Mangling: add a specialization mangling for changing the function type representation of a function

Author: eeckstein

docs/ABI/Mangling.rst

@@ -1350,7 +1350,7 @@ Some kinds need arguments, which precede ``Tf``.
   spec-arg ::= identifier
   spec-arg ::= type
 
-  SPEC-INFO ::= FRAGILE? ASYNC-REMOVED? PASSID
+  SPEC-INFO ::= FRAGILE? (ASYNC-REMOVED|REPR-CHANGED)? PASSID
 
   PASSID ::= '0'                             // AllocBoxToStack,
   PASSID ::= '1'                             // ClosureSpecializer,
@@ -1361,10 +1361,12 @@ Some kinds need arguments, which precede ``Tf``.
   PASSID ::= '6'                             // MoveDiagnosticInOutToOut,
   PASSID ::= '7'                             // AsyncDemotion,
   PASSID ::= '8'                             // PackSpecialization,
+  PASSID ::= '9'                             // EmbeddedWitnessCallSpecialization
 
   FRAGILE ::= 'q'
 
   ASYNC-REMOVED ::= 'a'                      // async effect removed
+  REPR-CHANGED ::= 'r'                       // function type representation changed
 
   ARG-SPEC-KIND ::= 'n'                      // Unmodified argument
   ARG-SPEC-KIND ::= 'c'                      // Consumes n 'type' arguments which are closed over types in argument order

include/swift/Demangling/Demangle.h

@@ -165,7 +165,8 @@ enum class SpecializationPass : uint8_t {
   MoveDiagnosticInOutToOut,
   AsyncDemotion,
   PackSpecialization,
-  LAST = PackSpecialization
+  EmbeddedWitnessCallSpecialization,
+  LAST = EmbeddedWitnessCallSpecialization
 };
 
 constexpr uint8_t MAX_SPECIALIZATION_PASS = 10;

include/swift/Demangling/DemangleNodes.def

@@ -399,6 +399,8 @@ NODE(OutlinedEnumProjectDataForLoad)
 NODE(OutlinedEnumGetTag)
 // Added in Swift 5.9 + 1
 NODE(AsyncRemoved)
+// Added in Swift 6.3 + 1
+NODE(RepresentationChanged)
 
 // Added in Swift 5.TBD
 NODE(ObjectiveCProtocolSymbolicReference)

lib/Demangling/Demangler.cpp

@@ -3377,6 +3377,8 @@ NodePointer Demangler::demangleGenericSpecializationWithDroppedArguments() {
 NodePointer Demangler::demangleFunctionSpecialization() {
   NodePointer Spec = demangleSpecAttributes(
         Node::Kind::FunctionSignatureSpecialization);
+  if (Spec && Spec->getFirstChild()->getKind() == Node::Kind::RepresentationChanged)
+    return Spec;
   while (Spec && !nextIf('_')) {
     Spec = addChild(Spec, demangleFuncSpecParam(Node::Kind::FunctionSignatureSpecializationParam));
   }
@@ -3619,6 +3621,7 @@ NodePointer Demangler::addFuncSpecParamNumber(NodePointer Param,
 NodePointer Demangler::demangleSpecAttributes(Node::Kind SpecKind) {
   bool isSerialized = nextIf('q');
   bool asyncRemoved = nextIf('a');
+  bool representationChanged = nextIf('r');
 
   int PassID = (int)nextChar() - '0';
   if (PassID < 0 || PassID >= MAX_SPECIALIZATION_PASS) {
@@ -3635,6 +3638,10 @@ NodePointer Demangler::demangleSpecAttributes(Node::Kind SpecKind) {
     SpecNd->addChild(createNode(Node::Kind::AsyncRemoved),
                      *this);
 
+  if (representationChanged)
+    SpecNd->addChild(createNode(Node::Kind::RepresentationChanged),
+                     *this);
+
   SpecNd->addChild(createNode(Node::Kind::SpecializationPassID, PassID),
                    *this);
   return SpecNd;

lib/Demangling/NodePrinter.cpp

@@ -487,6 +487,7 @@ bool NodePrinter::isSimpleType(NodePointer Node) {
   case Node::Kind::ReadAccessor:
   case Node::Kind::Read2Accessor:
   case Node::Kind::RelatedEntityDeclName:
+  case Node::Kind::RepresentationChanged:
   case Node::Kind::RetroactiveConformance:
   case Node::Kind::Setter:
   case Node::Kind::Shared:
@@ -1331,6 +1332,10 @@ void NodePrinter::printSpecializationPrefix(NodePointer node,
     }
     return;
   }
+  if (node->getFirstChild()->getKind() == Node::Kind::RepresentationChanged) {
+    Printer << "representation changed of ";
+    return;
+  }
   Printer << Description << " <";
   const char *Separator = "";
   int argNum = 0;
@@ -1429,6 +1434,10 @@ NodePointer NodePrinter::print(NodePointer Node, unsigned depth,
     Printer << "async demotion of ";
     print(Node->getChild(0), depth + 1);
     return nullptr;
+  case Node::Kind::RepresentationChanged:
+    Printer << "representation changed of ";
+    print(Node->getChild(0), depth + 1);
+    return nullptr;
   case Node::Kind::CurryThunk:
     Printer << "curry thunk of ";
     print(Node->getChild(0), depth + 1);

lib/Demangling/OldRemangler.cpp

@@ -451,6 +451,11 @@ ManglingError Remangler::mangleAsyncRemoved(Node *node, unsigned depth) {
   return ManglingError::Success;
 }
 
+ManglingError Remangler::mangleRepresentationChanged(Node *node, unsigned depth) {
+  Buffer << "r";
+  return ManglingError::Success;
+}
+
 ManglingError Remangler::mangleDroppedArgument(Node *node, unsigned depth) {
   Buffer << "t" << node->getIndex();
   return ManglingError::Success;

lib/Demangling/Remangler.cpp

@@ -1518,6 +1518,9 @@ ManglingError Remangler::mangleFunctionSignatureSpecialization(Node *node,
   Buffer << "Tf";
   bool returnValMangled = false;
   for (NodePointer Child : *node) {
+    if (Child->getKind() == Node::Kind::RepresentationChanged) {
+      returnValMangled = true;
+    }
     if (Child->getKind() == Node::Kind::FunctionSignatureSpecializationReturn) {
       Buffer << '_';
       returnValMangled = true;
@@ -3193,6 +3196,11 @@ ManglingError Remangler::mangleAsyncRemoved(Node *node, unsigned depth) {
   return ManglingError::Success;
 }
 
+ManglingError Remangler::mangleRepresentationChanged(Node *node, unsigned depth) {
+  Buffer << 'r';
+  return ManglingError::Success;
+}
+
 ManglingError Remangler::mangleDroppedArgument(Node *node, unsigned depth) {
   Buffer << "t";
   int n = node->getIndex();

test/Demangle/Inputs/manglings.txt

@@ -442,6 +442,7 @@ $s27distributed_actor_accessors7MyActorC7simple2ySSSiFTETFHF ---> accessible fun
 $s1A3bar1aySSYt_tF ---> A.bar(a: _const Swift.String) -> ()
 $s1t1fyyFSiAA3StrVcs7KeyPathCyADSiGcfu_SiADcfu0_33_556644b740b1b333fecb81e55a7cce98ADSiTf3npk_n ---> function signature specialization <Arg[1] = [Constant Propagated KeyPath : _556644b740b1b333fecb81e55a7cce98<t.Str,Swift.Int>]> of implicit closure #2 (t.Str) -> Swift.Int in implicit closure #1 (Swift.KeyPath<t.Str, Swift.Int>) -> (t.Str) -> Swift.Int in t.f() -> ()
 $s3foo4main1SVs5Int32VSbTf3npSSi3Si0_n ---> function signature specialization <Arg[1] = [Constant Propagated Struct : main.S][Constant Propagated Struct : Swift.Int32][Constant Propagated Integer : 3][Constant Propagated Struct : Swift.Bool][Constant Propagated Integer : 0]> of foo
+$e4test4BaseCyxGAA1PA2aEP3fooyyFTWTfr9 ---> representation changed of protocol witness for test.P.foo() -> () in conformance test.Base<A> : test.P in test
 $s21back_deploy_attribute0A12DeployedFuncyyFTwb ---> back deployment thunk for back_deploy_attribute.backDeployedFunc() -> ()
 $s21back_deploy_attribute0A12DeployedFuncyyFTwB ---> back deployment fallback for back_deploy_attribute.backDeployedFunc() -> ()
 $s4test3fooyyAA1P_px1TRts_XPlF ---> test.foo<A>(any test.P<Self.T == A>) -> ()