SILGen: Fix some issues with @pseudogeneric thunks

This would manifest as crashes in IRGen when bridging a block
taking another block in generic context.

- When emitting a re-abstraction thunk, make it pseudogeneric if
  its parent function is pseudogeneric. This ensures we don't
  try to get runtime type metadata when it doesn't exist.

- Mangle pseudogeneric-ness of a reabstraction thunk correctly.
  Otherwise we could emit thunks with different signatures under
  the same mangling.

- Only set the pseudogeneric attribute if the thunk has a generic
  signature, since otherwise the mangling is no longer unique.

Fixes <rdar://problem/27718566>.

Author: slavapestov

lib/SILGen/SILGenBridging.cpp

@@ -341,6 +341,11 @@ ManagedValue SILGenFunction::emitFuncToBlock(SILLocation loc,
             blockInterfaceTy->getParameters().end(),
             std::back_inserter(params));
 
+  auto genericSig = F.getLoweredFunctionType()->getGenericSignature();
+  auto extInfo =
+      SILFunctionType::ExtInfo()
+        .withRepresentation(SILFunctionType::Representation::CFunctionPointer);
+
   // The block invoke function must be pseudogeneric. This should be OK for now
   // since a bridgeable function's parameters and returns should all be
   // trivially representable in ObjC so not need to exercise the type metadata.
@@ -349,17 +354,17 @@ ManagedValue SILGenFunction::emitFuncToBlock(SILLocation loc,
   // that will require a redesign of the interface to support dependent-layout
   // context. Currently we don't capture anything directly into a block but a
   // Swift closure, but that's totally dumb.
+  if (genericSig)
+    extInfo = extInfo.withIsPseudogeneric();
+
   auto invokeTy =
-    SILFunctionType::get(F.getLoweredFunctionType()->getGenericSignature(),
-                     SILFunctionType::ExtInfo()
-                       .withRepresentation(SILFunctionType::Representation::
-                                           CFunctionPointer)
-                       .withIsPseudogeneric(),
-                     ParameterConvention::Direct_Unowned,
-                     params,
-                     blockInterfaceTy->getAllResults(),
-                     blockInterfaceTy->getOptionalErrorResult(),
-                     getASTContext());
+    SILFunctionType::get(genericSig,
+                         extInfo,
+                         ParameterConvention::Direct_Unowned,
+                         params,
+                         blockInterfaceTy->getAllResults(),
+                         blockInterfaceTy->getOptionalErrorResult(),
+                         getASTContext());
 
   // Create the invoke function. Borrow the mangling scheme from reabstraction
   // thunks, which is what we are in spirit.

lib/SILGen/SILGenDecl.cpp

@@ -1973,7 +1973,7 @@ getOrCreateReabstractionThunk(GenericParamList *thunkContextParams,
     // makes the actual thunk.
     mangler.append("_TTR");
     if (auto generics = thunkType->getGenericSignature()) {
-      mangler.append('G');
+      mangler.append(thunkType->isPseudogeneric() ? 'g' : 'G');
       mangler.setModuleContext(M.getSwiftModule());
       mangler.mangleGenericSignature(generics);
     }

lib/SILGen/SILGenPoly.cpp

@@ -2377,7 +2377,12 @@ CanSILFunctionType SILGenFunction::buildThunkType(
 
   auto extInfo = expectedType->getExtInfo()
     .withRepresentation(SILFunctionType::Representation::Thin);
-  
+
+  // If our parent function was pseudogeneric, this thunk must also be
+  // pseudogeneric, since we have no way to pass generic parameters.
+  if (F.getLoweredFunctionType()->isPseudogeneric())
+    extInfo = extInfo.withIsPseudogeneric();
+
   // Map the parameter and expected types out of context to get the interface
   // type of the thunk.
   SmallVector<SILParameterInfo, 4> interfaceParams;

test/SILGen/objc_blocks_bridging.swift

@@ -136,3 +136,21 @@ func bridgeNoescapeBlock() {
   // CHECK: function_ref @_TTRXFo___XFdCb___
   noescapeNonnullBlockAlias { }
 }
+
+class ObjCClass : NSObject {}
+
+extension ObjCClass {
+  func someDynamicMethod(closure: (() -> ()) -> ()) {}
+}
+
+struct GenericStruct<T> {
+  let closure: (() -> ()) -> ()
+
+  func doStuff(o: ObjCClass) {
+    o.someDynamicMethod(closure: closure)
+  }
+}
+
+// CHECK-LABEL: sil shared [transparent] [reabstraction_thunk] @_TTRgrXFo_oXFo_____XFdCb_dXFdCb_____ : $@convention(c) @pseudogeneric <T> (@inout_aliasable @block_storage @callee_owned (@owned @callee_owned () -> ()) -> (), @convention(block) () -> ()) -> ()
+// CHECK-LABEL: sil shared [transparent] [reabstraction_thunk] @_TTRgrXFdCb___XFo___ : $@convention(thin) @pseudogeneric <T> (@owned @convention(block) () -> ()) -> ()
+

test/SILGen/objc_bridging_any.swift

@@ -422,7 +422,7 @@ class SwiftIdLover : NSObject, Anyable {
   // CHECK-NEXT:  strong_release [[RESULT]]
   // CHECK-NEXT:  return [[BLOCK]]
 
-  // CHECK-LABEL: sil shared [transparent] [reabstraction_thunk] @_TTRXFo_iP___XFdCb_dPs9AnyObject___ : $@convention(c) @pseudogeneric (@inout_aliasable @block_storage @callee_owned (@in Any) -> (), AnyObject) -> ()
+  // CHECK-LABEL: sil shared [transparent] [reabstraction_thunk] @_TTRXFo_iP___XFdCb_dPs9AnyObject___ : $@convention(c) (@inout_aliasable @block_storage @callee_owned (@in Any) -> (), AnyObject) -> ()
   // CHECK:     bb0(%0 : $*@block_storage @callee_owned (@in Any) -> (), %1 : $AnyObject):
   // CHECK-NEXT:  [[BLOCK_STORAGE_ADDR:%.*]] = project_block_storage %0
   // CHECK-NEXT:  [[FUNCTION:%.*]] = load [[BLOCK_STORAGE_ADDR]]
@@ -493,7 +493,7 @@ class SwiftIdLover : NSObject, Anyable {
   // CHECK-NEXT:  strong_release [[FUNCTION]]
   // CHECK-NEXT:  return [[BLOCK]]
 
-  // CHECK-LABEL: sil shared [transparent] [reabstraction_thunk] @_TTRXFo__iP__XFdCb__aPs9AnyObject__ : $@convention(c) @pseudogeneric (@inout_aliasable @block_storage @callee_owned () -> @out Any) -> @autoreleased AnyObject
+  // CHECK-LABEL: sil shared [transparent] [reabstraction_thunk] @_TTRXFo__iP__XFdCb__aPs9AnyObject__ : $@convention(c) (@inout_aliasable @block_storage @callee_owned () -> @out Any) -> @autoreleased AnyObject
   // CHECK:     bb0(%0 : $*@block_storage @callee_owned () -> @out Any):
   // CHECK-NEXT:  [[BLOCK_STORAGE_ADDR:%.*]] = project_block_storage %0
   // CHECK-NEXT:  [[FUNCTION:%.*]] = load [[BLOCK_STORAGE_ADDR]]

test/SILGen/objc_imported_generic.swift

@@ -77,7 +77,7 @@ public func genericBlockBridging<T: Ansible>(x: GenericClass<T>) {
 // CHECK-LABEL: sil @_TF21objc_imported_generic20genericBlockBridging
 // CHECK:         [[BLOCK_TO_FUNC:%.*]] = function_ref @_TTRGRxs9AnyObjectx21objc_imported_generic7AnsiblerXFdCb_dx_ax_XFo_ox_ox_
 // CHECK:         partial_apply [[BLOCK_TO_FUNC]]<T, {{.*}}>
-// CHECK:         [[FUNC_TO_BLOCK:%.*]] = function_ref @_TTRGRxs9AnyObjectx21objc_imported_generic7AnsiblerXFo_ox_ox_XFdCb_dx_ax_
+// CHECK:         [[FUNC_TO_BLOCK:%.*]] = function_ref @_TTRgRxs9AnyObjectx21objc_imported_generic7AnsiblerXFo_ox_ox_XFdCb_dx_ax_
 // CHECK:         init_block_storage_header {{.*}} invoke [[FUNC_TO_BLOCK]]<T,{{.*}}>
 
 // CHECK-LABEL: sil @_TF21objc_imported_generic20arraysOfGenericParam

test/SILGen/objc_thunks.swift

@@ -470,7 +470,7 @@ func registerAnsible() {
 
 // FIXME: would be nice if we didn't need to re-abstract as much here.
 
-// CHECK-LABEL: sil shared [transparent] [reabstraction_thunk] @_TTRXFo_oGSqFT_T____XFdCb_dGSqbT_T____ : $@convention(c) @pseudogeneric (@inout_aliasable @block_storage @callee_owned (@owned Optional<() -> ()>) -> (), Optional<@convention(block) () -> ()>) -> ()
+// CHECK-LABEL: sil shared [transparent] [reabstraction_thunk] @_TTRXFo_oGSqFT_T____XFdCb_dGSqbT_T____ : $@convention(c) (@inout_aliasable @block_storage @callee_owned (@owned Optional<() -> ()>) -> (), Optional<@convention(block) () -> ()>) -> ()
 // CHECK: [[HEAP_BLOCK_IUO:%.*]] = copy_block %1
 // CHECK: select_enum [[HEAP_BLOCK_IUO]]
 // CHECK: bb1: