1 /* 2 * Copyright (c) 2015, 2017, 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.lsra; 24 25 import static jdk.vm.ci.code.ValueUtil.isRegister; 26 import static org.graalvm.compiler.core.common.GraalOptions.DetailedAsserts; 27 import static org.graalvm.compiler.lir.LIRValueUtil.asVariable; 28 import static org.graalvm.compiler.lir.LIRValueUtil.isStackSlotValue; 29 import static org.graalvm.compiler.lir.LIRValueUtil.isVariable; 30 31 import java.util.ArrayList; 32 33 import org.graalvm.compiler.core.common.alloc.RegisterAllocationConfig; 34 import org.graalvm.compiler.core.common.alloc.Trace; 35 import org.graalvm.compiler.core.common.alloc.TraceBuilderResult; 36 import org.graalvm.compiler.core.common.cfg.AbstractBlockBase; 37 import org.graalvm.compiler.debug.Debug; 38 import org.graalvm.compiler.debug.Indent; 39 import org.graalvm.compiler.lir.LIRInsertionBuffer; 40 import org.graalvm.compiler.lir.LIRInstruction; 41 import org.graalvm.compiler.lir.LIRInstruction.OperandMode; 42 import org.graalvm.compiler.lir.StandardOp.LoadConstantOp; 43 import org.graalvm.compiler.lir.StandardOp.MoveOp; 44 import org.graalvm.compiler.lir.StandardOp.ValueMoveOp; 45 import org.graalvm.compiler.lir.alloc.trace.lsra.TraceInterval.SpillState; 46 import org.graalvm.compiler.lir.alloc.trace.lsra.TraceLinearScanPhase.IntervalPredicate; 47 import org.graalvm.compiler.lir.alloc.trace.lsra.TraceLinearScanPhase.TraceLinearScan; 48 import org.graalvm.compiler.lir.gen.LIRGenerationResult; 49 import org.graalvm.compiler.lir.gen.LIRGeneratorTool.MoveFactory; 50 51 import jdk.vm.ci.code.TargetDescription; 52 import jdk.vm.ci.meta.AllocatableValue; 53 54 final class TraceLinearScanEliminateSpillMovePhase extends TraceLinearScanAllocationPhase { 55 56 private static final IntervalPredicate spilledIntervals = new TraceLinearScanPhase.IntervalPredicate() { 57 58 @Override 59 public boolean apply(TraceInterval i) { 60 return i.isSplitParent() && SpillState.IN_MEMORY.contains(i.spillState()); 61 } 62 }; 63 64 @Override 65 protected void run(TargetDescription target, LIRGenerationResult lirGenRes, Trace trace, MoveFactory spillMoveFactory, RegisterAllocationConfig registerAllocationConfig, 66 TraceBuilderResult traceBuilderResult, TraceLinearScan allocator) { 67 boolean shouldEliminateSpillMoves = shouldEliminateSpillMoves(traceBuilderResult, allocator); 68 eliminateSpillMoves(allocator, shouldEliminateSpillMoves, traceBuilderResult, lirGenRes); 69 } 70 71 private static boolean shouldEliminateSpillMoves(TraceBuilderResult traceBuilderResult, TraceLinearScan allocator) { 72 return !traceBuilderResult.incomingSideEdges(traceBuilderResult.getTraceForBlock(allocator.blockAt(0))); 73 } 74 75 // called once before assignment of register numbers 76 @SuppressWarnings("try") 77 private static void eliminateSpillMoves(TraceLinearScan allocator, boolean shouldEliminateSpillMoves, TraceBuilderResult traceBuilderResult, LIRGenerationResult res) { 78 try (Indent indent = Debug.logAndIndent("Eliminating unnecessary spill moves: Trace%d", traceBuilderResult.getTraceForBlock(allocator.blockAt(0)).getId())) { 79 allocator.sortIntervalsBySpillPos(); 80 81 /* 82 * collect all intervals that must be stored after their definition. The list is sorted 83 * by Interval.spillDefinitionPos. 84 */ 85 TraceInterval interval = allocator.createUnhandledListBySpillPos(spilledIntervals); 86 if (DetailedAsserts.getValue(allocator.getOptions())) { 87 checkIntervals(interval); 88 } 89 if (Debug.isLogEnabled()) { 90 try (Indent indent2 = Debug.logAndIndent("Sorted intervals")) { 91 for (TraceInterval i = interval; i != null; i = i.next) { 92 Debug.log("%5d: %s", i.spillDefinitionPos(), i); 93 } 94 } 95 } 96 97 LIRInsertionBuffer insertionBuffer = new LIRInsertionBuffer(); 98 for (AbstractBlockBase<?> block : allocator.sortedBlocks()) { 99 try (Indent indent1 = Debug.logAndIndent("Handle %s", block)) { 100 ArrayList<LIRInstruction> instructions = allocator.getLIR().getLIRforBlock(block); 101 int numInst = instructions.size(); 102 103 int lastOpId = -1; 104 // iterate all instructions of the block. 105 for (int j = 0; j < numInst; j++) { 106 LIRInstruction op = instructions.get(j); 107 int opId = op.id(); 108 try (Indent indent2 = Debug.logAndIndent("%5d %s", opId, op)) { 109 110 if (opId == -1) { 111 MoveOp move = MoveOp.asMoveOp(op); 112 /* 113 * Remove move from register to stack if the stack slot is 114 * guaranteed to be correct. Only moves that have been inserted by 115 * LinearScan can be removed. 116 */ 117 if (shouldEliminateSpillMoves && canEliminateSpillMove(allocator, block, move, lastOpId)) { 118 /* 119 * Move target is a stack slot that is always correct, so 120 * eliminate instruction. 121 */ 122 if (Debug.isLogEnabled()) { 123 if (ValueMoveOp.isValueMoveOp(op)) { 124 ValueMoveOp vmove = ValueMoveOp.asValueMoveOp(op); 125 Debug.log("eliminating move from interval %s to %s in block %s", vmove.getInput(), vmove.getResult(), block); 126 } else { 127 LoadConstantOp load = LoadConstantOp.asLoadConstantOp(op); 128 Debug.log("eliminating constant load from %s to %s in block %s", load.getConstant(), load.getResult(), 129 block); 130 } 131 } 132 133 // null-instructions are deleted by assignRegNum 134 instructions.set(j, null); 135 } 136 137 } else { 138 lastOpId = opId; 139 /* 140 * Insert move from register to stack just after the beginning of 141 * the interval. 142 */ 143 // assert interval == TraceInterval.EndMarker || 144 // interval.spillDefinitionPos() >= opId : "invalid order"; 145 assert interval == TraceInterval.EndMarker || (interval.isSplitParent() && SpillState.IN_MEMORY.contains(interval.spillState())) : "invalid interval"; 146 147 while (interval != TraceInterval.EndMarker && interval.spillDefinitionPos() == opId) { 148 Debug.log("handle %s", interval); 149 if (!interval.canMaterialize() && interval.spillState() != SpillState.StartInMemory) { 150 151 AllocatableValue fromLocation = interval.getSplitChildAtOpId(opId, OperandMode.DEF).location(); 152 AllocatableValue toLocation = allocator.canonicalSpillOpr(interval); 153 if (!fromLocation.equals(toLocation)) { 154 155 if (!insertionBuffer.initialized()) { 156 /* 157 * prepare insertion buffer (appended when all 158 * instructions in the block are processed) 159 */ 160 insertionBuffer.init(instructions); 161 } 162 163 assert isRegister(fromLocation) : "from operand must be a register but is: " + fromLocation + " toLocation=" + toLocation + " spillState=" + 164 interval.spillState(); 165 assert isStackSlotValue(toLocation) : "to operand must be a stack slot"; 166 167 LIRInstruction move = allocator.getSpillMoveFactory().createMove(toLocation, fromLocation); 168 insertionBuffer.append(j + 1, move); 169 move.setComment(res, "TraceLSRAEliminateSpillMove: spill def pos"); 170 171 if (Debug.isLogEnabled()) { 172 Debug.log("inserting move after definition of interval %d to stack slot %s at opId %d", interval.operandNumber, interval.spillSlot(), opId); 173 } 174 } 175 } 176 interval = interval.next; 177 } 178 } 179 } 180 } // end of instruction iteration 181 182 if (insertionBuffer.initialized()) { 183 insertionBuffer.finish(); 184 } 185 } 186 } // end of block iteration 187 188 assert interval == TraceInterval.EndMarker : "missed an interval"; 189 } 190 } 191 192 /** 193 * @param allocator 194 * @param block The block {@code move} is located in. 195 * @param move Spill move. 196 * @param lastOpId The id of last "normal" instruction before the spill move. (Spill moves have 197 * no valid opId but -1.) 198 */ 199 private static boolean canEliminateSpillMove(TraceLinearScan allocator, AbstractBlockBase<?> block, MoveOp move, int lastOpId) { 200 assert ((LIRInstruction) move).id() == -1 : "Not a spill move: " + move; 201 assert isVariable(move.getResult()) : "LinearScan inserts only moves to variables: " + move; 202 assert lastOpId >= 0 : "Invalid lastOpId: " + lastOpId; 203 204 TraceInterval curInterval = allocator.intervalFor(asVariable(move.getResult())); 205 206 if (!isRegister(curInterval.location()) && curInterval.inMemoryAt(lastOpId) && !isPhiResolutionMove(allocator, move)) { 207 /* Phi resolution moves cannot be removed because they define the value. */ 208 // TODO (je) check if the comment is still valid! 209 assert isStackSlotValue(curInterval.location()) : "Not a stack slot: " + curInterval.location(); 210 return true; 211 } 212 return false; 213 } 214 215 /** 216 * Checks if a (spill or split) move is a Phi resolution move. 217 * 218 * A spill or split move connects a split parent or a split child with another split child. 219 * Therefore the destination of the move is always a split child. Phi resolution moves look like 220 * spill moves (i.e. {@link LIRInstruction#id() id} is {@code 0}, but they define a new 221 * variable. As a result the destination interval is a split parent. 222 */ 223 private static boolean isPhiResolutionMove(TraceLinearScan allocator, MoveOp move) { 224 assert ((LIRInstruction) move).id() == -1 : "Not a spill move: " + move; 225 TraceInterval curInterval = allocator.intervalFor(asVariable(move.getResult())); 226 return curInterval.isSplitParent(); 227 } 228 229 private static void checkIntervals(TraceInterval interval) { 230 TraceInterval prev = null; 231 TraceInterval temp = interval; 232 while (temp != TraceInterval.EndMarker) { 233 assert temp.spillDefinitionPos() >= 0 : "invalid spill definition pos " + temp; 234 if (prev != null) { 235 // assert temp.from() >= prev.from() : "intervals not sorted"; 236 assert temp.spillDefinitionPos() >= prev.spillDefinitionPos() : "when intervals are sorted by from : then they must also be sorted by spillDefinitionPos"; 237 } 238 239 assert temp.spillSlot() != null || temp.canMaterialize() : "interval has no spill slot assigned"; 240 assert temp.spillDefinitionPos() >= temp.from() : "invalid order"; 241 // assert temp.spillDefinitionPos() <= temp.from() + 2 : 242 // "only intervals defined once at their start-pos can be optimized"; 243 244 if (Debug.isLogEnabled()) { 245 Debug.log("interval %d (from %d to %d) must be stored at %d", temp.operandNumber, temp.from(), temp.to(), temp.spillDefinitionPos()); 246 } 247 248 prev = temp; 249 temp = temp.next; 250 } 251 } 252 253 }