private void deallocateNonLiveVars(Line line, RegAllocContext context, int nMaxRegisters) {
// De-allocate non-live variables
for (int i = 0; i < nMaxRegisters - 1; i++) {
String strReg = "$t" + i;
// See if it is live in the next instruction.
// Get the variable the register is mapped to
String strVar = context.regMap.get(strReg);
// If it is not live...
if (null != strVar && !line.getLiveSet().contains(strVar)) {
// Remove mapping from old variable to register
context.regMap.put(strReg, "");
context.variableLocs.put(strVar, "m");
}
}
}
public boolean calculateLiveIN() {
boolean bChanges = false;
mapRegistersToVariables();
// The last lastLive set is a copy of liveOUT
LiveSet lastLive = new LiveSet(getLiveOut());
for (int i = getLines().getNumItems() - 1; i >= 0; i--) {
Line line = getLines().getItemAtIndex(i);
// Copy the last live set
line.getLiveSet().copy(lastLive);
if (Line.Type.INSTRUCTION == line.getType()) {
Instruction instr = (Instruction) line;
Argument arg2 = instr.getArgument2();
// If this is a SW instruction, then remove the
// target variable from the live set
if (0 == instr.getInstruction().compareTo("sw")) {
// Remove the mapping to the variable
line.getLiveSet().remove(arg2.getName());
// See if Argument1 is mapped to a variable
if (instr.getMapRegToValue().containsKey(instr.getArgument1().getName())) {
String strVal = instr.getMapRegToValue().get(instr.getArgument1().getName());
// Mark the variable as live
line.getLiveSet().add(strVal);
}
}
// If this is a LW instruction, then add the loaded
// variable to the live set
else if (0 == instr.getInstruction().compareTo("lw")
|| 0 == instr.getInstruction().compareTo("li")) {
line.getLiveSet().add(arg2.getName());
} else if (!instr.getIsJump()
&& 0 != instr.getInstruction().compareTo("syscall")
&& 0 != instr.getInstruction().compareTo("move")
&& 0 != instr.getInstruction().compareTo("li")) {
// See if Argument2 is mapped to a variable
if (instr.getMapRegToValue().containsKey(instr.getArgument2().getName())) {
String strVal = instr.getMapRegToValue().get(instr.getArgument2().getName());
// Mark the variable as live
line.getLiveSet().add(strVal);
}
// See if Argument3 is mapped to a variable
if (instr.getMapRegToValue().containsKey(instr.getArgument3().getName())) {
String strVal = instr.getMapRegToValue().get(instr.getArgument3().getName());
// Mark the variable as live
line.getLiveSet().add(strVal);
}
} else if (0 == instr.getInstruction().compareTo("move")) {
// See if Argument2 is mapped to a variable
if (instr.getMapRegToValue().containsKey(instr.getArgument2().getName())) {
String strVal = instr.getMapRegToValue().get(instr.getArgument2().getName());
// Mark the variable as live
line.getLiveSet().add(strVal);
}
}
}
lastLive = line.getLiveSet();
}
getLiveIn().copy(lastLive);
return bChanges;
}