Shrink wrapping in PEI:

- reduces _static_ callee saved register spills
  and restores similar to Chow's original algorithm.
- iterative implementation with simple heuristic
  limits to mitigate compile time impact.
- handles placing spills/restores for multi-entry,
  multi-exit regions in the Machine CFG without
  splitting edges.
- passes test-suite in LLCBETA mode.

Added contains() method to ADT/SparseBitVector.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71438 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ADT/SparseBitVector.h

@@ -641,8 +641,8 @@ public:
     return changed;
   }
 
-  // Intersect our bitmap with the complement of the RHS and return true if ours
+  // Intersect our bitmap with the complement of the RHS and return true
-  // changed.
+  // if ours changed.
   bool intersectWithComplement(const SparseBitVector &RHS) {
     bool changed = false;
     ElementListIter Iter1 = Elements.begin();
@@ -685,8 +685,8 @@ public:
   }
 
 
-  //  Three argument version of intersectWithComplement.  Result of RHS1 & ~RHS2
+  //  Three argument version of intersectWithComplement.
-  //  is stored into this bitmap.
+  //  Result of RHS1 & ~RHS2 is stored into this bitmap.
   void intersectWithComplement(const SparseBitVector<ElementSize> &RHS1,
                                const SparseBitVector<ElementSize> &RHS2)
   {
@@ -775,6 +775,14 @@ public:
     return false;
   }
 
+  // Return true iff all bits set in this SparseBitVector are
+  // also set in RHS.
+  bool contains(const SparseBitVector<ElementSize> &RHS) const {
+    SparseBitVector<ElementSize> Result(*this);
+    Result &= RHS;
+    return (Result == RHS);
+  }
+
   // Return the first set bit in the bitmap.  Return -1 if no bits are set.
   int find_first() const {
     if (Elements.empty())
@@ -875,6 +883,8 @@ operator-(const SparseBitVector<ElementSize> &LHS,
 }
 
 
+
+
 // Dump a SparseBitVector to a stream
 template <unsigned ElementSize>
 void dump(const SparseBitVector<ElementSize> &LHS, llvm::OStream &out) {