demangler: classify allocating init functions as thunks

rdar://problem/45170658

Author: eeckstein

include/swift/Demangling/Demangle.h

@@ -357,7 +357,7 @@ class Context {
   /// Returns true if the mangledName refers to a thunk function.
   ///
   /// Thunk functions are either (ObjC) partial apply forwarder, swift-as-ObjC
-  /// or ObjC-as-swift thunks.
+  /// or ObjC-as-swift thunks or allocating init functions.
   bool isThunkSymbol(llvm::StringRef MangledName);
 
   /// Returns the mangled name of the target of a thunk.

lib/Demangling/Context.cpp

@@ -77,7 +77,8 @@ bool Context::isThunkSymbol(llvm::StringRef MangledName) {
         MangledName.endswith("TO") ||  // ObjC-as-swift thunk
         MangledName.endswith("TR") ||  // reabstraction thunk helper function
         MangledName.endswith("Tr") ||  // reabstraction thunk
-        MangledName.endswith("TW")) {  // protocol witness thunk
+        MangledName.endswith("TW") ||  // protocol witness thunk
+        MangledName.endswith("fC")) {  // allocating constructor
 
       // To avoid false positives, we need to fully demangle the symbol.
       NodePointer Nd = D->demangleSymbol(MangledName);
@@ -93,6 +94,7 @@ bool Context::isThunkSymbol(llvm::StringRef MangledName) {
         case Node::Kind::ReabstractionThunkHelper:
         case Node::Kind::ReabstractionThunk:
         case Node::Kind::ProtocolWitness:
+        case Node::Kind::Allocator:
           return true;
         default:
           break;
@@ -125,6 +127,12 @@ std::string Context::getThunkTarget(llvm::StringRef MangledName) {
         MangledName.endswith("TW") )
       return std::string();
 
+    if (MangledName.endswith("fC")) {
+      std::string target = MangledName.str();
+      target[target.size() - 1] = 'c';
+      return target;
+    }
+
     return MangledName.substr(0, MangledName.size() - 2).str();
   }
   // Old mangling.

test/Demangle/Inputs/manglings.txt

@@ -286,7 +286,7 @@ _T03nix6testitSaySiGyFTv0_ ---> outlined variable #1 of nix.testit() -> [Swift.I
 _T0So11UITextFieldC4textSSSgvgToTepb_ ---> outlined bridged method (pb) of @objc __C.UITextField.text.getter : Swift.String?
 _T0So11UITextFieldC4textSSSgvgToTeab_ ---> outlined bridged method (ab) of @objc __C.UITextField.text.getter : Swift.String?
 _T04test1SVyxGAA1RA2A1ZRzAA1Y2ZZRpzl1A_AhaGPWT ---> {C} associated type witness table accessor for A.ZZ : test.Y in <A where A: test.Z, A.ZZ: test.Y> test.S<A> : test.R in test
-_T0s24_UnicodeScalarExceptions33_0E4228093681F6920F0AB2E48B4F1C69LLVACycfC ---> Swift.(_UnicodeScalarExceptions in _0E4228093681F6920F0AB2E48B4F1C69).init() -> Swift.(_UnicodeScalarExceptions in _0E4228093681F6920F0AB2E48B4F1C69)
+_T0s24_UnicodeScalarExceptions33_0E4228093681F6920F0AB2E48B4F1C69LLVACycfC ---> {T:_T0s24_UnicodeScalarExceptions33_0E4228093681F6920F0AB2E48B4F1C69LLVACycfc} Swift.(_UnicodeScalarExceptions in _0E4228093681F6920F0AB2E48B4F1C69).init() -> Swift.(_UnicodeScalarExceptions in _0E4228093681F6920F0AB2E48B4F1C69)
 _T0D ---> _T0D
 _T0s18EnumeratedIteratorVyxGs8Sequencess0B8ProtocolRzlsADP5splitSay03SubC0QzGSi9maxSplits_Sb25omittingEmptySubsequencesSb7ElementQzKc14whereSeparatortKFTW ---> {T:} protocol witness for Swift.Sequence.split(maxSplits: Swift.Int, omittingEmptySubsequences: Swift.Bool, whereSeparator: (A.Element) throws -> Swift.Bool) throws -> [A.SubSequence] in conformance <A where A: Swift.IteratorProtocol> Swift.EnumeratedIterator<A> : Swift.Sequence in Swift
 _T0s3SetVyxGs10CollectiotySivm ---> _T0s3SetVyxGs10CollectiotySivm
@@ -334,4 +334,5 @@ $S18resilient_protocol21ResilientBaseProtocolTL ---> protocol requirements base
 $S1t1PP10AssocType2_AA1QTn ---> associated conformance descriptor for t.P.AssocType2: t.Q
 $S1t1PP10AssocType2_AA1QTN ---> default associated conformance accessor for t.P.AssocType2: t.Q
 $sSD5IndexVy__GD ---> $sSD5IndexVy__GD
+$s4test3StrCACycfC ---> {T:$s4test3StrCACycfc} test.Str.__allocating_init() -> test.Str