AST: Factor out GenericSignatureImpl::getShapeClasses()

Author: slavapestov

include/swift/AST/GenericSignature.h

@@ -432,6 +432,9 @@ class alignas(1 << TypeAlignInBits) GenericSignatureImpl final
   /// the same shape equivalence class.
   bool haveSameShape(Type type1, Type type2) const;
 
+  /// Returns all unique shape classes defined by this generic signature.
+  SmallVector<CanType, 2> getShapeClasses() const;
+
   /// Get the ordinal of a generic parameter in this generic signature.
   ///
   /// For example, if you have a generic signature for a nested context like:

lib/AST/GenericSignature.cpp

@@ -544,6 +544,19 @@ GenericSignatureImpl::haveSameShape(Type type1, Type type2) const {
   return getRequirementMachine()->haveSameShape(type1, type2);
 }
 
+SmallVector<CanType, 2> GenericSignatureImpl::getShapeClasses() const {
+  SmallSetVector<CanType, 2> result;
+
+  forEachParam([&](GenericTypeParamType *gp, bool canonical) {
+    if (!canonical || !gp->isParameterPack())
+      return;
+
+    result.insert(getReducedShape(gp)->getCanonicalType());
+  });
+
+  return result.takeVector();
+}
+
 unsigned GenericParamKey::findIndexIn(
                       TypeArrayView<GenericTypeParamType> genericParams) const {
   // For depth 0, we have random access. We perform the extra checking so that

lib/IRGen/GenProto.cpp

@@ -258,15 +258,7 @@ irgen::enumerateGenericSignatureRequirements(CanGenericSignature signature,
                                           const RequirementCallback &callback) {
   if (!signature) return;
 
-  // Get all unique pack generic parameter shapes.
-  SmallSetVector<CanType, 2> packs;
-  for (auto gp : signature.getGenericParams()) {
-    if (gp->isParameterPack()) {
-      packs.insert(signature->getReducedShape(gp)->getCanonicalType());
-    }
-  }
-
-  for (auto type : packs)
+  for (auto type : signature->getShapeClasses())
     callback(GenericRequirement::forShape(type));
 
   // Get all of the type metadata.