1 files changed, 228 insertions, 0 deletions
diff --git a/clang/lib/ARCMigrate/TransZeroOutPropsInDealloc.cpp b/clang/lib/ARCMigrate/TransZeroOutPropsInDealloc.cpp
new file mode 100644
index 0000000..d1f08aa
--- /dev/null
+++ b/clang/lib/ARCMigrate/TransZeroOutPropsInDealloc.cpp
@@ -0,0 +1,228 @@
+//===--- TransZeroOutPropsInDealloc.cpp - Tranformations to ARC mode ------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// removeZeroOutPropsInDealloc:
+//
+// Removes zero'ing out "strong" @synthesized properties in a -dealloc method.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Transforms.h"
+#include "Internals.h"
+
+using namespace clang;
+using namespace arcmt;
+using namespace trans;
+
+namespace {
+
+class ZeroOutInDeallocRemover :
+                           public RecursiveASTVisitor<ZeroOutInDeallocRemover> {
+  typedef RecursiveASTVisitor<ZeroOutInDeallocRemover> base;
+
+  MigrationPass &Pass;
+
+  llvm::DenseMap<ObjCPropertyDecl*, ObjCPropertyImplDecl*> SynthesizedProperties;
+  ImplicitParamDecl *SelfD;
+  ExprSet Removables;
+  Selector FinalizeSel;
+
+public:
+  ZeroOutInDeallocRemover(MigrationPass &pass) : Pass(pass), SelfD(0) {
+    FinalizeSel =
+        Pass.Ctx.Selectors.getNullarySelector(&Pass.Ctx.Idents.get("finalize"));
+  }
+
+  bool VisitObjCMessageExpr(ObjCMessageExpr *ME) {
+    ASTContext &Ctx = Pass.Ctx;
+    TransformActions &TA = Pass.TA;
+
+    if (ME->getReceiverKind() != ObjCMessageExpr::Instance)
+      return true;
+    Expr *receiver = ME->getInstanceReceiver();
+    if (!receiver)
+      return true;
+
+    DeclRefExpr *refE = dyn_cast<DeclRefExpr>(receiver->IgnoreParenCasts());
+    if (!refE || refE->getDecl() != SelfD)
+      return true;
+
+    bool BackedBySynthesizeSetter = false;
+    for (llvm::DenseMap<ObjCPropertyDecl*, ObjCPropertyImplDecl*>::iterator
+         P = SynthesizedProperties.begin(), 
+         E = SynthesizedProperties.end(); P != E; ++P) {
+      ObjCPropertyDecl *PropDecl = P->first;
+      if (PropDecl->getSetterName() == ME->getSelector()) {
+        BackedBySynthesizeSetter = true;
+        break;
+      }
+    }
+    if (!BackedBySynthesizeSetter)
+      return true;
+    
+    // Remove the setter message if RHS is null
+    Transaction Trans(TA);
+    Expr *RHS = ME->getArg(0);
+    bool RHSIsNull = 
+      RHS->isNullPointerConstant(Ctx,
+                                 Expr::NPC_ValueDependentIsNull);
+    if (RHSIsNull && isRemovable(ME))
+      TA.removeStmt(ME);
+
+    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);
+      Pass.TA.removeStmt(BOE);
+    }
+
+    return true;
+  }
+
+  bool TraverseObjCMethodDecl(ObjCMethodDecl *D) {
+    if (D->getMethodFamily() != OMF_dealloc &&
+        !(D->isInstanceMethod() && D->getSelector() == FinalizeSel))
+      return true;
+    if (!D->hasBody())
+      return true;
+
+    ObjCImplDecl *IMD = dyn_cast<ObjCImplDecl>(D->getDeclContext());
+    if (!IMD)
+      return true;
+
+    SelfD = D->getSelfDecl();
+    collectRemovables(D->getBody(), Removables);
+
+    // For a 'dealloc' method use, find all property implementations in
+    // this class implementation.
+    for (ObjCImplDecl::propimpl_iterator
+           I = IMD->propimpl_begin(), EI = IMD->propimpl_end(); I != EI; ++I) {
+        ObjCPropertyImplDecl *PID = *I;
+        if (PID->getPropertyImplementation() ==
+            ObjCPropertyImplDecl::Synthesize) {
+          ObjCPropertyDecl *PD = PID->getPropertyDecl();
+          ObjCMethodDecl *setterM = PD->getSetterMethodDecl();
+          if (!(setterM && setterM->isDefined())) {
+            ObjCPropertyDecl::PropertyAttributeKind AttrKind = 
+              PD->getPropertyAttributes();
+              if (AttrKind & 
+                  (ObjCPropertyDecl::OBJC_PR_retain | 
+                   ObjCPropertyDecl::OBJC_PR_copy   |
+                   ObjCPropertyDecl::OBJC_PR_strong))
+                SynthesizedProperties[PD] = PID;
+          }
+        }
+    }
+
+    // Now, remove all zeroing of ivars etc.
+    base::TraverseObjCMethodDecl(D);
+
+    // clear out for next method.
+    SynthesizedProperties.clear();
+    SelfD = 0;
+    Removables.clear();
+    return true;
+  }
+
+  bool TraverseFunctionDecl(FunctionDecl *D) { return true; }
+  bool TraverseBlockDecl(BlockDecl *block) { return true; }
+  bool TraverseBlockExpr(BlockExpr *block) { return true; }
+
+private:
+  bool isRemovable(Expr *E) const {
+    return Removables.count(E);
+  }
+
+  bool isZeroingPropIvar(Expr *E) {
+    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;
+
+    Expr *LHS = BOE->getLHS();
+    if (ObjCIvarRefExpr *IV = dyn_cast<ObjCIvarRefExpr>(LHS)) {
+      ObjCIvarDecl *IVDecl = IV->getDecl();
+      if (!IVDecl->getType()->isObjCObjectPointerType())
+        return false;
+      bool IvarBacksPropertySynthesis = false;
+      for (llvm::DenseMap<ObjCPropertyDecl*, ObjCPropertyImplDecl*>::iterator
+           P = SynthesizedProperties.begin(), 
+           E = SynthesizedProperties.end(); P != E; ++P) {
+        ObjCPropertyImplDecl *PropImpDecl = P->second;
+        if (PropImpDecl && PropImpDecl->getPropertyIvarDecl() == IVDecl) {
+          IvarBacksPropertySynthesis = true;
+          break;
+        }
+      }
+      if (!IvarBacksPropertySynthesis)
+        return false;
+    }
+    else
+        return false;
+
+    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(E);
+  }
+};
+
+} // anonymous namespace
+
+void trans::removeZeroOutPropsInDeallocFinalize(MigrationPass &pass) {
+  ZeroOutInDeallocRemover trans(pass);
+  trans.TraverseDecl(pass.Ctx.getTranslationUnitDecl());
+}