[Profiler] Avoid exposing the RegionCounterMap

Not sure why we ever did this, expose the counter
index via a lookup method instead.

Author: hamishknight

include/swift/SIL/SILProfiler.h

@@ -142,11 +142,13 @@ class SILProfiler : public SILAllocated<SILProfiler> {
   /// Get the number of region counters.
   unsigned getNumRegionCounters() const { return NumRegionCounters; }
 
-  /// Get the mapping from a \c ProfileCounterRef to its corresponding
-  /// profile counter.
-  const llvm::DenseMap<ProfileCounterRef, unsigned> &
-  getRegionCounterMap() const {
-    return RegionCounterMap;
+  /// Retrieve the counter index for a given counter reference, asserting that
+  /// it is present.
+  unsigned getCounterIndexFor(ProfileCounterRef ref);
+
+  /// Whether a counter has been recorded for the given counter reference.
+  bool hasCounterFor(ProfileCounterRef ref) {
+    return RegionCounterMap.contains(ref);
   }
 
 private:

lib/SIL/IR/SILProfiler.cpp

@@ -1491,3 +1491,9 @@ llvm::Optional<ASTNode> SILProfiler::getPGOParent(ASTNode Node) {
   }
   return it->getSecond();
 }
+
+unsigned SILProfiler::getCounterIndexFor(ProfileCounterRef ref) {
+  auto result = RegionCounterMap.find(ref);
+  assert(result != RegionCounterMap.end());
+  return result->second;
+}

lib/SILGen/SILGenFunction.cpp

@@ -1726,19 +1726,15 @@ void SILGenFunction::emitProfilerIncrement(ProfileCounterRef Ref) {
   if (!SP->hasRegionCounters() || !getModule().getOptions().UseProfile.empty())
     return;
 
-  const auto &RegionCounterMap = SP->getRegionCounterMap();
-  auto CounterIt = RegionCounterMap.find(Ref);
-
-  assert(CounterIt != RegionCounterMap.end() &&
-         "cannot increment non-existent counter");
+  auto CounterIdx = SP->getCounterIndexFor(Ref);
 
   // If we're at an unreachable point, the increment can be elided as the
   // counter cannot be incremented.
   if (!B.hasValidInsertionPoint())
     return;
 
   B.createIncrementProfilerCounter(
-      Ref.getLocation(), CounterIt->second, SP->getPGOFuncName(),
+      Ref.getLocation(), CounterIdx, SP->getPGOFuncName(),
       SP->getNumRegionCounters(), SP->getPGOFuncHash());
 }