Merge pull request #71808 from eeckstein/global_async_function_pointers

Support statically initialized global async function pointers

Author: eeckstein

SwiftCompilerSources/Sources/SIL/GlobalVariable.swift

@@ -137,9 +137,6 @@ extension Instruction {
         // initializers.
         return false
       }
-    case let fri as FunctionRefInst:
-      // TODO: support async function pointers in static globals.
-      return !fri.referencedFunction.isAsync
     case is StructInst,
          is TupleInst,
          is EnumInst,
@@ -152,7 +149,8 @@ extension Instruction {
          is ConvertFunctionInst,
          is ThinToThickFunctionInst,
          is AddressToPointerInst,
-         is GlobalAddrInst:
+         is GlobalAddrInst,
+         is FunctionRefInst:
       return true
     default:
       return false

lib/IRGen/GenConstant.cpp

@@ -378,9 +378,13 @@ Explosion irgen::emitConstantValue(IRGenModule &IGM, SILValue operand,
     SILFunction *fn = FRI->getReferencedFunction();
 
     llvm::Constant *fnPtr = IGM.getAddrOfSILFunction(fn, NotForDefinition);
-    assert(!fn->isAsync() && "TODO: support async functions");
-
     CanSILFunctionType fnType = FRI->getType().getAs<SILFunctionType>();
+
+    if (irgen::classifyFunctionPointerKind(fn).isAsyncFunctionPointer()) {
+      llvm::Constant *asyncFnPtr = IGM.getAddrOfAsyncFunctionPointer(fn);
+      fnPtr = llvm::ConstantExpr::getBitCast(asyncFnPtr, fnPtr->getType());
+    }
+
     auto authInfo = PointerAuthInfo::forFunctionPointer(IGM, fnType);
     if (authInfo.isSigned()) {
       auto constantDiscriminator =

test/Concurrency/global_function_pointer.swift

@@ -0,0 +1,46 @@
+// RUN: %target-swift-frontend -enable-experimental-feature SymbolLinkageMarkers -emit-sil -disable-availability-checking -parse-as-library %s | %FileCheck %s --check-prefix=CHECK-SIL
+// RUN: %target-build-swift -enable-experimental-feature SymbolLinkageMarkers -Xfrontend -disable-availability-checking -Xfrontend -parse-as-library %s -o %t_binary
+// RUN: %target-codesign %t_binary
+// RUN: %target-run %t_binary | %FileCheck %s --check-prefix=CHECK-EXEC
+
+// REQUIRES: concurrency
+// REQUIRES: executable_test
+// REQUIRES: OS=macosx || OS=ios
+// REQUIRES: swift_in_compiler
+
+// rdar://76038845
+// REQUIRES: concurrency_runtime
+// UNSUPPORTED: back_deployment_runtime
+
+@MainActor
+var foo: Int = 42
+
+func asyncFunc() async {
+  print("Hello World!")
+}
+
+public func callAsync() async {
+  await asyncFunc()
+}
+
+// CHECK-SIL-LABEL: sil_global @$s23global_function_pointer5gfptryyYacvp : $@async @callee_guaranteed () -> () = {
+// CHECK-SIL:         %0 = function_ref @$s23global_function_pointer9callAsyncyyYaF : $@convention(thin) @async () -> ()
+// CHECK-SIL-NEXT:    %initval = thin_to_thick_function %0 : $@convention(thin) @async () -> () to $@async @callee_guaranteed () -> ()
+// CHECK-SIL-NEXT:  }
+
+@_section("__DATA,__mysection")
+public var gfptr = callAsync
+
+@main struct MyProgram {
+  static func main() async throws {
+    print("\(foo)")
+    foo += 1
+    await gfptr()
+    print("\(foo)")
+  }
+}
+
+// CHECK-EXEC: 42
+// CHECK-EXEC-NEXT: Hello World!
+// CHECK-EXEC-NEXT: 43
+