SIL: add some Function APIs

* `isReferencedInModule`
* `shouldOptimize`

Author: eeckstein

SwiftCompilerSources/Sources/SIL/Function.swift

@@ -36,6 +36,14 @@ final public class Function : CustomStringConvertible, HasShortDescription, Hash
     hasher.combine(ObjectIdentifier(self))
   }
 
+  /// True if this function is referenced from anywhere within the module,
+  /// e.g. from a `function_ref` instruction.
+  public var isReferencedInModule: Bool { bridged.isReferencedInModule() }
+
+  /// True if this function should be optimized, i.e. the module is compiled with optimizations
+  /// and the function has no `@_optimize(none)` attribute.
+  public var shouldOptimize: Bool { bridged.shouldOptimize() }
+
   public var wasDeserializedCanonical: Bool { bridged.wasDeserializedCanonical() }
 
   public var isTrapNoReturn: Bool { bridged.isTrapNoReturn() }

include/swift/SIL/SILBridging.h

@@ -514,6 +514,8 @@ struct BridgedFunction {
   BRIDGED_INLINE ThunkKind isThunk() const;
   BRIDGED_INLINE void setThunk(ThunkKind) const;
   BRIDGED_INLINE bool needsStackProtection() const;
+  BRIDGED_INLINE bool shouldOptimize() const;
+  BRIDGED_INLINE bool isReferencedInModule() const;
   BRIDGED_INLINE bool wasDeserializedCanonical() const;
   BRIDGED_INLINE void setNeedStackProtection(bool needSP) const;
   BRIDGED_INLINE void setIsPerformanceConstraint(bool isPerfConstraint) const;

include/swift/SIL/SILBridgingImpl.h

@@ -844,6 +844,14 @@ bool BridgedFunction::needsStackProtection() const {
   return getFunction()->needsStackProtection();
 }
 
+bool BridgedFunction::shouldOptimize() const {
+  return getFunction()->shouldOptimize();
+}
+
+bool BridgedFunction::isReferencedInModule() const {
+  return getFunction()->getRefCount() != 0;
+}
+
 bool BridgedFunction::wasDeserializedCanonical() const {
   return getFunction()->wasDeserializedCanonical();
 }