Simplify lifetime extension for async ObjC calls.

Since the clean-up is not unwind only, we can rely on the
clean-ups to be emitted on both result and throw paths.

This does slightly change when the hop_to_executor is emitted,
in those paths, but that shouldn't matter.

refactors solution for rdar://78982371

Author: kavon

lib/SILGen/ManagedValue.cpp

@@ -58,20 +58,20 @@ ManagedValue ManagedValue::copy(SILGenFunction &SGF, SILLocation loc) const {
 
 // Emit an unmanaged copy of this value
 // WARNING: Callers of this API should manage the cleanup of this value!
-ManagedValue ManagedValue::unmanagedCopy(SILGenFunction &SGF,
+SILValue ManagedValue::unmanagedCopy(SILGenFunction &SGF,
                                          SILLocation loc) const {
   auto &lowering = SGF.getTypeLowering(getType());
   if (lowering.isTrivial())
-    return *this;
+    return getValue();
 
   if (getType().isObject()) {
     auto copy = SGF.B.emitCopyValueOperation(loc, getValue());
-    return ManagedValue::forUnmanaged(copy);
+    return copy;
   }
 
   SILValue buf = SGF.emitTemporaryAllocation(loc, getType());
   SGF.B.createCopyAddr(loc, getValue(), buf, IsNotTake, IsInitialization);
-  return ManagedValue::forUnmanaged(buf);
+  return buf;
 }
 
 /// Emit a copy of this value with independent ownership.

lib/SILGen/ManagedValue.h

@@ -280,7 +280,7 @@ class ManagedValue {
 
   /// Returns an unmanaged copy of this value.
   /// WARNING: Callers of this API should manage the cleanup of this value!
-  ManagedValue unmanagedCopy(SILGenFunction &SGF, SILLocation loc) const;
+  SILValue unmanagedCopy(SILGenFunction &SGF, SILLocation loc) const;
 
   /// Emit a copy of this value with independent ownership into the current
   /// formal evaluation scope.

lib/SILGen/SILGenApply.cpp

@@ -4573,7 +4573,7 @@ RValue SILGenFunction::emitApply(
   // generates `await_async_continuation`.
   // Lifetime is extended by creating unmanaged copies here and by pushing the
   // cleanups required just before the result plan is generated.
-  SmallVector<ManagedValue, 8> unmanagedCopies;
+  SmallVector<SILValue, 8> unmanagedCopies;
   if (calleeTypeInfo.foreign.async) {
     for (auto arg : args) {
       if (arg.hasCleanup()) {
@@ -4660,29 +4660,22 @@ RValue SILGenFunction::emitApply(
                               *foreignError, calleeTypeInfo.foreign.async);
   }
 
-  // For objc async calls, push cleanup to be used on throw paths in the result
-  // planner.
-  for (unsigned i : indices(unmanagedCopies)) {
-    SILValue value = unmanagedCopies[i].getValue();
-    Cleanups.pushCleanup<FixLifetimeDestroyCleanup>(value);
-    unmanagedCopies[i] = ManagedValue(value, Cleanups.getTopCleanup());
+  // For objc async calls, push cleanup to be used on
+  // both result and throw paths prior to finishing the result plan.
+  if (calleeTypeInfo.foreign.async) {
+    for (auto unmanagedCopy : unmanagedCopies) {
+      Cleanups.pushCleanup<FixLifetimeDestroyCleanup>(unmanagedCopy);
+    }
+  } else {
+    assert(unmanagedCopies.empty());
   }
 
   auto directResultsArray = makeArrayRef(directResults);
   RValue result = resultPlan->finish(*this, loc, substResultType,
                                      directResultsArray, bridgedForeignError);
   assert(directResultsArray.empty() && "didn't claim all direct results");
 
-  // For objc async calls, generate cleanup on the resume path here and forward
-  // the previously pushed cleanups.
   if (calleeTypeInfo.foreign.async) {
-    for (auto unmanagedCopy : unmanagedCopies) {
-      auto value = unmanagedCopy.forward(*this);
-      B.emitFixLifetime(loc, value);
-      B.emitDestroyOperation(loc, value);
-    }
-
-    // hop back to the current executor
     breadcrumb.emit(*this, loc);
   }
 

test/SILGen/objc_async.swift

@@ -195,9 +195,9 @@ func testSlowServerFromMain(slowServer: SlowServer) async throws {
   // CHECK: await_async_continuation [[CONT]] {{.*}}, resume [[RESUME:bb[0-9]+]]
   // CHECK: [[RESUME]]:
   // CHECK: [[RESULT:%.*]] = load [trivial] [[RESUME_BUF]]
+  // CHECK: hop_to_executor %6 : $MainActor
   // CHECK: fix_lifetime [[COPY]]
   // CHECK: destroy_value [[COPY]]
-  // CHECK: hop_to_executor %6 : $MainActor
   // CHECK: dealloc_stack [[RESUME_BUF]]
   let _: Int = await slowServer.doSomethingSlow("mail")
 }