SIL: allow casts to class-bound archetypes to be done as scalar-casts instead of address-casts

This allows such casts to be done in embedded swift.

rdar://156302495

lib/IRGen/GenCast.cpp

@@ -210,7 +210,8 @@ llvm::Value *irgen::emitClassDowncast(IRGenFunction &IGF, llvm::Value *from,
 
   // If the destination type is known to have a Swift-compatible
   // implementation, use the most specific entrypoint.
-  if (destClass && destClass->hasKnownSwiftImplementation()) {
+  if ((destClass && destClass->hasKnownSwiftImplementation()) ||
+      IGF.IGM.Context.LangOpts.hasFeature(Feature::Embedded)) {
     metadataRef = IGF.emitTypeMetadataRef(toType);
 
     switch (mode) {

lib/SIL/Utils/DynamicCasts.cpp

@@ -1378,23 +1378,26 @@ bool swift::canIRGenUseScalarCheckedCastInstructions(SILModule &M,
   // bridging, unless we can statically see that the source type inherits
   // NSError.
   
-  // A class-constrained archetype may be bound to NSError, unless it has a
-  // non-NSError superclass constraint. Casts to archetypes thus must always be
-  // indirect.
   if (auto archetype = targetFormalType->getAs<ArchetypeType>()) {
     // Only ever permit this if the source type is a reference type.
     if (!objectType.isAnyClassReferenceType())
       return false;
-    
-    auto super = archetype->getSuperclass();
-    if (super.isNull())
-      return false;
 
-    // A base class constraint that isn't NSError rules out the archetype being
-    // bound to NSError.
     if (M.getASTContext().LangOpts.EnableObjCInterop) {
+      // A class-constrained archetype may be bound to NSError, unless it has a
+      // non-NSError superclass constraint. Casts to archetypes thus must always be
+      // indirect.
+      auto super = archetype->getSuperclass();
+      if (super.isNull())
+        return false;
+
+      // A base class constraint that isn't NSError rules out the archetype being
+      // bound to NSError.
       if (auto nserror = M.Types.getNSErrorType())
          return !super->isEqual(nserror);
+    } else {
+      if (!archetype->requiresClass())
+        return false;
     }
     
     // If NSError wasn't loaded, any base class constraint must not be NSError.

test/IRGen/dynamic_self_cast.swift

@@ -35,7 +35,7 @@ public class SelfCasts {
   }
 
   // CHECK-LABEL: define {{(dllexport )?}}{{(protected )?}}swiftcc ptr @"$s17dynamic_self_cast9SelfCastsC016classGenericFromD0xyRlzClFZ"(ptr %T, ptr swiftself %0)
-  // CHECK: call zeroext i1 @swift_dynamicCast(ptr {{%.*}}, ptr {{%.*}}, ptr %0, ptr %T, {{.*}})
+  // CHECK: call ptr @swift_dynamicCastUnknownClassUnconditional(ptr {{%.*}}, ptr %T, ptr null, i32 0, i32 0) #4
   // CHECK: ret
   public static func classGenericFromSelf<T : AnyObject>() -> T {
     let s = Self()
@@ -72,7 +72,7 @@ public class SelfCasts {
   }
 
   // CHECK-LABEL: define {{(dllexport )?}}{{(protected )?}}swiftcc {{i32|i64}} @"$s17dynamic_self_cast9SelfCastsC016classGenericFromD11ConditionalxSgyRlzClFZ"(ptr %T, ptr swiftself %0)
-  // CHECK: call zeroext i1 @swift_dynamicCast(ptr {{%.*}}, ptr {{%.*}}, ptr %0, ptr %T, {{.*}})
+  // CHECK: call ptr @swift_dynamicCastUnknownClass(ptr {{%.*}}, ptr %T)
   // CHECK: ret
   public static func classGenericFromSelfConditional<T : AnyObject>() -> T? {
     let s = Self()

test/SILGen/dynamic_self_cast.swift

@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend -Xllvm -sil-print-types -emit-silgen %s | %FileCheck %s
+// RUN: %target-swift-frontend -Xllvm -sil-print-types -disable-objc-interop -emit-silgen %s | %FileCheck %s
 
 public class SelfCasts {
   // CHECK-LABEL: sil [ossa] @$s17dynamic_self_cast9SelfCastsC02toD0yACXDACFZ : $@convention(method) (@guaranteed SelfCasts, @thick SelfCasts.Type) -> @owned SelfCasts {
@@ -31,7 +31,7 @@ public class SelfCasts {
   }
 
   // CHECK-LABEL: sil [ossa] @$s17dynamic_self_cast9SelfCastsC016classGenericFromD0xyRlzClFZ : $@convention(method) <T where T : AnyObject> (@thick SelfCasts.Type) -> @owned T
-  // CHECK: unconditional_checked_cast_addr @dynamic_self SelfCasts in {{.*}} : $*SelfCasts to T in {{.*}} : $*T
+  // CHECK: unconditional_checked_cast {{.*}} : $SelfCasts to T
   // CHECK: }
   public static func classGenericFromSelf<T : AnyObject>() -> T {
     let s = Self()
@@ -68,7 +68,7 @@ public class SelfCasts {
   }
 
   // CHECK-LABEL: sil [ossa] @$s17dynamic_self_cast9SelfCastsC016classGenericFromD11ConditionalxSgyRlzClFZ : $@convention(method) <T where T : AnyObject> (@thick SelfCasts.Type) -> @owned Optional<T> {
-  // CHECK: checked_cast_addr_br take_always @dynamic_self SelfCasts in {{.*}} : $*SelfCasts to T in {{.*}} : $*T
+  // CHECK: checked_cast_br @dynamic_self SelfCasts in {{.*}} : $SelfCasts to T
   // CHECK: }
   public static func classGenericFromSelfConditional<T : AnyObject>() -> T? {
     let s = Self()

test/SILGen/dynamic_self_cast_objc.swift

@@ -0,0 +1,82 @@
+// RUN: %target-swift-frontend -Xllvm -sil-print-types -module-name=dynamic_self_cast -emit-silgen %s | %FileCheck %s
+
+// REQUIRES: objc_interop
+
+public class SelfCasts {
+  // CHECK-LABEL: sil [ossa] @$s17dynamic_self_cast9SelfCastsC02toD0yACXDACFZ : $@convention(method) (@guaranteed SelfCasts, @thick SelfCasts.Type) -> @owned SelfCasts {
+  // CHECK: unconditional_checked_cast {{.*}} : $SelfCasts to @dynamic_self SelfCasts
+  // CHECK: }
+  public static func toSelf(_ s: SelfCasts) -> Self {
+    return s as! Self
+  }
+
+  // CHECK-LABEL: sil [ossa] @$s17dynamic_self_cast9SelfCastsC09genericToD0yACXDxlFZ : $@convention(method) <T> (@in_guaranteed T, @thick SelfCasts.Type) -> @owned SelfCasts {
+  // CHECK: unconditional_checked_cast_addr T in {{.*}} : $*T to @dynamic_self SelfCasts in {{.*}} : $*SelfCasts
+  // CHECK: }
+  public static func genericToSelf<T>(_ s: T) -> Self {
+    return s as! Self
+  }
+
+  // CHECK-LABEL: sil [ossa] @$s17dynamic_self_cast9SelfCastsC014classGenericToD0yACXDxRlzClFZ : $@convention(method) <T where T : AnyObject> (@guaranteed T, @thick SelfCasts.Type) -> @owned SelfCasts {
+  // CHECK: unconditional_checked_cast {{.*}} : $T to @dynamic_self SelfCasts
+  // CHECK: }
+  public static func classGenericToSelf<T : AnyObject>(_ s: T) -> Self {
+    return s as! Self
+  }
+
+  // CHECK-LABEL: sil [ossa] @$s17dynamic_self_cast9SelfCastsC011genericFromD0xylFZ : $@convention(method) <T> (@thick SelfCasts.Type) -> @out T {
+  // CHECK: unconditional_checked_cast_addr @dynamic_self SelfCasts in {{.*}} : $*SelfCasts to T in {{.*}} : $*T
+  // CHECK: }
+  public static func genericFromSelf<T>() -> T {
+    let s = Self()
+    return s as! T
+  }
+
+  // CHECK-LABEL: sil [ossa] @$s17dynamic_self_cast9SelfCastsC016classGenericFromD0xyRlzClFZ : $@convention(method) <T where T : AnyObject> (@thick SelfCasts.Type) -> @owned T
+  // CHECK: unconditional_checked_cast_addr @dynamic_self SelfCasts in {{.*}} : $*SelfCasts to T in {{.*}} : $*T
+  // CHECK: }
+  public static func classGenericFromSelf<T : AnyObject>() -> T {
+    let s = Self()
+    return s as! T
+  }
+
+  // CHECK-LABEL: sil [ossa] @$s17dynamic_self_cast9SelfCastsC02toD11ConditionalyACXDSgACFZ : $@convention(method) (@guaranteed SelfCasts, @thick SelfCasts.Type) -> @owned Optional<SelfCasts> {
+  // CHECK: checked_cast_br SelfCasts in {{.*}} : $SelfCasts to @dynamic_self SelfCasts
+  // CHECK: }
+  public static func toSelfConditional(_ s: SelfCasts) -> Self? {
+    return s as? Self
+  }
+
+  // CHECK-LABEL: sil [ossa] @$s17dynamic_self_cast9SelfCastsC09genericToD11ConditionalyACXDSgxlFZ : $@convention(method) <T> (@in_guaranteed T, @thick SelfCasts.Type) -> @owned Optional<SelfCasts> {
+  // CHECK: checked_cast_addr_br take_always T in {{.*}} : $*T to @dynamic_self SelfCasts in {{.*}} : $*SelfCasts
+  // CHECK: }
+  public static func genericToSelfConditional<T>(_ s: T) -> Self? {
+    return s as? Self
+  }
+
+  // CHECK-LABEL: sil [ossa] @$s17dynamic_self_cast9SelfCastsC014classGenericToD11ConditionalyACXDSgxRlzClFZ : $@convention(method) <T where T : AnyObject> (@guaranteed T, @thick SelfCasts.Type) -> @owned Optional<SelfCasts> {
+  // CHECK: checked_cast_br T in {{.*}} : $T to @dynamic_self SelfCasts
+  // CHECK: }
+  public static func classGenericToSelfConditional<T : AnyObject>(_ s: T) -> Self? {
+    return s as? Self
+  }
+
+  // CHECK-LABEL: sil [ossa] @$s17dynamic_self_cast9SelfCastsC011genericFromD11ConditionalxSgylFZ : $@convention(method) <T> (@thick SelfCasts.Type) -> @out Optional<T> {
+  // CHECK: checked_cast_addr_br take_always @dynamic_self SelfCasts in {{.*}} : $*SelfCasts to T in {{.*}} : $*T
+  // CHECK: }
+  public static func genericFromSelfConditional<T>() -> T? {
+    let s = Self()
+    return s as? T
+  }
+
+  // CHECK-LABEL: sil [ossa] @$s17dynamic_self_cast9SelfCastsC016classGenericFromD11ConditionalxSgyRlzClFZ : $@convention(method) <T where T : AnyObject> (@thick SelfCasts.Type) -> @owned Optional<T> {
+  // CHECK: checked_cast_addr_br take_always @dynamic_self SelfCasts in {{.*}} : $*SelfCasts to T in {{.*}} : $*T
+  // CHECK: }
+  public static func classGenericFromSelfConditional<T : AnyObject>() -> T? {
+    let s = Self()
+    return s as? T
+  }
+
+  public required init() {}
+}
+

test/SILGen/generic_casts.swift

@@ -1,5 +1,5 @@
 
-// RUN: %target-swift-emit-silgen -Xllvm -sil-print-types -swift-version 5 -module-name generic_casts -Xllvm -sil-full-demangle %s | %FileCheck %s
+// RUN: %target-swift-emit-silgen -Xllvm -sil-print-types -disable-objc-interop -swift-version 5 -module-name generic_casts -Xllvm -sil-full-demangle %s | %FileCheck %s
 
 protocol ClassBound : class {}
 protocol NotClassBound {}
@@ -59,8 +59,7 @@ func class_archetype_to_class_archetype
 <T:ClassBound, U:ClassBound>(_ t:T) -> U {
   return t as! U
   // Error bridging can change the identity of class-constrained archetypes.
-  // CHECK: unconditional_checked_cast_addr T in {{%.*}} : $*T to U in [[DOWNCAST_ADDR:%.*]] : $*U
-  // CHECK: [[DOWNCAST:%.*]] = load [take] [[DOWNCAST_ADDR]]
+  // CHECK: [[DOWNCAST:%.*]] = unconditional_checked_cast {{%.*}} : $T to U
   // CHECK: return [[DOWNCAST]] : $U
 }
 
@@ -69,7 +68,7 @@ func class_archetype_is_class_archetype
 <T:ClassBound, U:ClassBound>(_ t:T, u:U.Type) -> Bool {
   return t is U
   // Error bridging can change the identity of class-constrained archetypes.
-  // CHECK: checked_cast_addr_br {{.*}} T in {{%.*}} : $*T to U in {{%.*}} : $*U
+  // CHECK: checked_cast_br T in {{%.*}} : $T to U
 }
 
 // CHECK-LABEL: sil hidden [ossa] @$s13generic_casts38opaque_archetype_to_addr_only_concrete{{[_0-9a-zA-Z]*}}F
@@ -158,8 +157,7 @@ func opaque_existential_is_class_archetype
 func class_existential_to_class_archetype
 <T:ClassBound>(_ p:ClassBound) -> T {
   return p as! T
-  // CHECK: unconditional_checked_cast_addr any ClassBound in {{%.*}} : $*any ClassBound to T in [[DOWNCAST_ADDR:%.*]] : $*T
-  // CHECK: [[DOWNCAST:%.*]] = load [take] [[DOWNCAST_ADDR]]
+  // CHECK: [[DOWNCAST:%.*]] = unconditional_checked_cast {{%.*}} : $any ClassBound to T
   // CHECK: return [[DOWNCAST]] : $T
 }
 
@@ -167,7 +165,7 @@ func class_existential_to_class_archetype
 func class_existential_is_class_archetype
 <T:ClassBound>(_ p:ClassBound, _: T) -> Bool {
   return p is T
-  // CHECK: checked_cast_addr_br {{.*}} any ClassBound in {{%.*}} : $*any ClassBound to T in {{%.*}} : $*T
+  // CHECK: checked_cast_br any ClassBound in {{%.*}} : $any ClassBound to T
 }
 
 // CHECK-LABEL: sil hidden [ossa] @$s13generic_casts40opaque_existential_to_addr_only_concrete{{[_0-9a-zA-Z]*}}F

test/SILOptimizer/assemblyvision_remark/cast_remarks.swift

@@ -2,6 +2,7 @@
 
 // REQUIRES: optimized_stdlib
 // REQUIRES: swift_stdlib_no_asserts
+// REQUIRES: OS=macosx
 
 ///////////////////
 // Generic Casts //

test/SILOptimizer/rcidentity_opaque.sil

@@ -1,4 +1,4 @@
-// RUN: %target-sil-opt -rc-id-dumper -enable-sil-opaque-values -module-name Swift %s -o /dev/null | %FileCheck %s
+// RUN: %target-sil-opt -rc-id-dumper -enable-sil-opaque-values -disable-objc-interop -module-name Swift %s -o /dev/null | %FileCheck %s
 
 import Builtin
 
@@ -295,7 +295,7 @@ bb0(%0 : @owned $T):
 //
 // CHECK-LABEL: @testClassToClassArchetypeIsBridged
 // CHECK: RESULT #0: 0 = 0
-// CHECK: RESULT #1: 1 = 1
+// CHECK: RESULT #1: 1 = 0
 sil [ossa] @testClassToClassArchetypeIsBridged : $@convention(thin) <U : AnyObject>(@owned Base) -> @owned U {
 bb0(%0 : @owned $Base):
   %1 = unconditional_checked_cast %0 : $Base to U

test/embedded/existential-class-bound1.swift

@@ -10,6 +10,7 @@
 protocol ClassBound: AnyObject {
     func foo()
     func bar()
+    func predicate() -> Bool
 }
 
 class MyClass {}
@@ -230,6 +231,22 @@ func testP4() -> any P4 {
   return C4(t: K4(x: 437))
 }
 
+var gg: any ClassBound = MyClass()
+
+extension ClassBound {
+  public func isSame(_ rhs: some ClassBound) -> Bool {
+    if let rhs = rhs as? Self {
+      return rhs.predicate()
+    }
+    return false 
+  }
+  public func predicate() -> Bool { true }
+}
+
+@inline(never)
+func testIsSame(_ p: any ClassBound) -> Bool {
+  return p.isSame(gg)
+}
 
 
 @main
@@ -261,6 +278,11 @@ struct Main {
         // CHECK: 102
         testP4().foo()
         // CHECK: 437
+
+        print(testIsSame(MyClass()))
+        // CHECK: true
+        print(testIsSame(MyOtherClass()))
+        // CHECK: false
     }
 }