/** Instrument the specified method to replace mapped calls. */
public void instrument_method(Method m, MethodGen mg) {
// Loop through each instruction, making substitutions
InstructionList il = mg.getInstructionList();
for (InstructionHandle ih = il.getStart(); ih != null; ) {
if (debug_instrument_inst.enabled()) {
debug_instrument_inst.log("instrumenting instruction %s%n", ih);
// ih.getInstruction().toString(pool.getConstantPool()));
}
InstructionList new_il = null;
// Remember the next instruction to process
InstructionHandle next_ih = ih.getNext();
// Get the translation for this instruction (if any)
new_il = xform_inst(mg, ih.getInstruction());
if (debug_instrument_inst.enabled()) debug_instrument_inst.log(" new inst: %s%n", new_il);
// If this instruction was modified, replace it with the new
// instruction list. If this instruction was the target of any
// jumps or line numbers , replace them with the first
// instruction in the new list
replace_instructions(il, ih, new_il);
ih = next_ih;
}
}
/**
* Replace instruction ih in list il with the instructions in new_il. If new_il is null, do
* nothing
*/
protected static void replace_instructions(
InstructionList il, InstructionHandle ih, InstructionList new_il) {
if ((new_il == null) || new_il.isEmpty()) return;
// If there is only one new instruction, just replace it in the handle
if (new_il.getLength() == 1) {
ih.setInstruction(new_il.getEnd().getInstruction());
return;
}
// Get the start and end instruction of the new instructions
InstructionHandle new_end = new_il.getEnd();
InstructionHandle new_start = il.insert(ih, new_il);
// Move all of the branches from the old instruction to the new start
il.redirectBranches(ih, new_start);
// Move other targets to the new instuctions.
if (ih.hasTargeters()) {
for (InstructionTargeter it : ih.getTargeters()) {
if (it instanceof LineNumberGen) {
it.updateTarget(ih, new_start);
} else if (it instanceof LocalVariableGen) {
it.updateTarget(ih, new_end);
} else if (it instanceof CodeExceptionGen) {
CodeExceptionGen exc = (CodeExceptionGen) it;
if (exc.getStartPC() == ih) exc.updateTarget(ih, new_start);
else if (exc.getEndPC() == ih) exc.updateTarget(ih, new_end);
else if (exc.getHandlerPC() == ih) exc.setHandlerPC(new_start);
else System.out.printf("Malformed CodeException: %s%n", exc);
} else {
System.out.printf("unexpected target %s%n", it);
}
}
}
// Remove the old handle. There should be no targeters left to it.
try {
il.delete(ih);
} catch (Exception e) {
throw new Error("Can't delete instruction", e);
}
}
/**
* Long output format:
*
* <p><position in byte code> <name of opcode> "["<opcode number>"]"
* "("<length of instruction>")" "<"<target instruction>">" "@"<branch target
* offset>
*
* @param verbose long/short format switch
* @return mnemonic for instruction
*/
public String toString(boolean verbose) {
String s = super.toString(verbose);
String t = "null";
if (verbose) {
if (target != null) {
if (target.getInstruction() == this) t = "<points to itself>";
else if (target.getInstruction() == null) t = "<null instruction!!!?>";
else t = target.getInstruction().toString(false); // Avoid circles
}
} else {
if (target != null) {
index = getTargetOffset();
t = "" + (index + position);
}
}
return s + " -> " + t;
}
/**
* @param target branch target
* @return the offset to `target' relative to this instruction
*/
protected int getTargetOffset(InstructionHandle target) {
if (target == null)
throw new ClassGenException("Target of " + super.toString(true) + " is invalid null handle");
int t = target.getPosition();
if (t < 0)
throw new ClassGenException(
"Invalid branch target position offset for "
+ super.toString(true)
+ ":"
+ t
+ ":"
+ target);
return t - position;
}
/** Used by BranchInstruction, LocalVariableGen, CodeExceptionGen */
static final void notifyTarget(
InstructionHandle old_ih, InstructionHandle new_ih, InstructionTargeter t) {
if (old_ih != null) old_ih.removeTargeter(t);
if (new_ih != null) new_ih.addTargeter(t);
}
