Updating check for empty debug ranges

src/coreclr/jit/codegencommon.cpp

@@ -8775,12 +8775,14 @@ void CodeGenInterface::VariableLiveKeeper::VariableLiveDescriptor::startLiveRang
 
 //------------------------------------------------------------------------
 // isLastRangeEmpty: Returns whether the last live range [A,B) is empty,
-//  meaning A == B.
+//  meaning A == B. This is an approximation as instructions may be removed
+//  after being emitted.
 //
 bool CodeGenInterface::VariableLiveKeeper::VariableLiveDescriptor::isLastRangeEmpty() const
 {
     return !m_VariableLiveRanges->empty() &&
-           m_VariableLiveRanges->back().m_StartEmitLocation == m_VariableLiveRanges->back().m_EndEmitLocation;
+           m_VariableLiveRanges->back().m_StartEmitLocation.noDistanceWith(
+               m_VariableLiveRanges->back().m_EndEmitLocation);
 }
 
 //------------------------------------------------------------------------

src/coreclr/jit/emit.cpp

@@ -91,6 +91,29 @@ bool emitLocation::IsLessOneInsAway(emitter* emit) const
     return false;
 }
 
+//------------------------------------------------------------------------
+// noDistanceWith: Returns true if no instruction was emitted between
+// both locations. This response is an approximation. There might be emitted
+// instructions that were removed after the emitLocatiosn were generated.
+//
+// Arguments:
+//  loc - an emitLocation instance
+//
+// Assumptions:
+//  this emitLocation was captured before loc.
+bool emitLocation::noDistanceWith(emitLocation& loc) const
+{
+    assert(Valid());
+    assert(loc.Valid());
+    // Spanning an IG boundary?
+    if (ig->igNext == loc.ig)
+    {
+        return (emitGetInsNumFromCodePos(codePos) == ig->igInsCnt) && (emitGetInsNumFromCodePos(loc.codePos) == 0);
+    }
+    // otherwise
+    return this->operator==(loc);
+}
+
 #ifdef DEBUG
 void emitLocation::Print(LONG compMethodID) const
 {

src/coreclr/jit/emit.h

@@ -191,6 +191,7 @@ class emitLocation
     UNATIVE_OFFSET GetFuncletPrologOffset(emitter* emit) const;
 
     bool IsLessOneInsAway(emitter* emit) const;
+    bool noDistanceWith(emitLocation& lhs) const;
 
 #ifdef DEBUG
     void Print(LONG compMethodID) const;