SIL: add block/instruction/value set variants which maintain their current size.

Author: eeckstein

include/swift/SIL/BasicBlockBits.h

@@ -89,6 +89,8 @@ class BasicBlockSet {
   BasicBlockFlag flag;
 
 public:
+  using Element = SILBasicBlock *;
+
   BasicBlockSet(SILFunction *function) : flag(function) {}
 
   SILFunction *getFunction() const { return flag.getFunction(); }
@@ -101,6 +103,8 @@ class BasicBlockSet {
   void erase(SILBasicBlock *block) { flag.reset(block); }
 };
 
+using BasicBlockSetWithSize = KnownSizeSet<BasicBlockSet>;
+
 } // namespace swift
 
 #endif

include/swift/SIL/NodeBits.h

@@ -94,6 +94,8 @@ class InstructionSet {
   NodeSet nodeSet;
 
 public:
+  using Element = SILInstruction *;
+
   InstructionSet(SILFunction *function) : nodeSet(function) {}
 
   SILFunction *getFunction() const { return nodeSet.getFunction(); }
@@ -106,13 +108,17 @@ class InstructionSet {
   void erase(SILInstruction *inst) { nodeSet.erase(inst->asSILNode()); }
 };
 
+using InstructionSetWithSize = KnownSizeSet<InstructionSet>;
+
 /// A set of SILValues.
 ///
 /// For details see NodeBitfield.
 class ValueSet {
   NodeSet nodeSet;
 
 public:
+  using Element = SILValue;
+
   ValueSet(SILFunction *function) : nodeSet(function) {}
 
   SILFunction *getFunction() const { return nodeSet.getFunction(); }
@@ -125,6 +131,8 @@ class ValueSet {
   void erase(SILValue value) { nodeSet.erase(value); }
 };
 
+using ValueSetWithSize = KnownSizeSet<ValueSet>;
+
 } // namespace swift
 
 #endif

include/swift/SIL/SILBitfield.h

@@ -108,6 +108,43 @@ template <class Impl, class T> class SILBitfield {
   }
 };
 
+/// A set which knowns its size.
+///
+/// This template adds a size property to a base `Set`.
+template <class Set>
+class KnownSizeSet {
+  Set set;
+  size_t numElements = 0;
+public:
+  using Element = typename Set::Element;
+
+  KnownSizeSet(SILFunction *function) : set(function) {}
+
+  SILFunction *getFunction() const { return set.getFunction(); }
+
+  bool contains(Element element) const { return set.contains(element); }
+
+  /// Returns true if \p value was not contained in the set before inserting.
+  bool insert(Element element) {
+    if (set.insert(element)) {
+      numElements += 1;
+      return true;
+    }
+    return false;
+  }
+
+  void erase(Element element) {
+    if (contains(element)) {
+      set.erase(element);
+      assert(numElements > 0);
+      numElements -= 1;
+    }
+  }
+
+  bool empty() const { return numElements == 0; }
+  
+  size_t size() const { return numElements; }
+};
 
 } // namespace swift