Subzero: Optimize a common live range overlap calculation.

src/IceOperand.cpp

Index: src/IceOperand.cpp
diff --git a/src/IceOperand.cpp b/src/IceOperand.cpp
index 26ef83089a064191b569fa88b0b34effbe4c94bc..c366dd993558f604ff6ddf7b441b5350e7c5a36c 100644
--- a/src/IceOperand.cpp
+++ b/src/IceOperand.cpp
@@ -37,6 +37,8 @@ bool operator==(const RegWeight &A, const RegWeight &B) {
 }
 
 void LiveRange::addSegment(InstNumberT Start, InstNumberT End) {
+  if (End > Start)
+    IsNonpoints = true;
 #ifdef USE_SET
   RangeElementType Element(Start, End);
   RangeType::iterator Next = Range.lower_bound(Element);
@@ -122,6 +124,8 @@ bool LiveRange::overlaps(const LiveRange &Other) const {
 }
 
 bool LiveRange::overlaps(InstNumberT OtherBegin) const {
+  if (!IsNonpoints)
+    return false;
   bool Result = false;
   for (const RangeElementType &I : Range) {
     if (OtherBegin < I.first) {