
213                    assignLocations(allocator.getLIR().getLIRforBlock(block));
214                }
215            }
216        }
217    }
218}