[FieldSensitivePL] NFC: Added initDef(bit vector).

The new overload iterates over the contiguous ranges in the bit vector
and calls through to the overload that takes a range.

Author: nate-chandler

include/swift/SIL/FieldSensitivePrunedLiveness.h

@@ -321,6 +321,10 @@ struct TypeTreeLeafTypeRange {
       SmallVectorImpl<std::pair<SILValue, TypeTreeLeafTypeRange>>
           &resultingProjections);
 
+  static void visitContiguousRanges(
+      SmallBitVector const &bits,
+      llvm::function_ref<void(TypeTreeLeafTypeRange)> callback);
+
   bool operator==(const TypeTreeLeafTypeRange &other) const {
     return startEltOffset == other.startEltOffset &&
            endEltOffset == other.endEltOffset;
@@ -1216,6 +1220,11 @@ class FieldSensitiveMultiDefPrunedLiveRange
     defBlocks.setFrozen();
   }
 
+  void initializeDef(SILInstruction *def, SmallBitVector const &bits) {
+    TypeTreeLeafTypeRange::visitContiguousRanges(
+        bits, [&](auto range) { initializeDef(def, range); });
+  }
+
   void initializeDef(SILValue def, TypeTreeLeafTypeRange span) {
     assert(Super::isInitialized());
     defs.insert(def, span);

lib/SIL/Utils/FieldSensitivePrunedLiveness.cpp

@@ -465,6 +465,31 @@ void TypeTreeLeafTypeRange::constructProjectionsForNeededElements(
   }
 }
 
+void TypeTreeLeafTypeRange::visitContiguousRanges(
+    SmallBitVector const &bits,
+    llvm::function_ref<void(TypeTreeLeafTypeRange)> callback) {
+  if (bits.size() == 0)
+    return;
+
+  Optional<std::pair<unsigned, /*isSet*/ bool>> current = llvm::None;
+  for (unsigned bit = 0, size = bits.size(); bit < size; ++bit) {
+    auto isSet = bits.test(bit);
+    if (!current) {
+      current = {bit, isSet};
+      continue;
+    }
+    if (current->second != isSet) {
+      if (current->second) {
+        callback(TypeTreeLeafTypeRange(current->first, bit));
+      }
+      current = {bit, isSet};
+    }
+  }
+  if (current->second) {
+    callback(TypeTreeLeafTypeRange(current->first, bits.size()));
+  }
+}
+
 //===----------------------------------------------------------------------===//
 //                    MARK: FieldSensitivePrunedLiveBlocks
 //===----------------------------------------------------------------------===//