AST: Mangle cast expression encoding more accurately

[majnemer]

Summary

Don't mangle all casts in expressions as "cv", use the appropriate
encoding which corresponds to a specific cast.

This fixes PR21034.

[majnemer]

Closed by commit rL218293 (authored by @majnemer).

lib/AST/ItaniumMangle.cpp

#include "clang/AST/TypeNodes.def"
   void mangleAArch64NeonVectorType(const VectorType *T);
 
   void mangleIntegerLiteral(QualType T, const llvm::APSInt &Value);
   void mangleMemberExpr(const Expr *base, bool isArrow,
                         NestedNameSpecifier *qualifier,
                         NamedDecl *firstQualifierLookup,
                         DeclarationName name,
                         unsigned knownArity);
+  void mangleCastExpression(const Expr *E, StringRef CastEncoding);
   void mangleExpression(const Expr *E, unsigned Arity = UnknownArity);
   void mangleCXXCtorType(CXXCtorType T);
   void mangleCXXDtorType(CXXDtorType T);
 
   void mangleTemplateArgs(const ASTTemplateArgumentListInfo &TemplateArgs);
   void mangleTemplateArgs(const TemplateArgument *TemplateArgs,
                           unsigned NumTemplateArgs);
   void mangleTemplateArgs(const TemplateArgumentList &AL);
static bool isParenthesizedADLCallee(const CallExpr *call) {
   if (lookup->getNumDecls() > 0 &&
       (*lookup->decls_begin())->isCXXClassMember())
     return false;
 
   // Otherwise, ADL would have been triggered.
   return true;
 }
 
+void CXXNameMangler::mangleCastExpression(const Expr *E, StringRef CastEncoding) {
+  const ExplicitCastExpr *ECE = cast<ExplicitCastExpr>(E);
+  Out << CastEncoding;
+  mangleType(ECE->getType());
+  mangleExpression(ECE->getSubExpr());
+}
+
 void CXXNameMangler::mangleExpression(const Expr *E, unsigned Arity) {
   // <expression> ::= <unary operator-name> <expression>
   //              ::= <binary operator-name> <expression> <expression>
   //              ::= <trinary operator-name> <expression> <expression> <expression>
   //              ::= cv <type> expression           # conversion with one argument
   //              ::= cv <type> _ <expression>* E # conversion with a different number of arguments
+  //              ::= dc <type> <expression>         # dynamic_cast<type> (expression)
+  //              ::= sc <type> <expression>         # static_cast<type> (expression)
+  //              ::= cc <type> <expression>         # const_cast<type> (expression)
+  //              ::= rc <type> <expression>         # reinterpret_cast<type> (expression)
   //              ::= st <type>                      # sizeof (a type)
   //              ::= at <type>                      # alignof (a type)
   //              ::= <template-param>
   //              ::= <function-param>
   //              ::= sr <type> <unqualified-name>                   # dependent name
   //              ::= sr <type> <unqualified-name> <template-args>   # dependent template-id
   //              ::= ds <expression> <expression>                   # expr.*expr
   //              ::= sZ <template-param>                            # size of a parameter pack
case Expr::ObjCBridgedCastExprClass: {
     // Mangle ownership casts as a vendor extended operator __bridge, 
     // __bridge_transfer, or __bridge_retain.
     StringRef Kind = cast<ObjCBridgedCastExpr>(E)->getBridgeKindName();
     Out << "v1U" << Kind.size() << Kind;
   }
   // Fall through to mangle the cast itself.
       
   case Expr::CStyleCastExprClass:
+  case Expr::CXXFunctionalCastExprClass: {
+    mangleCastExpression(E, "cv");
+    break;
+  }
+
   case Expr::CXXStaticCastExprClass:
+    mangleCastExpression(E, "sc");
+    break;
   case Expr::CXXDynamicCastExprClass:
+    mangleCastExpression(E, "dc");
+    break;
   case Expr::CXXReinterpretCastExprClass:
+    mangleCastExpression(E, "rc");
+    break;
   case Expr::CXXConstCastExprClass:
-  case Expr::CXXFunctionalCastExprClass: {
-    const ExplicitCastExpr *ECE = cast<ExplicitCastExpr>(E);
-    Out << "cv";
-    mangleType(ECE->getType());
-    mangleExpression(ECE->getSubExpr());
+    mangleCastExpression(E, "cc");
     break;
-  }
 
   case Expr::CXXOperatorCallExprClass: {
     const CXXOperatorCallExpr *CE = cast<CXXOperatorCallExpr>(E);
     unsigned NumArgs = CE->getNumArgs();
     mangleOperatorName(CE->getOperator(), /*Arity=*/NumArgs);
     // Mangle the arguments.
     for (unsigned i = 0; i != NumArgs; ++i)
       mangleExpression(CE->getArg(i));

test/CodeGenCXX/mangle-exprs.cpp

namespace Casts {
   template <int N> T<N> f() { return T<N>(); }
   
   // CHECK-LABEL: define weak_odr void @_ZN5Casts8implicitILj4EEEvPN9enable_ifIXleT_Li4EEvE4typeE
   template void implicit<4>(void*);
   // CHECK-LABEL: define weak_odr void @_ZN5Casts6cstyleILj4EEEvPN9enable_ifIXleT_cvjLi4EEvE4typeE
   template void cstyle<4>(void*);
   // CHECK-LABEL: define weak_odr void @_ZN5Casts10functionalILj4EEEvPN9enable_ifIXleT_cvjLi4EEvE4typeE
   template void functional<4>(void*);
-  // CHECK-LABEL: define weak_odr void @_ZN5Casts7static_ILj4EEEvPN9enable_ifIXleT_cvjLi4EEvE4typeE
+  // CHECK-LABEL: define weak_odr void @_ZN5Casts7static_ILj4EEEvPN9enable_ifIXleT_scjLi4EEvE4typeE
   template void static_<4>(void*);
 
   // CHECK-LABEL: define weak_odr void @_ZN5Casts1fILi6EEENS_1TIXT_EEEv
   template T<6> f<6>();
 
   // CHECK-LABEL: define weak_odr void @_ZN5Casts5auto_IiEEvDTnw_DapicvT__EEE(
   template void auto_<int>(int*);