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, 45 insertions, 19 deletions

diff --git a/lib/ARCMigrate/TransZeroOutPropsInDealloc.cpp b/lib/ARCMigrate/TransZeroOutPropsInDealloc.cpp
index 7c533bcf3a..d1f08aac28 100644
--- a/lib/ARCMigrate/TransZeroOutPropsInDealloc.cpp
+++ b/lib/ARCMigrate/TransZeroOutPropsInDealloc.cpp
@@ -78,6 +78,15 @@ public:
     return true;
   }
 
+  bool VisitPseudoObjectExpr(PseudoObjectExpr *POE) {
+    if (isZeroingPropIvar(POE) && isRemovable(POE)) {
+      Transaction Trans(Pass.TA);
+      Pass.TA.removeStmt(POE);
+    }
+
+    return true;
+  }
+
   bool VisitBinaryOperator(BinaryOperator *BOE) {
     if (isZeroingPropIvar(BOE) && isRemovable(BOE)) {
       Transaction Trans(Pass.TA);
@@ -142,17 +151,21 @@ private:
   }
 
   bool isZeroingPropIvar(Expr *E) {
-    BinaryOperator *BOE = dyn_cast_or_null<BinaryOperator>(E);
-    if (!BOE) return false;
+    E = E->IgnoreParens();
+    if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E))
+      return isZeroingPropIvar(BO);
+    if (PseudoObjectExpr *PO = dyn_cast<PseudoObjectExpr>(E))
+      return isZeroingPropIvar(PO);
+    return false;
+  }
 
+  bool isZeroingPropIvar(BinaryOperator *BOE) {
     if (BOE->getOpcode() == BO_Comma)
       return isZeroingPropIvar(BOE->getLHS()) &&
              isZeroingPropIvar(BOE->getRHS());
 
     if (BOE->getOpcode() != BO_Assign)
-        return false;
-
-    ASTContext &Ctx = Pass.Ctx;
+      return false;
 
     Expr *LHS = BOE->getLHS();
     if (ObjCIvarRefExpr *IV = dyn_cast<ObjCIvarRefExpr>(LHS)) {
@@ -172,25 +185,38 @@ private:
       if (!IvarBacksPropertySynthesis)
         return false;
     }
-    else if (ObjCPropertyRefExpr *PropRefExp = dyn_cast<ObjCPropertyRefExpr>(LHS)) {
-      // TODO: Using implicit property decl.
-      if (PropRefExp->isImplicitProperty())
-        return false;
-      if (ObjCPropertyDecl *PDecl = PropRefExp->getExplicitProperty()) {
-        if (!SynthesizedProperties.count(PDecl))
-          return false;
-      }
-    }
     else
         return false;
 
-    Expr *RHS = BOE->getRHS();
-    bool RHSIsNull = RHS->isNullPointerConstant(Ctx,
-                                                Expr::NPC_ValueDependentIsNull);
-    if (RHSIsNull)
+    return isZero(BOE->getRHS());
+  }
+
+  bool isZeroingPropIvar(PseudoObjectExpr *PO) {
+    BinaryOperator *BO = dyn_cast<BinaryOperator>(PO->getSyntacticForm());
+    if (!BO) return false;
+    if (BO->getOpcode() != BO_Assign) return false;
+
+    ObjCPropertyRefExpr *PropRefExp =
+      dyn_cast<ObjCPropertyRefExpr>(BO->getLHS()->IgnoreParens());
+    if (!PropRefExp) return false;
+
+    // TODO: Using implicit property decl.
+    if (PropRefExp->isImplicitProperty())
+      return false;
+
+    if (ObjCPropertyDecl *PDecl = PropRefExp->getExplicitProperty()) {
+      if (!SynthesizedProperties.count(PDecl))
+        return false;
+    }
+
+    return isZero(cast<OpaqueValueExpr>(BO->getRHS())->getSourceExpr());
+  }
+
+  bool isZero(Expr *E) {
+    if (E->isNullPointerConstant(Pass.Ctx, Expr::NPC_ValueDependentIsNull))
       return true;
 
-    return isZeroingPropIvar(RHS);
+    return isZeroingPropIvar(E);
   }
 };