Merge pull request #12677 from graydon/rdar-34913689-dead-function-elim-vs-foreign-declref-keypaths-swift-4.1-branch

Author: swift-ci

lib/SILOptimizer/IPO/DeadFunctionElimination.cpp

@@ -223,15 +223,22 @@ class FunctionLivenessComputation {
         auto id = component.getComputedPropertyId();
         switch (id.getKind()) {
         case KeyPathPatternComponent::ComputedPropertyId::DeclRef: {
-          auto decl = cast<AbstractFunctionDecl>(id.getDeclRef().getDecl());
-          if (auto clas = dyn_cast<ClassDecl>(decl->getDeclContext())) {
-            ensureAliveClassMethod(getMethodInfo(decl, /*witness*/ false),
-                                   dyn_cast<FuncDecl>(decl),
-                                   clas);
-          } else if (isa<ProtocolDecl>(decl->getDeclContext())) {
-            ensureAliveProtocolMethod(getMethodInfo(decl, /*witness*/ true));
+          auto declRef = id.getDeclRef();
+          if (declRef.isForeign) {
+            // Nothing to do here: foreign functions aren't ours to be deleting.
+            // (And even if they were, they're ObjC-dispatched and thus anchored
+            // already: see isAnchorFunction)
           } else {
-            llvm_unreachable("key path keyed by a non-class, non-protocol method");
+            auto decl = cast<AbstractFunctionDecl>(declRef.getDecl());
+            if (auto clas = dyn_cast<ClassDecl>(decl->getDeclContext())) {
+              ensureAliveClassMethod(getMethodInfo(decl, /*witness*/ false),
+                                     dyn_cast<FuncDecl>(decl),
+                                     clas);
+            } else if (isa<ProtocolDecl>(decl->getDeclContext())) {
+              ensureAliveProtocolMethod(getMethodInfo(decl, /*witness*/ true));
+            } else {
+              llvm_unreachable("key path keyed by a non-class, non-protocol method");
+            }
           }
           break;
         }

test/SILOptimizer/Inputs/keypaths_objc.h

@@ -0,0 +1,14 @@
+@import Foundation;
+
+@interface ObjCFoo
+
+@property(readonly) NSString *_Nonnull objcProp;
+
+@end
+
+
+@interface ObjCFoo (Extras)
+
+@property(readonly) NSString *_Nonnull objcExtraProp;
+
+@end

test/SILOptimizer/dead_func_objc_extension_keypath.swift

@@ -0,0 +1,7 @@
+// RUN: %target-swift-frontend %s -O -emit-sil -import-objc-header %S/Inputs/keypaths_objc.h
+// REQUIRES: objc_interop
+
+import Foundation
+public func test_nocrash_rdar34913689() {
+  _ = \ObjCFoo.objcExtraProp
+}