Change the AST representation of operations on Objective-C

property references to use a new PseudoObjectExpr
expression which pairs a syntactic form of the expression
with a set of semantic expressions implementing it.
This should significantly reduce the complexity required
elsewhere in the compiler to deal with these kinds of
expressions (e.g. IR generation's special l-value kind,
the static analyzer's Message abstraction), at the lower
cost of specifically dealing with the odd AST structure
of these expressions.  It should also greatly simplify
efforts to implement similar language features in the
future, most notably Managed C++'s properties and indexed
properties.

Most of the effort here is in dealing with the various
clients of the AST.  I've gone ahead and simplified the
ObjC rewriter's use of properties;  other clients, like
IR-gen and the static analyzer, have all the old
complexity *and* all the new complexity, at least
temporarily.  Many thanks to Ted for writing and advising
on the necessary changes to the static analyzer.

I've xfailed a small diagnostics regression in the static
analyzer at Ted's request.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@143867 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 82 insertions, 0 deletions

diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index 3239973688..6eb6116b01 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -1694,6 +1694,19 @@ bool Expr::isUnusedResultAWarning(SourceLocation &Loc, SourceRange &R1,
     R1 = getSourceRange();
     return true;
 
+  case PseudoObjectExprClass: {
+    const PseudoObjectExpr *PO = cast<PseudoObjectExpr>(this);
+
+    // Only complain about things that have the form of a getter.
+    if (isa<UnaryOperator>(PO->getSyntacticForm()) ||
+        isa<BinaryOperator>(PO->getSyntacticForm()))
+      return false;
+
+    Loc = getExprLoc();
+    R1 = getSourceRange();
+    return true;
+  }
+
   case StmtExprClass: {
     // Statement exprs don't logically have side effects themselves, but are
     // sometimes used in macros in ways that give them a type that is unused.
@@ -2598,6 +2611,9 @@ Expr::isNullPointerConstant(ASTContext &Ctx,
   } else if (const MaterializeTemporaryExpr *M 
                                    = dyn_cast<MaterializeTemporaryExpr>(this)) {
     return M->GetTemporaryExpr()->isNullPointerConstant(Ctx, NPC);
+  } else if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(this)) {
+    if (const Expr *Source = OVE->getSourceExpr())
+      return Source->isNullPointerConstant(Ctx, NPC);
   }
 
   // C++0x nullptr_t is always a null pointer constant.
@@ -3306,6 +3322,72 @@ const OpaqueValueExpr *OpaqueValueExpr::findInCopyConstruct(const Expr *e) {
   return cast<OpaqueValueExpr>(e);
 }
 
+PseudoObjectExpr *PseudoObjectExpr::Create(ASTContext &Context, EmptyShell sh,
+                                           unsigned numSemanticExprs) {
+  void *buffer = Context.Allocate(sizeof(PseudoObjectExpr) +
+                                    (1 + numSemanticExprs) * sizeof(Expr*),
+                                  llvm::alignOf<PseudoObjectExpr>());
+  return new(buffer) PseudoObjectExpr(sh, numSemanticExprs);
+}
+
+PseudoObjectExpr::PseudoObjectExpr(EmptyShell shell, unsigned numSemanticExprs)
+  : Expr(PseudoObjectExprClass, shell) {
+  PseudoObjectExprBits.NumSubExprs = numSemanticExprs + 1;
+}
+
+PseudoObjectExpr *PseudoObjectExpr::Create(ASTContext &C, Expr *syntax,
+                                           ArrayRef<Expr*> semantics,
+                                           unsigned resultIndex) {
+  assert(syntax && "no syntactic expression!");
+  assert(semantics.size() && "no semantic expressions!");
+
+  QualType type;
+  ExprValueKind VK;
+  if (resultIndex == NoResult) {
+    type = C.VoidTy;
+    VK = VK_RValue;
+  } else {
+    assert(resultIndex < semantics.size());
+    type = semantics[resultIndex]->getType();
+    VK = semantics[resultIndex]->getValueKind();
+    assert(semantics[resultIndex]->getObjectKind() == OK_Ordinary);
+  }
+
+  void *buffer = C.Allocate(sizeof(PseudoObjectExpr) +
+                              (1 + semantics.size()) * sizeof(Expr*),
+                            llvm::alignOf<PseudoObjectExpr>());
+  return new(buffer) PseudoObjectExpr(type, VK, syntax, semantics,
+                                      resultIndex);
+}
+
+PseudoObjectExpr::PseudoObjectExpr(QualType type, ExprValueKind VK,
+                                   Expr *syntax, ArrayRef<Expr*> semantics,
+                                   unsigned resultIndex)
+  : Expr(PseudoObjectExprClass, type, VK, OK_Ordinary,
+         /*filled in at end of ctor*/ false, false, false, false) {
+  PseudoObjectExprBits.NumSubExprs = semantics.size() + 1;
+  PseudoObjectExprBits.ResultIndex = resultIndex + 1;
+
+  for (unsigned i = 0, e = semantics.size() + 1; i != e; ++i) {
+    Expr *E = (i == 0 ? syntax : semantics[i-1]);
+    getSubExprsBuffer()[i] = E;
+
+    if (E->isTypeDependent())
+      ExprBits.TypeDependent = true;
+    if (E->isValueDependent())
+      ExprBits.ValueDependent = true;
+    if (E->isInstantiationDependent())
+      ExprBits.InstantiationDependent = true;
+    if (E->containsUnexpandedParameterPack())
+      ExprBits.ContainsUnexpandedParameterPack = true;
+
+    if (isa<OpaqueValueExpr>(E))
+      assert(cast<OpaqueValueExpr>(E)->getSourceExpr() != 0 &&
+             "opaque-value semantic expressions for pseudo-object "
+             "operations must have sources");
+  }
+}
+
 //===----------------------------------------------------------------------===//
 //  ExprIterator.
 //===----------------------------------------------------------------------===//