[SafeStack,NFC] Cleanup LiveRange interface

lib/CodeGen/SafeStack.cpp

@@ -498,7 +498,7 @@ Value *SafeStack::moveStaticAllocasToUnsafeStack(
   DIBuilder DIB(*F.getParent());
 
   StackColoring SSC(F, StaticAllocas);
-  static const StackColoring::LiveRange NoColoringRange = {BitVector{1, true}};
+  static const StackColoring::LiveRange NoColoringRange(1, true);
   if (ClColoring)
     SSC.run();
   SSC.removeAllMarkers();

lib/CodeGen/SafeStackColoring.cpp

@@ -275,14 +275,12 @@ StackColoring::StackColoring(const Function &F,
 
   for (unsigned I = 0; I < NumAllocas; ++I)
     AllocaNumbering[Allocas[I]] = I;
-  LiveRanges.resize(NumAllocas);
 
   collectMarkers();
 }
 
 void StackColoring::run() {
-  for (auto &R : LiveRanges)
-    R.SetMaximum(NumInst);
+  LiveRanges.resize(NumAllocas, LiveRange(NumInst));
   for (unsigned I = 0; I < NumAllocas; ++I)
     if (!InterestingAllocas.test(I))
       LiveRanges[I] = getFullLiveRange();

lib/CodeGen/SafeStackColoring.h

@@ -59,17 +59,20 @@ class StackColoring {
 public:
   /// This class represents a set of interesting instructions where an alloca is
   /// live.
-  struct LiveRange {
-    BitVector bv;
+  class LiveRange {
+    BitVector Bits;
+    friend raw_ostream &operator<<(raw_ostream &OS,
+                                   const StackColoring::LiveRange &R);
 
-    void SetMaximum(int size) { bv.resize(size); }
-    void AddRange(unsigned start, unsigned end) { bv.set(start, end); }
+  public:
+    LiveRange(unsigned Size, bool Set = false) : Bits(Size, Set) {}
+    void AddRange(unsigned Start, unsigned End) { Bits.set(Start, End); }
 
     bool Overlaps(const LiveRange &Other) const {
-      return bv.anyCommon(Other.bv);
+      return Bits.anyCommon(Other.Bits);
     }
 
-    void Join(const LiveRange &Other) { bv |= Other.bv; }
+    void Join(const LiveRange &Other) { Bits |= Other.Bits; }
   };
 
 private:
@@ -133,10 +136,7 @@ public:
   /// entire function.
   LiveRange getFullLiveRange() const {
     assert(NumInst >= 0);
-    LiveRange R;
-    R.SetMaximum(NumInst);
-    R.AddRange(0, NumInst);
-    return R;
+    return LiveRange(NumInst, true);
   }
 };
 
@@ -156,9 +156,9 @@ static inline raw_ostream &operator<<(raw_ostream &OS, const BitVector &V) {
   return OS;
 }
 
-static inline raw_ostream &operator<<(raw_ostream &OS,
-                                      const StackColoring::LiveRange &R) {
-  return OS << R.bv;
+inline raw_ostream &operator<<(raw_ostream &OS,
+                               const StackColoring::LiveRange &R) {
+  return OS << R.Bits;
 }
 
 } // end namespace safestack

lib/CodeGen/SafeStackLayout.cpp

@@ -95,7 +95,7 @@ void StackLayout::layoutObject(StackObject &Obj) {
     if (Start > LastRegionEnd) {
       LLVM_DEBUG(dbgs() << "  Creating gap region: " << LastRegionEnd << " .. "
                         << Start << "\n");
-      Regions.emplace_back(LastRegionEnd, Start, StackColoring::LiveRange());
+      Regions.emplace_back(LastRegionEnd, Start, StackColoring::LiveRange(0));
       LastRegionEnd = Start;
     }
     LLVM_DEBUG(dbgs() << "  Creating new region: " << LastRegionEnd << " .. "