DEBUG(dbgs() << TRI->getName(RC->getRegister(rx)) << ":\t" << CurInstr
<< '\t' << *MI);
+ // How many instructions since rx was last written?
+ unsigned Clearance = CurInstr - LiveRegs[rx].Def;
LiveRegs[rx].Def = CurInstr;
// Kill off domains redefined by generic instructions.
if (Kill)
kill(rx);
+
+ // Verify clearance before partial register updates.
+ unsigned Pref = TII->getPartialRegUpdateClearance(MI, i, TRI);
+ if (!Pref)
+ continue;
+ DEBUG(dbgs() << "Clearance: " << Clearance << ", want " << Pref);
+ if (Pref > Clearance) {
+ DEBUG(dbgs() << ": Break dependency.\n");
+ TII->breakPartialRegDependency(MI, i, TRI);
+ continue;
+ }
+
+ // The current clearance seems OK, but we may be ignoring a def from a
+ // back-edge.
+ if (!SeenUnknownBackEdge || Pref <= unsigned(CurInstr)) {
+ DEBUG(dbgs() << ": OK.\n");
+ continue;
+ }
+
+ // A def from an unprocessed back-edge may make us break this dependency.
+ DEBUG(dbgs() << ": Wait for back-edge to resolve.\n");
}
++CurInstr;
for (unsigned i = 0, e = Loops.size(); i != e; ++i) {
MachineBasicBlock *MBB = Loops[i];
enterBasicBlock(MBB);
+ for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); I != E;
+ ++I)
+ if (!I->isDebugValue())
+ processDefs(I, false);
leaveBasicBlock(MBB);
}