SILGen: Peephole existential-to-Any upcasts too.

Recognize an erasure of an opened existential and look through it.

Author: jckarter

lib/SILGen/SILGenApply.cpp

@@ -3086,18 +3086,39 @@ namespace {
 
     }
 
+    Expr *lookThroughExistentialErasures(Expr *argExpr) {
+      argExpr = argExpr->getSemanticsProvidingExpr();
+
+      // When converting from an existential type to a more general existential,
+      // the inner existential is opened first. Look through this pattern.
+      if (auto open = dyn_cast<OpenExistentialExpr>(argExpr)) {
+        auto subExpr = open->getSubExpr()->getSemanticsProvidingExpr();
+        while (auto erasure = dyn_cast<ErasureExpr>(subExpr)) {
+          subExpr = erasure->getSubExpr()->getSemanticsProvidingExpr();
+        }
+        // If we drilled down to the underlying opened existential, look
+        // through it.
+        if (subExpr == open->getOpaqueValue())
+          return open->getExistentialValue();
+        // TODO: Maybe there are other peepholes we could attempt on opened
+        // existentials?
+        return open;
+      }
+      
+      // Look through ErasureExprs and try to bridge the underlying
+      // concrete value instead.
+      while (auto erasure = dyn_cast<ErasureExpr>(argExpr))
+        argExpr = erasure->getSubExpr()->getSemanticsProvidingExpr();
+      return argExpr;
+    }
+    
     /// Emit an argument expression that we know will be bridged to an
     /// Objective-C object.
     ManagedValue emitNativeToBridgedObjectArgument(Expr *argExpr,
                                                SILType loweredSubstArgType,
                                                AbstractionPattern origParamType,
                                                SILParameterInfo param) {
-      argExpr = argExpr->getSemanticsProvidingExpr();
-      
-      // Look through ErasureExprs and try to bridge the underlying
-      // concrete value instead.
-      while (auto erasure = dyn_cast<ErasureExpr>(argExpr))
-        argExpr = erasure->getSubExpr();
+      argExpr = lookThroughExistentialErasures(argExpr);
 
       // Emit the argument.
       auto contexts = getRValueEmissionContexts(loweredSubstArgType, param);

test/SILGen/objc_bridging_any.swift

@@ -16,29 +16,34 @@ func passingToId<T: CP, U>(receiver: IdLover,
                            generic: U,
                            existential: P,
                            any: Any) {
-  // CHECK: [[METHOD:%.*]] = class_method [volatile] [[SELF:%.*]] : $IdLover,
+  // CHECK: bb0([[SELF:%.*]] : $IdLover, [[STRING:%.*]] : $String, [[NSSTRING:%.*]] : $NSString, [[OBJECT:%.*]] : $AnyObject, [[CLASS_GENERIC:%.*]] : $T, [[CLASS_EXISTENTIAL:%.*]] : $CP
+
+  // CHECK: [[METHOD:%.*]] = class_method [volatile] [[SELF]]
   // CHECK: [[BRIDGE_STRING:%.*]] = function_ref @_TFE10FoundationSS19_bridgeToObjectiveC
-  // CHECK: [[NSSTRING:%.*]] = apply [[BRIDGE_STRING]]
-  // CHECK: [[ANYOBJECT:%.*]] = init_existential_ref [[NSSTRING]] : $NSString : $NSString, $AnyObject
+  // CHECK: [[BRIDGED:%.*]] = apply [[BRIDGE_STRING]]([[STRING]])
+  // CHECK: [[ANYOBJECT:%.*]] = init_existential_ref [[BRIDGED]] : $NSString : $NSString, $AnyObject
   // CHECK: apply [[METHOD]]([[ANYOBJECT]], [[SELF]])
   receiver.takesId(string)
 
-  // CHECK: [[METHOD:%.*]] = class_method [volatile] [[SELF:%.*]] : $IdLover,
-  // CHECK: [[ANYOBJECT:%.*]] = init_existential_ref {{%.*}} : $NSString : $NSString, $AnyObject
+  // CHECK: [[METHOD:%.*]] = class_method [volatile] [[SELF]] : $IdLover,
+  // CHECK: [[ANYOBJECT:%.*]] = init_existential_ref [[NSSTRING]] : $NSString : $NSString, $AnyObject
   // CHECK: apply [[METHOD]]([[ANYOBJECT]], [[SELF]])
   receiver.takesId(nsString)
 
-  // CHECK: [[METHOD:%.*]] = class_method [volatile] [[SELF:%.*]] : $IdLover,
-  // CHECK: [[ANYOBJECT:%.*]] = init_existential_ref {{%.*}} : $T : $T, $AnyObject
+  // CHECK: [[METHOD:%.*]] = class_method [volatile] [[SELF]] : $IdLover,
+  // CHECK: [[ANYOBJECT:%.*]] = init_existential_ref [[CLASS_GENERIC]] : $T : $T, $AnyObject
   // CHECK: apply [[METHOD]]([[ANYOBJECT]], [[SELF]])
   receiver.takesId(classGeneric)
 
-  // TODO: Need to look through an (open_existential (erasure)) combo to upcast
-  // an existential to Any.
-  /*
+  // CHECK: [[METHOD:%.*]] = class_method [volatile] [[SELF]] : $IdLover,
+  // CHECK: apply [[METHOD]]([[OBJECT]], [[SELF]])
   receiver.takesId(object)
+
+  // CHECK: [[METHOD:%.*]] = class_method [volatile] [[SELF]] : $IdLover,
+  // CHECK: [[OPENED:%.*]] = open_existential_ref [[CLASS_EXISTENTIAL]] : $CP
+  // CHECK: [[ANYOBJECT:%.*]] = init_existential_ref [[OPENED]]
+  // CHECK: apply [[METHOD]]([[ANYOBJECT]], [[SELF]])
   receiver.takesId(classExistential)
-   */
 
   // TODO: These cases need to perform a (to-be-implemented) universal
   // bridging conversion.