+ /// Query Liveness at Idx.
+ /// The sub-instruction slot of Idx doesn't matter, only the instruction
+ /// it refers to is considered.
+ LiveQueryResult Query(SlotIndex Idx) const {
+ // Find the segment that enters the instruction.
+ const_iterator I = find(Idx.getBaseIndex());
+ const_iterator E = end();
+ if (I == E)
+ return LiveQueryResult(nullptr, nullptr, SlotIndex(), false);
+
+ // Is this an instruction live-in segment?
+ // If Idx is the start index of a basic block, include live-in segments
+ // that start at Idx.getBaseIndex().
+ VNInfo *EarlyVal = nullptr;
+ VNInfo *LateVal = nullptr;
+ SlotIndex EndPoint;
+ bool Kill = false;
+ if (I->start <= Idx.getBaseIndex()) {
+ EarlyVal = I->valno;
+ EndPoint = I->end;
+ // Move to the potentially live-out segment.
+ if (SlotIndex::isSameInstr(Idx, I->end)) {
+ Kill = true;
+ if (++I == E)
+ return LiveQueryResult(EarlyVal, LateVal, EndPoint, Kill);
+ }
+ // Special case: A PHIDef value can have its def in the middle of a
+ // segment if the value happens to be live out of the layout
+ // predecessor.
+ // Such a value is not live-in.
+ if (EarlyVal->def == Idx.getBaseIndex())
+ EarlyVal = nullptr;
+ }
+ // I now points to the segment that may be live-through, or defined by
+ // this instr. Ignore segments starting after the current instr.
+ if (!SlotIndex::isEarlierInstr(Idx, I->start)) {
+ LateVal = I->valno;
+ EndPoint = I->end;
+ }
+ return LiveQueryResult(EarlyVal, LateVal, EndPoint, Kill);
+ }
+
+ /// removeValNo - Remove all the segments defined by the specified value#.