Don't naively apply the bridging peephole to AnyObject? -> Any? -> AnyObject.

Also, fix some logic in the peephole that was incorrectly recognizing
T? -> U? -> AnyObject as a force instead of a request to create NSNull.

In both cases, we ought to still be able to do much better than the
unpeepholed code by just applying the peephole and then merging in NSNull
in the nil case, but in the short term we need to fix this bug.

Fixes rdar://35402853

Author: rjmccall

lib/SILGen/SILGenBridging.cpp

@@ -632,6 +632,13 @@ static ManagedValue emitNativeToCBridgedNonoptionalValue(SILGenFunction &SGF,
                                  loweredBridgedTy.castTo<SILFunctionType>());
   }
 
+  // Erase IUO at this point, because there aren't any conformances for
+  // IUO anymore.  Note that the value representation stays the same
+  // because SIL erases the difference.
+  if (auto obj = nativeType->getImplicitlyUnwrappedOptionalObjectType()) {
+    nativeType = OptionalType::get(obj)->getCanonicalType();
+  }
+
   // If the native type conforms to _ObjectiveCBridgeable, use its
   // _bridgeToObjectiveC witness.
   if (auto conformance =

lib/SILGen/SILGenConvert.cpp

@@ -1272,6 +1272,23 @@ static bool isValueToAnyConversion(CanType from, CanType to) {
   return !from->isAnyClassReferenceType();
 }
 
+/// Check whether this conversion is Any??? to AnyObject???.  If the result
+/// type is less optional, it doesn't count.
+static bool isMatchedAnyToAnyObjectConversion(CanType from, CanType to) {
+  while (auto fromObject = from.getAnyOptionalObjectType()) {
+    auto toObject = to.getAnyOptionalObjectType();
+    if (!toObject) return false;
+    from = fromObject;
+    to = toObject;
+  }
+
+  if (from->isAny()) {
+    assert(to->isAnyObject());
+    return true;
+  }
+  return false;
+}
+
 Optional<ConversionPeepholeHint>
 Lowering::canPeepholeConversions(SILGenFunction &SGF,
                                  const Conversion &outerConversion,
@@ -1332,8 +1349,7 @@ Lowering::canPeepholeConversions(SILGenFunction &SGF,
 
       // Converting to Any doesn't do anything semantically special, so we
       // can apply the peephole unconditionally.
-      if (intermediateType->lookThroughAllAnyOptionalTypes()->isAny()) {
-        assert(resultType->lookThroughAllAnyOptionalTypes()->isAnyObject());
+      if (isMatchedAnyToAnyObjectConversion(intermediateType, resultType)) {
         if (loweredSourceTy == loweredResultTy) {
           return applyPeephole(ConversionPeepholeHint::Identity);
         } else if (isValueToAnyConversion(sourceType, intermediateType)) {
@@ -1375,7 +1391,8 @@ Lowering::canPeepholeConversions(SILGenFunction &SGF,
       if (!forced &&
           innerConversion.getKind() == Conversion::BridgeResultFromObjC) {
         if (auto sourceValueType = sourceType.getAnyOptionalObjectType()) {
-          if (areRelatedTypesForBridgingPeephole(sourceValueType, resultType)) {
+          if (!intermediateType.getAnyOptionalObjectType() &&
+              areRelatedTypesForBridgingPeephole(sourceValueType, resultType)) {
             forced = true;
             return applyPeephole(ConversionPeepholeHint::Subtype);
           }

test/Inputs/clang-importer-sdk/usr/include/Foundation.h

@@ -1140,3 +1140,5 @@ void install_global_event_handler(_Nullable event_handler handler);
          forKeyPath: (NSString*) keyPath
          context: (void*) options;
 @end
+
+__nullable id returnNullableId(void);

test/SILGen/objc_bridging_peephole.swift

@@ -115,17 +115,27 @@ func testForcedMethodResult(dummy: DummyClass) {
   // CHECK-NEXT: apply [[USE]]([[RESULT]])
   useNS(dummy.fetchNullproneString() as NSString)
 
+  //   This is not a force.
+  //   TODO: we could do it more efficiently than this, though
   // CHECK:      [[SELF:%.*]] = begin_borrow %0
   // CHECK-NEXT: [[METHOD:%.*]] = objc_method
   // CHECK-NEXT: [[RESULT:%.*]] = apply [[METHOD]]([[SELF]])
   // CHECK-NEXT: end_borrow [[SELF]] from %0
   // CHECK-NEXT: switch_enum [[RESULT]]
-  // CHECK:    bb3:
-  // CHECK:      function_ref @_T0s30_diagnoseUnexpectedNilOptionalyBp14_filenameStart_Bw01_E6LengthBi1_01_E7IsASCIIBw5_linetF
-  // CHECK:    bb4([[RESULT:%.*]] : @owned $NSString):
-  // CHECK-NEXT: [[ANYOBJECT:%.*]] = init_existential_ref [[RESULT]] : $NSString : $NSString, $AnyObject
+  // CHECK:    bb3([[RESULT:%.*]] : @owned $NSString):
+  // CHECK:      function_ref @_T0SS10FoundationE36_unconditionallyBridgeFromObjectiveCSSSo8NSStringCSgFZ
+  // CHECK:    bb4:
+  // CHECK:      enum $Optional<String>, #Optional.none
+  // CHECK:    bb5([[OPTSTRING:%.*]] : @owned $Optional<String>):
+  // CHECK:      [[BRIDGE:%.*]] = function_ref @_T0Sq19_bridgeToObjectiveCyXlyF
+  // CHECK-NEXT: [[TEMP:%.*]] = alloc_stack $Optional<String>
+  // CHECK-NEXT: [[BORROW:%.*]] = begin_borrow [[OPTSTRING]]
+  // CHECK-NEXT: store_borrow [[BORROW]] to [[TEMP]] : $*Optional<String>
+  // CHECK-NEXT: [[ANYOBJECT:%.*]] = apply [[BRIDGE]]<String>([[TEMP]])
   // CHECK:      [[USE:%.*]] = function_ref @_T022objc_bridging_peephole12useAnyObjectyyXlF
   // CHECK-NEXT: apply [[USE]]([[ANYOBJECT]])
+  // CHECK-NEXT: end_borrow [[BORROW]] from [[OPTSTRING]]
+  // CHECK-NEXT: dealloc_stack [[TEMP]]
   useAnyObject(dummy.fetchNullproneString() as AnyObject)
 
   // CHECK:      return
@@ -233,16 +243,27 @@ func testForcedPropertyValue(dummy: DummyClass) {
   // CHECK-NEXT: end_borrow [[SELF]] from %0
   useNS(dummy.nullproneStringProperty as NSString)
 
+  //   This is not a force.
+  //   TODO: we could do it more efficiently than this, though
   // CHECK-NEXT: [[SELF:%.*]] = begin_borrow %0
   // CHECK-NEXT: [[METHOD:%.*]] = objc_method
   // CHECK-NEXT: [[RESULT:%.*]] = apply [[METHOD]]([[SELF]])
   // CHECK-NEXT: switch_enum [[RESULT]]
-  // CHECK:    bb3:
-  // CHECK:      function_ref @_T0s30_diagnoseUnexpectedNilOptionalyBp14_filenameStart_Bw01_E6LengthBi1_01_E7IsASCIIBw5_linetF
-  // CHECK:    bb4([[RESULT:%.*]] : @owned $NSString):
-  // CHECK-NEXT: [[ANYOBJECT:%.*]] = init_existential_ref [[RESULT]] : $NSString : $NSString, $AnyObject
+  // CHECK:    bb3([[RESULT:%.*]] : @owned $NSString):
+  // CHECK:      function_ref @_T0SS10FoundationE36_unconditionallyBridgeFromObjectiveCSSSo8NSStringCSgFZ
+  // CHECK:    bb4:
+  // CHECK:      enum $Optional<String>, #Optional.none
+  // CHECK:    bb5([[OPTSTRING:%.*]] : @owned $Optional<String>):
+  // CHECK:      [[BRIDGE:%.*]] = function_ref @_T0Sq19_bridgeToObjectiveCyXlyF
+  // CHECK-NEXT: [[TEMP:%.*]] = alloc_stack $Optional<String>
+  // CHECK-NEXT: [[BORROW:%.*]] = begin_borrow [[OPTSTRING]]
+  // CHECK-NEXT: store_borrow [[BORROW]] to [[TEMP]] : $*Optional<String>
+  // CHECK-NEXT: [[ANYOBJECT:%.*]] = apply [[BRIDGE]]<String>([[TEMP]])
   // CHECK:      [[USE:%.*]] = function_ref @_T022objc_bridging_peephole12useAnyObjectyyXlF
   // CHECK-NEXT: apply [[USE]]([[ANYOBJECT]])
+  // CHECK-NEXT: end_borrow [[BORROW]] from [[OPTSTRING]]
+  // CHECK-NEXT: dealloc_stack [[TEMP]]
+  // CHECK-NEXT: destroy_value [[OPTSTRING]]
   // CHECK-NEXT: end_borrow [[SELF]] from %0
   useAnyObject(dummy.nullproneStringProperty as AnyObject)
 
@@ -627,3 +648,14 @@ protocol P {
 func foo(p: P) {
   DummyClass().takeNullableString(p.title)
 }
+
+// rdar://35402853
+//   Make sure that we don't peephole AnyObject? -> Any? -> AnyObject naively.
+// CHECK: sil hidden @_T022objc_bridging_peephole017testOptionalToNonE6BridgeyyF
+func testOptionalToNonOptionalBridge() {
+  // CHECK: apply {{.*}}() : $@convention(c) () -> @autoreleased Optional<AnyObject>
+  // CHECK: function_ref @_T0s018_bridgeAnyObjectToB0ypyXlSgF :
+  // CHECK: [[T0:%.*]] = function_ref @_T0Sq19_bridgeToObjectiveCyXlyF
+  // CHECK: apply [[T0]]<Any>
+  useAnyObject(returnNullableId() as AnyObject)
+} // CHECK: end sil function '_T022objc_bridging_peephole017testOptionalToNonE6BridgeyyF'