/**
* Attempt to rewrite a move instruction to a NOP.
*
* @param s the instruction to rewrite
* @return {@code true} if and only if the transformation applies
*/
private boolean mutateMoveToNop(Instruction s) {
Operand result = MIR_Move.getResult(s);
Operand val = MIR_Move.getValue(s);
if (result.isStackLocation() && val.isStackLocation()) {
if (result.similar(val)) {
Empty.mutate(s, NOP);
return true;
}
}
return false;
}
/**
* Mutate FMOVs that end live ranges
*
* @param live The live interval for a basic block/reg pair
* @param register The register for this live interval
* @param dfnbegin The (adjusted) begin for this interval
* @param dfnend The (adjusted) end for this interval
*/
@Override
public boolean mutateFMOVs(
OPT_LiveIntervalElement live, OPT_Register register, int dfnbegin, int dfnend) {
OPT_Instruction end = live.getEnd();
if (end != null && end.operator == IA32_FMOV) {
if (dfnend == dfnbegin) {
// if end, an FMOV, both begins and ends the live range,
// then end is dead. Change it to a NOP and return null.
Empty.mutate(end, NOP);
return false;
} else {
if (!end.isPEI()) {
if (VM.VerifyAssertions) {
OPT_Operand value = MIR_Move.getValue(end);
VM._assert(value.isRegister());
VM._assert(MIR_Move.getValue(end).asRegister().getRegister() == register);
}
end.operator = IA32_FMOV_ENDING_LIVE_RANGE;
}
}
}
return true;
}