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package org.graalvm.compiler.lir;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.graalvm.compiler.core.common.cfg.AbstractBlockBase;
import org.graalvm.compiler.core.common.cfg.AbstractControlFlowGraph;
import org.graalvm.compiler.core.common.cfg.BlockMap;
import org.graalvm.compiler.lir.StandardOp.BlockEndOp;
import org.graalvm.compiler.lir.StandardOp.LabelOp;
import org.graalvm.compiler.lir.gen.LIRGenerator;

This class implements the overall container for the LIR graph and directs its construction, optimization, and finalization.
/** * This class implements the overall container for the LIR graph and directs its construction, * optimization, and finalization. */
public final class LIR extends LIRGenerator.VariableProvider { private final AbstractControlFlowGraph<?> cfg;
The linear-scan ordered list of blocks.
/** * The linear-scan ordered list of blocks. */
private final AbstractBlockBase<?>[] linearScanOrder;
The order in which the code is emitted.
/** * The order in which the code is emitted. */
private final AbstractBlockBase<?>[] codeEmittingOrder;
Map from block to LIRInstructions. Note that we are using ArrayList instead of List to avoid interface dispatch.
/** * Map from {@linkplain AbstractBlockBase block} to {@linkplain LIRInstruction}s. Note that we * are using {@link ArrayList} instead of {@link List} to avoid interface dispatch. */
private final BlockMap<ArrayList<LIRInstruction>> lirInstructions; private boolean hasArgInCallerFrame;
Creates a new LIR instance for the specified compilation.
/** * Creates a new LIR instance for the specified compilation. */
public LIR(AbstractControlFlowGraph<?> cfg, AbstractBlockBase<?>[] linearScanOrder, AbstractBlockBase<?>[] codeEmittingOrder) { this.cfg = cfg; this.codeEmittingOrder = codeEmittingOrder; this.linearScanOrder = linearScanOrder; this.lirInstructions = new BlockMap<>(cfg); } public AbstractControlFlowGraph<?> getControlFlowGraph() { return cfg; }
Determines if any instruction in the LIR has debug info associated with it.
/** * Determines if any instruction in the LIR has debug info associated with it. */
public boolean hasDebugInfo() { for (AbstractBlockBase<?> b : linearScanOrder()) { for (LIRInstruction op : getLIRforBlock(b)) { if (op.hasState()) { return true; } } } return false; } public ArrayList<LIRInstruction> getLIRforBlock(AbstractBlockBase<?> block) { return lirInstructions.get(block); } public void setLIRforBlock(AbstractBlockBase<?> block, ArrayList<LIRInstruction> list) { assert getLIRforBlock(block) == null : "lir instruction list should only be initialized once"; lirInstructions.put(block, list); }
Gets the linear scan ordering of blocks as an array.
Returns:the blocks in linear scan order
/** * Gets the linear scan ordering of blocks as an array. * * @return the blocks in linear scan order */
public AbstractBlockBase<?>[] linearScanOrder() { return linearScanOrder; } public AbstractBlockBase<?>[] codeEmittingOrder() { return codeEmittingOrder; } public void setHasArgInCallerFrame() { hasArgInCallerFrame = true; }
Determines if any of the parameters to the method are passed via the stack where the parameters are located in the caller's frame.
/** * Determines if any of the parameters to the method are passed via the stack where the * parameters are located in the caller's frame. */
public boolean hasArgInCallerFrame() { return hasArgInCallerFrame; }
Gets the next non-null block in a list.
Params:
  • blocks – list of blocks
  • blockIndex – index of the current block
Returns:the next block in the list that is none null or null if there is no such block
/** * Gets the next non-{@code null} block in a list. * * @param blocks list of blocks * @param blockIndex index of the current block * @return the next block in the list that is none {@code null} or {@code null} if there is no * such block */
public static AbstractBlockBase<?> getNextBlock(AbstractBlockBase<?>[] blocks, int blockIndex) { for (int nextIndex = blockIndex + 1; nextIndex > 0 && nextIndex < blocks.length; nextIndex++) { AbstractBlockBase<?> nextBlock = blocks[nextIndex]; if (nextBlock != null) { return nextBlock; } } return null; }
Gets the exception edge (if any) originating at a given operation.
/** * Gets the exception edge (if any) originating at a given operation. */
public static LabelRef getExceptionEdge(LIRInstruction op) { final LabelRef[] exceptionEdge = {null}; op.forEachState(state -> { if (state.exceptionEdge != null) { assert exceptionEdge[0] == null; exceptionEdge[0] = state.exceptionEdge; } }); return exceptionEdge[0]; }
The maximum distance an operation with an exception edge can be from the last instruction of a LIR block. The value of 3 is based on a non-void call operation that has an exception edge. Such a call may move the result to another register and then spill it.

The rationale for such a constant is to limit the search for an insertion point when adding move operations at the end of a block. Such moves must be inserted before all control flow instructions.

/** * The maximum distance an operation with an {@linkplain #getExceptionEdge(LIRInstruction) * exception edge} can be from the last instruction of a LIR block. The value of 3 is based on a * non-void call operation that has an exception edge. Such a call may move the result to * another register and then spill it. * <p> * The rationale for such a constant is to limit the search for an insertion point when adding * move operations at the end of a block. Such moves must be inserted before all control flow * instructions. */
public static final int MAX_EXCEPTION_EDGE_OP_DISTANCE_FROM_END = 3; public static boolean verifyBlock(LIR lir, AbstractBlockBase<?> block) { ArrayList<LIRInstruction> ops = lir.getLIRforBlock(block); if (ops.size() == 0) { return false; } assert ops.get(0) instanceof LabelOp : String.format("Not a Label %s (Block %s)", ops.get(0).getClass(), block); LIRInstruction opWithExceptionEdge = null; int index = 0; int lastIndex = ops.size() - 1; for (LIRInstruction op : ops.subList(0, lastIndex)) { assert !(op instanceof BlockEndOp) : String.format("BlockEndOp %s (Block %s)", op.getClass(), block); LabelRef exceptionEdge = getExceptionEdge(op); if (exceptionEdge != null) { assert opWithExceptionEdge == null : "multiple ops with an exception edge not allowed"; opWithExceptionEdge = op; int distanceFromEnd = lastIndex - index; assert distanceFromEnd <= MAX_EXCEPTION_EDGE_OP_DISTANCE_FROM_END; } index++; } LIRInstruction end = ops.get(lastIndex); assert end instanceof BlockEndOp : String.format("Not a BlockEndOp %s (Block %s)", end.getClass(), block); return true; } public static boolean verifyBlocks(LIR lir, AbstractBlockBase<?>[] blocks) { for (AbstractBlockBase<?> block : blocks) { if (block == null) { continue; } for (AbstractBlockBase<?> sux : block.getSuccessors()) { assert Arrays.asList(blocks).contains(sux) : "missing successor from: " + block + "to: " + sux; } for (AbstractBlockBase<?> pred : block.getPredecessors()) { assert Arrays.asList(blocks).contains(pred) : "missing predecessor from: " + block + "to: " + pred; } if (!verifyBlock(lir, block)) { return false; } } return true; } public void resetLabels() { for (AbstractBlockBase<?> block : codeEmittingOrder()) { if (block == null) { continue; } for (LIRInstruction inst : lirInstructions.get(block)) { if (inst instanceof LabelOp) { ((LabelOp) inst).getLabel().reset(); } } } } }