/**
* Is register r1 live at any def of register r2?
*
* <p><strong>PRECONDITION </strong> def-use chains must be computed and valid.
* <strong>PRECONDITION </strong> instructions are numbered, with numbers stored in
* OPT_Instruction.scratch
*
* <p>Note: this implementation is not efficient. The liveness data structures must be re-designed
* to support this efficiently.
*/
private static boolean isLiveAtDef(OPT_Register r1, OPT_Register r2, OPT_LiveAnalysis live) {
for (Iterator e = live.iterateLiveIntervals(r1); e.hasNext(); ) {
OPT_LiveIntervalElement elem = (OPT_LiveIntervalElement) e.next();
OPT_BasicBlock bb = elem.getBasicBlock();
OPT_Instruction begin = (elem.getBegin() == null) ? bb.firstInstruction() : elem.getBegin();
OPT_Instruction end = (elem.getEnd() == null) ? bb.lastInstruction() : elem.getEnd();
int low = begin.scratch;
int high = end.scratch;
for (Enumeration defs = OPT_DefUse.defs(r2); defs.hasMoreElements(); ) {
OPT_Operand def = (OPT_Operand) defs.nextElement();
int n = def.instruction.scratch;
if (n >= low && n < high) {
return true;
}
}
}
// no conflict was found.
return false;
}
