org.aspectj/weaver/src/main/java/org/aspectj/weaver/bcel/ShadowRange.java

/* *******************************************************************
 * Copyright (c) 2002 Palo Alto Research Center, Incorporated (PARC).
 * All rights reserved. 
 * This program and the accompanying materials are made available 
 * under the terms of the Eclipse Public License v1.0 
 * which accompanies this distribution and is available at 
 * http://www.eclipse.org/legal/epl-v10.html 
 *  
 * Contributors: 
 *     PARC     initial implementation 
 * ******************************************************************/

package org.aspectj.weaver.bcel;

import java.util.Iterator;

import org.aspectj.apache.bcel.generic.Instruction;
import org.aspectj.apache.bcel.generic.InstructionBranch;
import org.aspectj.apache.bcel.generic.InstructionFactory;
import org.aspectj.apache.bcel.generic.InstructionHandle;
import org.aspectj.apache.bcel.generic.InstructionLV;
import org.aspectj.apache.bcel.generic.InstructionList;
import org.aspectj.apache.bcel.generic.InstructionSelect;
import org.aspectj.apache.bcel.generic.InstructionTargeter;
import org.aspectj.apache.bcel.generic.LocalVariableTag;
import org.aspectj.apache.bcel.generic.RET;
import org.aspectj.apache.bcel.generic.TargetLostException;
import org.aspectj.weaver.BCException;
import org.aspectj.weaver.IntMap;
import org.aspectj.weaver.Shadow;

final class ShadowRange extends Range {

	private BcelShadow shadow;

	// ---- initialization

	/**
	 * After this constructor is called, this range is not well situated unless both {@link #associateWithTargets} and
	 * {@link #associateWithShadow} are called.
	 */
	public ShadowRange(InstructionList body) {
		super(body);
	}

	protected void associateWithTargets(InstructionHandle start, InstructionHandle end) {
		// assert body.contains(start) && body.contains(end);
		this.start = start;
		this.end = end;
		start.addTargeter(this);
		end.addTargeter(this);
	}

	public void associateWithShadow(BcelShadow shadow) {
		this.shadow = shadow;
		shadow.setRange(this);
	}

	// ----

	public Shadow.Kind getKind() {
		return shadow.getKind();
	}

	@Override
	public String toString() {
		return shadow.toString();
	}

	void extractInstructionsInto(LazyMethodGen freshMethod, IntMap remap, boolean addReturn) {
		LazyMethodGen.assertGoodBody(getBody(), toString());
		freshMethod.assertGoodBody();
		InstructionList freshBody = freshMethod.getBody();

		for (InstructionHandle oldIh = start.getNext(); oldIh != end; oldIh = oldIh.getNext()) {
			// first we copy the instruction itself.
			Instruction oldI = oldIh.getInstruction();
			Instruction freshI = (oldI == RANGEINSTRUCTION) ? oldI : Utility.copyInstruction(oldI);

			// Now we add it to the new instruction list.
			InstructionHandle freshIh;
			if (freshI instanceof InstructionBranch) {
				// If it's a targeting instruction,
				// update the target(s) to point to the new copy instead of the old copy.
				InstructionBranch oldBranch = (InstructionBranch) oldI;
				InstructionBranch freshBranch = (InstructionBranch) freshI;
				InstructionHandle oldTarget = oldBranch.getTarget();
				oldTarget.removeTargeter(oldBranch);
				oldTarget.addTargeter(freshBranch);
				if (freshBranch instanceof InstructionSelect) {
					InstructionSelect oldSelect = (InstructionSelect) oldI;
					InstructionSelect freshSelect = (InstructionSelect) freshI;
					InstructionHandle[] oldTargets = freshSelect.getTargets();
					for (int k = oldTargets.length - 1; k >= 0; k--) {
						oldTargets[k].removeTargeter(oldSelect);
						oldTargets[k].addTargeter(freshSelect);
					}
				}
				freshIh = freshBody.append(freshBranch);
			} else {
				freshIh = freshBody.append(freshI);
			}

			// if source comes before target:
			// source <--> target
			// --> [process: target.removeTargeter(source); target.addTargeter(sourcecopy)]
			// source ---------\
			// v
			// sourcecopy <--> target
			// --> [ process: sourcecopy.updateTarget(target, targetcopy) ]
			// source ----> target
			// sourcecopy <--> targetcopy

			// if target comes before source

			// target <--> source
			// --> [process: source.updateTarget(target, targetcopy) ]
			// target
			// targetcopy <--> source
			// --> [process: targetcopy.removeTargeter(source); targetcopy.addTargeter(sourcecopy)]
			// target source
			// v
			// targetcopy <--> sourcecopy

			// now deal with the old instruction's targeters. Update them all to point to us
			// instead of the old instruction. We use updateTarget to do this. One goal is
			// to make sure we remove all targeters from the old guy, so we can successfully
			// delete it.
			for (InstructionTargeter source : oldIh.getTargetersCopy()) {
				if (source instanceof LocalVariableTag) {
					Shadow.Kind kind = getKind();
					if (kind == Shadow.AdviceExecution || kind == Shadow.ConstructorExecution || kind == Shadow.MethodExecution
							|| kind == Shadow.PreInitialization || kind == Shadow.Initialization
							|| kind == Shadow.StaticInitialization) {
						LocalVariableTag sourceLocalVariableTag = (LocalVariableTag) source;
						if (sourceLocalVariableTag.getSlot() == 0) {
							// might be 'this' so should be renamed if being dumped in a static method 277616
							if (sourceLocalVariableTag.getName().equals("this")) {
								sourceLocalVariableTag.setName("ajc$this");
							}
						}
						// if we're extracting a whole block we can do this...
						source.updateTarget(oldIh, freshIh);
					} else {
						// XXX destroying local variable info
						// but only for a call or get join point, so no big deal
						source.updateTarget(oldIh, null);
					}
				} else if (source instanceof Range) {
					// exceptions and shadows are just moved
					((Range) source).updateTarget(oldIh, freshIh, freshBody);
				} else {
					// line numbers can be shared,
					// branches will be copied along with us.
					source.updateTarget(oldIh, freshIh);
				}
			}
			// we're now done with the old instruction entirely, and will ignore them through
			// the rest of this loop. The only time we'll see them again is a second pass to
			// delete them.

			// now deal with local variable instructions. If this points to a remapped
			// frame location, update the instruction's index. If this doesn't,
			// do compaction/expansion: allocate a new local variable, and modify the remap
			// to handle it. XXX We're doing the safe thing and allocating ALL these local variables
			// as double-wides, in case the location is found to hold a double-wide later.
			if (freshI.isLocalVariableInstruction() || freshI instanceof RET) {
				// IndexedInstruction indexedI = (IndexedInstruction) freshI;
				int oldIndex = freshI.getIndex();
				int freshIndex;
				if (!remap.hasKey(oldIndex)) {
					freshIndex = freshMethod.allocateLocal(2);
					remap.put(oldIndex, freshIndex);
				} else {
					freshIndex = remap.get(oldIndex);
				}
				if (freshI instanceof RET) {
					freshI.setIndex(freshIndex);
				} else {
					freshI = ((InstructionLV) freshI).setIndexAndCopyIfNecessary(freshIndex);
					freshIh.setInstruction(freshI);
				}
			}
			// System.err.println("JUST COPIED: " +
			// oldIh.getInstruction().toString(freshMethod.getEnclosingClass().getConstantPoolGen().getConstantPool())
			// + " INTO " +
			// freshIh.getInstruction().toString(freshMethod.getEnclosingClass().getConstantPoolGen().getConstantPool()));
		}

		// now go through again and update variable slots that have been altered as a result
		// of remapping...
		for (InstructionHandle newIh = freshBody.getStart(); newIh != freshBody.getEnd(); newIh = newIh.getNext()) {
			for (InstructionTargeter source : newIh.getTargeters()) {
				if (source instanceof LocalVariableTag) {
					LocalVariableTag lvt = (LocalVariableTag) source;
					if (!lvt.isRemapped() && remap.hasKey(lvt.getSlot())) {
						lvt.updateSlot(remap.get(lvt.getSlot()));
					}
				}
			}
		}

		// we've now copied out all the instructions.
		// now delete the instructions... we've already taken care of the damn
		// targets, but since TargetLostException is checked, we have to do this stuff.
		try {
			for (InstructionHandle oldIh = start.getNext(); oldIh != end;) {
				InstructionHandle next = oldIh.getNext();
				body.delete(oldIh);
				oldIh = next;
			}
		} catch (TargetLostException e) {
			throw new BCException("shouldn't have gotten a target lost");
		}

		// now add the return, if one is warranted.
		InstructionHandle ret = null;
		if (addReturn) {
			// we really should pull this out somewhere...
			ret = freshBody.append(InstructionFactory.createReturn(freshMethod.getReturnType()));
		}
		// and remap all the old targeters of the end handle of the range to the return.
		for (InstructionTargeter t : end.getTargetersCopy()) {
			if (t == this) {
				continue;
			}
			if (!addReturn) {
				throw new BCException("range has target, but we aren't adding a return");
			} else {
				t.updateTarget(end, ret);
			}
		}

		LazyMethodGen.assertGoodBody(getBody(), toString());
		freshMethod.assertGoodBody();
	}

	public BcelShadow getShadow() {
		return shadow;
	}

}