[transfer-non-sendable] Teach SILIsolationInfo how to handle "look through instructions" when finding actor instances.

From the perspective of the IR, we are changing SILIsolationInfo such that
inferring an actor instance means looking at equivalence classes of values where
we consider operands to look through instructions to be equivalent to their dest
value. The result is that cases where the IR maybe puts in a copy_value or the
like, we consider the copy_value to have the same isolation info as using the
actor directly. This prevents a class of crashes due to merge failings. Example:

```swift
actor MyActor {
  init() async {

  init(ns: NonSendableKlass) async {
    self.k = NonSendableKlass()
    self.helper(ns)
  }

  func helper(_ newK: NonSendableKlass) {}
}
```

Incidently, we already had a failing test case from this behavior rather than
the one that was the original genesis. Specifically:

1. If a function's SILIsolationInfo is the same as the isolation info of a
SILValue, we assume that no transfer actually occurs.

2. Since we were taking too static of a view of actor instances when comparing,
we would think that a SILIsolationInfo of a #isolation parameter to as an
argument would be different than the ambient's function isolation which is also
that same one. So we would emit a transfer non transferrable error if we pass in
any parameters of the ambient function into another isolated function. Example:

```swift
actor Test {

  @TaskLocal static var local: Int?

  func withTaskLocal(isolation: isolated (any Actor)? = #isolation,
                     _ body: (consuming NonSendableValue, isolated (any Actor)?) -> Void) async {
    Self.$local.withValue(12) {

      // We used to get these errors here since we thought that body's isolation
      // was different than the body's isolation.
      //
      //  warning: sending 'body' risks causing data races
      //  note: actor-isolated 'body' is captured by a actor-isolated closure...
      body(NonSendableValue(), isolation)
    }
  }
}
```

rdar://129400019
(cherry picked from commit c01f551)

Author: gottesmm

include/swift/SILOptimizer/Utils/SILIsolationInfo.h

@@ -55,10 +55,16 @@ class ActorInstance {
   ActorInstance(SILValue value, Kind kind)
       : value(value, std::underlying_type<Kind>::type(kind)) {}
 
+  /// We want to look through certain instructions like end_init_ref that have
+  /// the appropriate actor type but could disguise the actual underlying value
+  /// that we want to represent our actor.
+  static SILValue lookThroughInsts(SILValue value);
+
 public:
   ActorInstance() : ActorInstance(SILValue(), Kind::Value) {}
 
   static ActorInstance getForValue(SILValue value) {
+    value = lookThroughInsts(value);
     return ActorInstance(value, Kind::Value);
   }
 
@@ -411,6 +417,10 @@ class SILDynamicMergedIsolationInfo {
   void printForDiagnostics(llvm::raw_ostream &os) const {
     innerInfo.printForDiagnostics(os);
   }
+
+  SWIFT_DEBUG_DUMPER(dumpForDiagnostics()) {
+    innerInfo.dumpForDiagnostics();
+  }
 };
 
 } // namespace swift

lib/SILOptimizer/Utils/SILIsolationInfo.cpp

@@ -393,6 +393,7 @@ SILIsolationInfo SILIsolationInfo::get(SILInstruction *inst) {
         // TODO: We really should be doing this based off of an Operand. Then
         // we would get the SILValue() for the first element. Today this can
         // only mess up isolation history.
+
         return SILIsolationInfo::getActorInstanceIsolated(
             SILValue(), isolatedOp->get(), nomDecl);
       }
@@ -1099,6 +1100,30 @@ bool SILIsolationInfo::isNonSendableType(SILType type, SILFunction *fn) {
   return !type.isSendable(fn);
 }
 
+//===----------------------------------------------------------------------===//
+//                            MARK: ActorInstance
+//===----------------------------------------------------------------------===//
+
+SILValue ActorInstance::lookThroughInsts(SILValue value) {
+  if (!value)
+    return value;
+
+  while (auto *svi = dyn_cast<SingleValueInstruction>(value)) {
+    if (isa<EndInitLetRefInst>(svi) || isa<CopyValueInst>(svi) ||
+        isa<MoveValueInst>(svi) || isa<ExplicitCopyValueInst>(svi) ||
+        isa<BeginBorrowInst>(svi) ||
+        isa<CopyableToMoveOnlyWrapperValueInst>(svi) ||
+        isa<MoveOnlyWrapperToCopyableValueInst>(svi)) {
+      value = lookThroughInsts(svi->getOperand(0));
+      continue;
+    }
+
+    break;
+  }
+
+  return value;
+}
+
 //===----------------------------------------------------------------------===//
 //                    MARK: SILDynamicMergedIsolationInfo
 //===----------------------------------------------------------------------===//

test/Concurrency/async_task_locals_basic_warnings_bug_isolation.swift

@@ -2,14 +2,10 @@
 // RUN: %target-swift-frontend -plugin-path %swift-plugin-dir -emit-module -emit-module-path %t/OtherActors.swiftmodule -module-name OtherActors %S/Inputs/OtherActors.swift -disable-availability-checking
 
 // RUN: %target-swift-frontend -I %t -plugin-path %swift-plugin-dir -disable-availability-checking -strict-concurrency=complete -parse-as-library %s -emit-sil -o /dev/null -verify
-// RUN: %target-swift-frontend -I %t -plugin-path %swift-plugin-dir -disable-availability-checking -strict-concurrency=complete -parse-as-library %s -emit-sil -o /dev/null -verify -enable-upcoming-feature RegionBasedIsolation
 
 // REQUIRES: concurrency
 // REQUIRES: asserts
 
-// FIXME: rdar://125078448 is resolved
-// XFAIL: *
-
 actor Test {
 
   @TaskLocal static var local: Int?

test/Concurrency/silisolationinfo_inference.sil

@@ -32,6 +32,7 @@ sil @constructNonSendableKlassIndirect : $@convention(thin) () -> @out NonSendab
 sil @constructNonSendableKlassIndirectAsync : $@convention(thin) @async () -> @out NonSendableKlass
 sil @useUnmanagedNonSendableKlass : $@convention(thin) (@guaranteed @sil_unmanaged NonSendableKlass) -> ()
 
+sil @useActor : $@convention(thin) (@sil_isolated @guaranteed MyActor) -> @owned NonSendableKlass
 
 ///////////////////////
 // MARK: Basic Tests //
@@ -699,3 +700,24 @@ bb7:
   %9999 = tuple ()
   return %9999 : $()
 }
+
+// CHECK-LABEL: begin running test 1 of 1 on lookthrough_test: sil-isolation-info-inference with: @trace[0]
+// CHECK-NEXT: Input Value:   %7 = apply %6(%5) : $@convention(thin) (@sil_isolated @guaranteed MyActor) -> @owned NonSendableKlass
+// CHECK-NEXT: Isolation: 'argument'-isolated
+// CHECK-NEXT: end running test 1 of 1 on lookthrough_test: sil-isolation-info-inference with: @trace[0]
+sil [ossa] @lookthrough_test : $@convention(thin) (@owned MyActor) -> @owned NonSendableKlass {
+bb0(%0 : @owned $MyActor):
+  specify_test "sil-isolation-info-inference @trace[0]"
+  debug_value %0 : $MyActor, let, name "argument"
+  %1 = end_init_let_ref %0 : $MyActor
+  %1a = copy_value %1 : $MyActor
+  %1b = move_value %1a : $MyActor
+  %1c = begin_borrow %1b : $MyActor
+  %2 = function_ref @useActor : $@convention(thin) (@sil_isolated @guaranteed MyActor) -> @owned NonSendableKlass
+  %3 = apply %2(%1c) : $@convention(thin) (@sil_isolated @guaranteed MyActor) -> @owned NonSendableKlass
+  debug_value [trace] %3 : $NonSendableKlass
+  end_borrow %1c : $MyActor
+  destroy_value %1 : $MyActor
+  destroy_value %1b : $MyActor
+  return %3 : $NonSendableKlass
+}

test/Concurrency/transfernonsendable_initializers.swift

@@ -50,7 +50,13 @@ actor ActorWithSynchronousNonIsolatedInit {
     }
   }
 
+  init(ns: NonSendableKlass) async {
+    self.k = NonSendableKlass()
+    self.isolatedHelper(ns)
+  }
+
   nonisolated func helper(_ newK: NonSendableKlass) {}
+  func isolatedHelper(_ newK: NonSendableKlass) {}
 }
 
 func initActorWithSyncNonIsolatedInit() {

test/Concurrency/transfernonsendable_ownership.swift

@@ -105,3 +105,19 @@ func testInOutError(_ x: inout Klass) async {
   // expected-note @-1 {{sending global actor 'CustomActor'-isolated 'x' to main actor-isolated global function 'transferToMain'}}
   _ = consume x // expected-note {{consumed here}}
 } // expected-note {{used here}}
+
+actor ActorTestCase {
+  let k = Klass()
+
+  // TODO: This crashes the compiler since we attempt to hop_to_executor to the
+  // value that is materialized onto disk.
+  //
+  // consuming func test() async {
+  //   await transferToMain(k)
+  // }
+
+  borrowing func test2() async {
+    await transferToMain(k) // expected-warning {{sending 'self.k' risks causing data races}}
+    // expected-note @-1 {{sending 'self'-isolated 'self.k' to main actor-isolated global function 'transferToMain' risks causing data races between main actor-isolated and 'self'-isolated uses}}
+  }
+}