// Using LiveOutCache as a visited set, perform a BFS for all reaching defs.
for (unsigned i = 0; i != LiveIn.size(); ++i) {
MachineBasicBlock *MBB = LiveIn[i]->getBlock();
+ assert(!MBB->pred_empty() && "Value live-in to entry block?");
for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
PE = MBB->pred_end(); PI != PE; ++PI) {
MachineBasicBlock *Pred = *PI;
}
SlotIndex Idx = LIS.getInstructionIndex(MI);
- Idx = MO.isUse() ? Idx.getUseIndex() : Idx.getDefIndex();
+ if (MO.isDef())
+ Idx = MO.isEarlyClobber() ? Idx.getUseIndex() : Idx.getDefIndex();
// Rewrite to the mapped register at Idx.
unsigned RegIdx = RegAssign.lookup(Idx);
DEBUG(dbgs() << " rewr BB#" << MI->getParent()->getNumber() << '\t'
<< Idx << ':' << RegIdx << '\t' << *MI);
- // Extend liveness to Idx.
- if (ExtendRanges)
- extendRange(RegIdx, Idx);
+ // Extend liveness to Idx if the instruction reads reg.
+ if (!ExtendRanges)
+ continue;
+
+ // Skip instructions that don't read Reg.
+ if (MO.isDef()) {
+ if (!MO.getSubReg() && !MO.isEarlyClobber())
+ continue;
+ // We may wan't to extend a live range for a partial redef, or for a use
+ // tied to an early clobber.
+ Idx = Idx.getPrevSlot();
+ if (!Edit->getParent().liveAt(Idx))
+ continue;
+ } else
+ Idx = Idx.getUseIndex();
+
+ extendRange(RegIdx, Idx);
}
}