Add a new expression node, CXXOperatorCallExpr, which expresses a
function call created in response to the use of operator syntax that
resolves to an overloaded operator in C++, e.g., "str1 +
str2" that resolves to std::operator+(str1, str2)". We now build a
CXXOperatorCallExpr in C++ when we pick an overloaded operator. (But
only for binary operators, where we actually implement overloading)

I decided *not* to refactor the current CallExpr to make it abstract
(with FunctionCallExpr and CXXOperatorCallExpr as derived
classes). Doing so would allow us to make CXXOperatorCallExpr a little
bit smaller, at the cost of making the argument and callee accessors
virtual. We won't know if this is going to be a win until we can parse
lots of C++ code to determine how much memory we'll save by making
this change vs. the performance penalty due to the extra virtual
calls.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@59306 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index 249bebc..871dc4b 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -101,6 +101,15 @@
 // Postfix Operators.
 //===----------------------------------------------------------------------===//
 
+CallExpr::CallExpr(StmtClass SC, Expr *fn, Expr **args, unsigned numargs, 
+                   QualType t, SourceLocation rparenloc)
+  : Expr(SC, t), NumArgs(numargs) {
+  SubExprs = new Stmt*[numargs+1];
+  SubExprs[FN] = fn;
+  for (unsigned i = 0; i != numargs; ++i)
+    SubExprs[i+ARGS_START] = args[i];
+  RParenLoc = rparenloc;
+}
 
 CallExpr::CallExpr(Expr *fn, Expr **args, unsigned numargs, QualType t,
                    SourceLocation rparenloc)
@@ -285,6 +294,7 @@
     return getType().isVolatileQualified();
 
   case CallExprClass:
+  case CXXOperatorCallExprClass:
     // TODO: check attributes for pure/const.   "void foo() { strlen("bar"); }"
     // should warn.
     return true;
@@ -410,7 +420,8 @@
     //   An assignment expression [...] is not an lvalue.
     return LV_InvalidExpression;
   }
-  case CallExprClass: {
+  case CallExprClass: 
+  case CXXOperatorCallExprClass: {
     // C++ [expr.call]p10:
     //   A function call is an lvalue if and only if the result type
     //   is a reference.
@@ -586,7 +597,8 @@
   case CXXBoolLiteralExprClass:
   case AddrLabelExprClass:
     return true;
-  case CallExprClass: {
+  case CallExprClass: 
+  case CXXOperatorCallExprClass: {
     const CallExpr *CE = cast<CallExpr>(this);
 
     // Allow any constant foldable calls to builtins.
@@ -777,7 +789,8 @@
                                     T1.getUnqualifiedType());
     break;
   }
-  case CallExprClass: {
+  case CallExprClass: 
+  case CXXOperatorCallExprClass: {
     const CallExpr *CE = cast<CallExpr>(this);
     Result.zextOrTrunc(static_cast<uint32_t>(Ctx.getTypeSize(getType())));
     
diff --git a/lib/AST/ExprCXX.cpp b/lib/AST/ExprCXX.cpp
index ff97e68..22f30f4 100644
--- a/lib/AST/ExprCXX.cpp
+++ b/lib/AST/ExprCXX.cpp
@@ -11,6 +11,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "clang/Basic/IdentifierTable.h"
+#include "clang/AST/DeclCXX.h"
 #include "clang/AST/ExprCXX.h"
 using namespace clang;
 
@@ -75,6 +77,52 @@
   return child_iterator();
 }
 
+OverloadedOperatorKind CXXOperatorCallExpr::getOperator() const {
+  // All simple function calls (e.g. func()) are implicitly cast to pointer to
+  // function. As a result, we try and obtain the DeclRefExpr from the 
+  // ImplicitCastExpr.
+  const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(getCallee());
+  if (!ICE) // FIXME: deal with more complex calls (e.g. (func)(), (*func)()).
+    return OO_None;
+  
+  const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr());
+  if (!DRE)
+    return OO_None;
+  
+  if (const FunctionDecl *FDecl = dyn_cast<FunctionDecl>(DRE->getDecl()))
+    return FDecl->getIdentifier()->getOverloadedOperatorID();  
+  else if (const OverloadedFunctionDecl *Ovl 
+             = dyn_cast<OverloadedFunctionDecl>(DRE->getDecl()))
+    return Ovl->getIdentifier()->getOverloadedOperatorID();
+  else
+    return OO_None;
+}
+
+SourceRange CXXOperatorCallExpr::getSourceRange() const {
+  OverloadedOperatorKind Kind = getOperator();
+  if (Kind == OO_PlusPlus || Kind == OO_MinusMinus) {
+    if (getNumArgs() == 1)
+      // Prefix operator
+      return SourceRange(getOperatorLoc(), 
+                         getArg(0)->getSourceRange().getEnd());
+    else
+      // Postfix operator
+      return SourceRange(getArg(0)->getSourceRange().getEnd(),
+                         getOperatorLoc());
+  } else if (Kind == OO_Call) {
+    return SourceRange(getArg(0)->getSourceRange().getBegin(), getRParenLoc());
+  } else if (Kind == OO_Subscript) {
+    return SourceRange(getArg(0)->getSourceRange().getBegin(), getRParenLoc());
+  } else if (getNumArgs() == 1) {
+    return SourceRange(getOperatorLoc(), getArg(0)->getSourceRange().getEnd());
+  } else if (getNumArgs() == 2) {
+    return SourceRange(getArg(0)->getSourceRange().getBegin(),
+                       getArg(1)->getSourceRange().getEnd());
+  } else {
+    return SourceRange();
+  }
+}
+
 //===----------------------------------------------------------------------===//
 //  Named casts
 //===----------------------------------------------------------------------===//
diff --git a/lib/AST/StmtPrinter.cpp b/lib/AST/StmtPrinter.cpp
index bbd53d0..cf6d4c0 100644
--- a/lib/AST/StmtPrinter.cpp
+++ b/lib/AST/StmtPrinter.cpp
@@ -811,6 +811,49 @@
 }
 
 // C++
+void StmtPrinter::VisitCXXOperatorCallExpr(CXXOperatorCallExpr *Node) {
+  const char *OpStrings[NUM_OVERLOADED_OPERATORS] = {
+    "",
+#define OVERLOADED_OPERATOR(Name,Spelling,Token,Unary,Binary,MemberOnly) \
+    Spelling,
+#include "clang/Basic/OperatorKinds.def"
+  };
+
+  OverloadedOperatorKind Kind = Node->getOperator();
+  if (Kind == OO_PlusPlus || Kind == OO_MinusMinus) {
+    if (Node->getNumArgs() == 1) {
+      OS << OpStrings[Kind] << ' ';
+      PrintExpr(Node->getArg(0));
+    } else {
+      PrintExpr(Node->getArg(0));
+      OS << ' ' << OpStrings[Kind];
+    }
+  } else if (Kind == OO_Call) {
+    PrintExpr(Node->getArg(0));
+    OS << '(';
+    for (unsigned ArgIdx = 1; ArgIdx < Node->getNumArgs(); ++ArgIdx) {
+      if (ArgIdx > 1)
+        OS << ", ";
+      if (!isa<CXXDefaultArgExpr>(Node->getArg(ArgIdx)))
+        PrintExpr(Node->getArg(ArgIdx));
+    }
+    OS << ')';
+  } else if (Kind == OO_Subscript) {
+    PrintExpr(Node->getArg(0));
+    OS << '[';
+    PrintExpr(Node->getArg(1));
+    OS << ']';
+  } else if (Node->getNumArgs() == 1) {
+    OS << OpStrings[Kind] << ' ';
+    PrintExpr(Node->getArg(0));
+  } else if (Node->getNumArgs() == 2) {
+    PrintExpr(Node->getArg(0));
+    OS << ' ' << OpStrings[Kind] << ' ';
+    PrintExpr(Node->getArg(1));
+  } else {
+    assert(false && "unknown overloaded operator");
+  }
+}
 
 void StmtPrinter::VisitCXXNamedCastExpr(CXXNamedCastExpr *Node) {
   OS << Node->getCastName() << '<';
diff --git a/lib/AST/StmtSerialization.cpp b/lib/AST/StmtSerialization.cpp
index 667f597..268922e 100644
--- a/lib/AST/StmtSerialization.cpp
+++ b/lib/AST/StmtSerialization.cpp
@@ -53,7 +53,7 @@
       return BreakStmt::CreateImpl(D, C);
      
     case CallExprClass:
-      return CallExpr::CreateImpl(D, C);
+      return CallExpr::CreateImpl(D, C, CallExprClass);
       
     case CaseStmtClass:
       return CaseStmt::CreateImpl(D, C);
@@ -198,6 +198,9 @@
     //    C++
     //==--------------------------------------==//
       
+    case CXXOperatorCallExprClass:
+      return CXXOperatorCallExpr::CreateImpl(D, C, CXXOperatorCallExprClass);
+
     case CXXDefaultArgExprClass:
       return CXXDefaultArgExpr::CreateImpl(D, C);      
 
@@ -361,14 +364,14 @@
   S.BatchEmitOwnedPtrs(NumArgs+1, SubExprs);  
 }
 
-CallExpr* CallExpr::CreateImpl(Deserializer& D, ASTContext& C) {
+CallExpr* CallExpr::CreateImpl(Deserializer& D, ASTContext& C, StmtClass SC) {
   QualType t = QualType::ReadVal(D);
   SourceLocation L = SourceLocation::ReadVal(D);
   unsigned NumArgs = D.ReadInt();
   Stmt** SubExprs = new Stmt*[NumArgs+1];
   D.BatchReadOwnedPtrs(NumArgs+1, SubExprs, C);
 
-  return new CallExpr(SubExprs,NumArgs,t,L);  
+  return new CallExpr(SC, SubExprs,NumArgs,t,L);  
 }
 
 void CaseStmt::EmitImpl(Serializer& S) const {
diff --git a/lib/Analysis/GRExprEngine.cpp b/lib/Analysis/GRExprEngine.cpp
index cb7c7fe..545d869 100644
--- a/lib/Analysis/GRExprEngine.cpp
+++ b/lib/Analysis/GRExprEngine.cpp
@@ -311,7 +311,8 @@
       break;
     }
       
-    case Stmt::CallExprClass: {
+    case Stmt::CallExprClass:
+    case Stmt::CXXOperatorCallExprClass: {
       CallExpr* C = cast<CallExpr>(S);
       VisitCall(C, Pred, C->arg_begin(), C->arg_end(), Dst);
       break;      
diff --git a/lib/Basic/IdentifierTable.cpp b/lib/Basic/IdentifierTable.cpp
index b868475..4d737c5 100644
--- a/lib/Basic/IdentifierTable.cpp
+++ b/lib/Basic/IdentifierTable.cpp
@@ -189,11 +189,22 @@
 #include "clang/Basic/TokenKinds.def"
 }
 
+/// addOperatorPrefix - Add the prefix "operator" (possible with a
+/// space after it) to the given operator symbol, and return the
+/// result.
+static std::string addOperatorPrefix(const char* Symbol) {
+  std::string result = "operator";
+  if (Symbol[0] >= 'a' && Symbol[0] <= 'z')
+    result += ' ';
+  result += Symbol;
+  return result;
+}
+
 /// AddOverloadedOperators - Register the name of all C++ overloadable
 /// operators ("operator+", "operator[]", etc.)
 void IdentifierTable::AddOverloadedOperators() {
 #define OVERLOADED_OPERATOR(Name,Spelling,Token, Unary, Binary, MemberOnly) \
-  OverloadedOperators[OO_##Name] = &get(Spelling);                      \
+  OverloadedOperators[OO_##Name] = &get(addOperatorPrefix(Spelling));   \
   OverloadedOperators[OO_##Name]->setOverloadedOperatorID(OO_##Name);
 #include "clang/Basic/OperatorKinds.def"
 }
diff --git a/lib/CodeGen/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp
index ad2f78b..5f50017 100644
--- a/lib/CodeGen/CGExpr.cpp
+++ b/lib/CodeGen/CGExpr.cpp
@@ -113,7 +113,9 @@
 
   case Expr::BinaryOperatorClass: 
     return EmitBinaryOperatorLValue(cast<BinaryOperator>(E));
-  case Expr::CallExprClass: return EmitCallExprLValue(cast<CallExpr>(E));
+  case Expr::CallExprClass: 
+  case Expr::CXXOperatorCallExprClass:
+    return EmitCallExprLValue(cast<CallExpr>(E));
   case Expr::DeclRefExprClass: return EmitDeclRefLValue(cast<DeclRefExpr>(E));
   case Expr::ParenExprClass:return EmitLValue(cast<ParenExpr>(E)->getSubExpr());
   case Expr::PredefinedExprClass:
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 6dd9fa7..76835bc 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -1237,6 +1237,7 @@
   case Expr::ObjCStringLiteralClass:
     return false;
   case Expr::CallExprClass:
+  case Expr::CXXOperatorCallExprClass:
     // __builtin___CFStringMakeConstantString is a valid constant l-value.
     if (cast<CallExpr>(Init)->isBuiltinCall() == 
            Builtin::BI__builtin___CFStringMakeConstantString)
@@ -1432,7 +1433,8 @@
   case Expr::TypesCompatibleExprClass:
   case Expr::CXXBoolLiteralExprClass:
     return false;
-  case Expr::CallExprClass: {
+  case Expr::CallExprClass: 
+  case Expr::CXXOperatorCallExprClass: {
     const CallExpr *CE = cast<CallExpr>(Init);
 
     // Allow any constant foldable calls to builtins.
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index c9f311a..686a8f4 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -2851,12 +2851,12 @@
         ResultTy = ResultTy.getNonReferenceType();
         
         // Build the actual expression node.
-        // FIXME: We lose the fact that we have a function here!
-        if (Opc > BinaryOperator::Assign && Opc <= BinaryOperator::OrAssign)
-          return new CompoundAssignOperator(lhs, rhs, Opc, ResultTy, ResultTy,
-                                            TokLoc);
-        else
-          return new BinaryOperator(lhs, rhs, Opc, ResultTy, TokLoc);
+        Expr *FnExpr = new DeclRefExpr(FnDecl, FnDecl->getType(), 
+                                       SourceLocation());
+        UsualUnaryConversions(FnExpr);
+
+        Expr *Args[2] = { lhs, rhs };
+        return new CXXOperatorCallExpr(FnExpr, Args, 2, ResultTy, TokLoc);
       } else {
         // We matched a built-in operator. Convert the arguments, then
         // break out so that we will build the appropriate built-in