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package org.graalvm.compiler.asm;

import java.util.ArrayList;

This class represents a label within assembly code.
/** * This class represents a label within assembly code. */
public final class Label { private int position = -1; private int blockId = -1;
References to instructions that jump to this unresolved label. These instructions need to be patched when the label is bound using the patchInstructions(Assembler) method.
/** * References to instructions that jump to this unresolved label. These instructions need to be * patched when the label is bound using the {@link #patchInstructions(Assembler)} method. */
private ArrayList<Integer> patchPositions = null;
Returns the position of this label in the code buffer.
Returns:the position
/** * Returns the position of this label in the code buffer. * * @return the position */
public int position() { assert position >= 0 : "Unbound label is being referenced"; return position; } public Label() { } public Label(int id) { blockId = id; } public int getBlockId() { return blockId; }
Binds the label to the specified position.
Params:
  • pos – the position
/** * Binds the label to the specified position. * * @param pos the position */
protected void bind(int pos) { this.position = pos; assert isBound(); } public boolean isBound() { return position >= 0; } public void addPatchAt(int branchLocation) { assert !isBound() : "Label is already bound " + this + " " + branchLocation + " at position " + position; if (patchPositions == null) { patchPositions = new ArrayList<>(2); } patchPositions.add(branchLocation); } protected void patchInstructions(Assembler masm) { assert isBound() : "Label should be bound"; if (patchPositions != null) { int target = position; for (int i = 0; i < patchPositions.size(); ++i) { int pos = patchPositions.get(i); masm.patchJumpTarget(pos, target); } } } public void reset() { if (this.patchPositions != null) { this.patchPositions.clear(); } this.position = -1; } @Override public String toString() { return isBound() ? String.valueOf(position()) : "?"; } }