IRGen: Various minor fixes

lib/IRGen/GenPack.cpp

@@ -381,6 +381,7 @@ static void emitPackExpansionPack(
   IGF.Builder.CreateCondBr(cond, loop, rest);
 
   IGF.Builder.emitBlock(loop);
+  ConditionalDominanceScope condition(IGF);
 
   auto *element = elementForIndex(phi);
 
@@ -824,6 +825,8 @@ llvm::Value *irgen::emitTypeMetadataPackElementRef(
     // (1) Emit check_i {{
     IGF.Builder.emitBlock(checkBounds);
 
+    ConditionalDominanceScope dominanceScope(IGF);
+
     // The upper bound for the current pack expansion.  Exclusive.
     llvm::Value *upperBound = nullptr;
     llvm::Value *condition = nullptr;

lib/IRGen/GenTuple.cpp

@@ -565,7 +565,10 @@ Address irgen::projectTupleElementAddressByDynamicIndex(IRGenFunction &IGF,
   llvm::Value *offset = loadTupleOffsetFromMetadata(IGF, metadata, index);
   auto *gep =
       IGF.emitByteOffsetGEP(tuple.getAddress(), offset, IGF.IGM.OpaqueTy);
-  return Address(gep, IGF.IGM.OpaqueTy, IGF.IGM.getPointerAlignment());
+  auto elementAddress = Address(gep, IGF.IGM.OpaqueTy,
+                                IGF.IGM.getPointerAlignment());
+  return IGF.Builder.CreateElementBitCast(elementAddress,
+                                          IGF.IGM.getStorageType(elementType));
 }
 
 Optional<Size> irgen::getFixedTupleElementOffset(IRGenModule &IGM,

lib/IRGen/GenType.cpp

@@ -1966,14 +1966,14 @@ const TypeInfo &TypeConverter::getCompleteTypeInfo(CanType T) {
 }
 
 ArchetypeType *TypeConverter::getExemplarArchetype(ArchetypeType *t) {
-  // Get the primary archetype.
-  auto root = t->getRoot();
-
-  // If there is no primary (IOW, it's an opened archetype), the archetype is
-  // an exemplar.
-  if (!isa<PrimaryArchetypeType>(root) && !isa<VariadicSequenceType>(root))
+  if (isa<LocalArchetypeType>(t) || isa<OpaqueTypeArchetypeType>(t))
     return t;
 
+  assert(isa<PrimaryArchetypeType>(t) || isa<PackArchetypeType>(t));
+
+  // Get the root archetype.
+  auto root = t->getRoot();
+
   // Retrieve the generic environment of the archetype.
   auto genericEnv = root->getGenericEnvironment();
 

test/IRGen/pack_archetype_canonicalization.swift

@@ -0,0 +1,15 @@
+// RUN: %target-swift-frontend -emit-ir %s -enable-experimental-feature VariadicGenerics
+
+// Because of -enable-experimental-feature VariadicGenerics
+// REQUIRES: asserts
+
+// This would crash.
+public struct G<T> {}
+
+public struct GG<each T> {
+  public var variables: (repeat G<each T>)
+
+  public init() {
+    fatalError()
+  }
+}