1 files changed, 465 insertions, 0 deletions
diff --git a/contrib/llvm/tools/clang/lib/ARCMigrate/TransRetainReleaseDealloc.cpp b/contrib/llvm/tools/clang/lib/ARCMigrate/TransRetainReleaseDealloc.cpp
new file mode 100644
index 0000000..446a284
--- /dev/null
+++ b/contrib/llvm/tools/clang/lib/ARCMigrate/TransRetainReleaseDealloc.cpp
@@ -0,0 +1,465 @@
+//===--- TransRetainReleaseDealloc.cpp - Transformations to ARC mode ------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// removeRetainReleaseDealloc:
+//
+// Removes retain/release/autorelease/dealloc messages.
+//
+//  return [[foo retain] autorelease];
+// ---->
+//  return foo;
+//
+//===----------------------------------------------------------------------===//
+
+#include "Transforms.h"
+#include "Internals.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/ParentMap.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Lex/Lexer.h"
+#include "clang/Sema/SemaDiagnostic.h"
+#include "llvm/ADT/StringSwitch.h"
+
+using namespace clang;
+using namespace arcmt;
+using namespace trans;
+
+namespace {
+
+class RetainReleaseDeallocRemover :
+                       public RecursiveASTVisitor<RetainReleaseDeallocRemover> {
+  Stmt *Body;
+  MigrationPass &Pass;
+
+  ExprSet Removables;
+  OwningPtr<ParentMap> StmtMap;
+
+  Selector DelegateSel, FinalizeSel;
+
+public:
+  RetainReleaseDeallocRemover(MigrationPass &pass)
+    : Body(0), Pass(pass) {
+    DelegateSel =
+        Pass.Ctx.Selectors.getNullarySelector(&Pass.Ctx.Idents.get("delegate"));
+    FinalizeSel =
+        Pass.Ctx.Selectors.getNullarySelector(&Pass.Ctx.Idents.get("finalize"));
+  }
+
+  void transformBody(Stmt *body, Decl *ParentD) {
+    Body = body;
+    collectRemovables(body, Removables);
+    StmtMap.reset(new ParentMap(body));
+    TraverseStmt(body);
+  }
+
+  bool VisitObjCMessageExpr(ObjCMessageExpr *E) {
+    switch (E->getMethodFamily()) {
+    default:
+      if (E->isInstanceMessage() && E->getSelector() == FinalizeSel)
+        break;
+      return true;
+    case OMF_autorelease:
+      if (isRemovable(E)) {
+        if (!isCommonUnusedAutorelease(E)) {
+          // An unused autorelease is badness. If we remove it the receiver
+          // will likely die immediately while previously it was kept alive
+          // by the autorelease pool. This is bad practice in general, leave it
+          // and emit an error to force the user to restructure his code.
+          Pass.TA.reportError("it is not safe to remove an unused 'autorelease' "
+              "message; its receiver may be destroyed immediately",
+              E->getLocStart(), E->getSourceRange());
+          return true;
+        }
+      }
+      // Pass through.
+    case OMF_retain:
+    case OMF_release:
+      if (E->getReceiverKind() == ObjCMessageExpr::Instance)
+        if (Expr *rec = E->getInstanceReceiver()) {
+          rec = rec->IgnoreParenImpCasts();
+          if (rec->getType().getObjCLifetime() == Qualifiers::OCL_ExplicitNone &&
+              (E->getMethodFamily() != OMF_retain || isRemovable(E))) {
+            std::string err = "it is not safe to remove '";
+            err += E->getSelector().getAsString() + "' message on "
+                "an __unsafe_unretained type";
+            Pass.TA.reportError(err, rec->getLocStart());
+            return true;
+          }
+
+          if (isGlobalVar(rec) &&
+              (E->getMethodFamily() != OMF_retain || isRemovable(E))) {
+            std::string err = "it is not safe to remove '";
+            err += E->getSelector().getAsString() + "' message on "
+                "a global variable";
+            Pass.TA.reportError(err, rec->getLocStart());
+            return true;
+          }
+
+          if (E->getMethodFamily() == OMF_release && isDelegateMessage(rec)) {
+            Pass.TA.reportError("it is not safe to remove 'retain' "
+                "message on the result of a 'delegate' message; "
+                "the object that was passed to 'setDelegate:' may not be "
+                "properly retained", rec->getLocStart());
+            return true;
+          }
+        }
+    case OMF_dealloc:
+      break;
+    }
+
+    switch (E->getReceiverKind()) {
+    default:
+      return true;
+    case ObjCMessageExpr::SuperInstance: {
+      Transaction Trans(Pass.TA);
+      clearDiagnostics(E->getSelectorLoc(0));
+      if (tryRemoving(E))
+        return true;
+      Pass.TA.replace(E->getSourceRange(), "self");
+      return true;
+    }
+    case ObjCMessageExpr::Instance:
+      break;
+    }
+
+    Expr *rec = E->getInstanceReceiver();
+    if (!rec) return true;
+
+    Transaction Trans(Pass.TA);
+    clearDiagnostics(E->getSelectorLoc(0));
+
+    ObjCMessageExpr *Msg = E;
+    Expr *RecContainer = Msg;
+    SourceRange RecRange = rec->getSourceRange();
+    checkForGCDOrXPC(Msg, RecContainer, rec, RecRange);
+
+    if (Msg->getMethodFamily() == OMF_release &&
+        isRemovable(RecContainer) && isInAtFinally(RecContainer)) {
+      // Change the -release to "receiver = nil" in a finally to avoid a leak
+      // when an exception is thrown.
+      Pass.TA.replace(RecContainer->getSourceRange(), RecRange);
+      std::string str = " = ";
+      str += getNilString(Pass.Ctx);
+      Pass.TA.insertAfterToken(RecRange.getEnd(), str);
+      return true;
+    }
+
+    if (!hasSideEffects(rec, Pass.Ctx)) {
+      if (tryRemoving(RecContainer))
+        return true;
+    }
+    Pass.TA.replace(RecContainer->getSourceRange(), RecRange);
+
+    return true;
+  }
+
+private:
+  /// \brief Checks for idioms where an unused -autorelease is common.
+  ///
+  /// Returns true for this idiom which is common in property
+  /// setters:
+  ///
+  ///   [backingValue autorelease];
+  ///   backingValue = [newValue retain]; // in general a +1 assign
+  ///
+  /// For these as well:
+  ///
+  ///   [[var retain] autorelease];
+  ///   return var;
+  ///
+  bool isCommonUnusedAutorelease(ObjCMessageExpr *E) {
+    if (isPlusOneAssignBeforeOrAfterAutorelease(E))
+      return true;
+    if (isReturnedAfterAutorelease(E))
+      return true;
+    return false;
+  }
+
+  bool isReturnedAfterAutorelease(ObjCMessageExpr *E) {
+    Expr *Rec = E->getInstanceReceiver();
+    if (!Rec)
+      return false;
+
+    Decl *RefD = getReferencedDecl(Rec);
+    if (!RefD)
+      return false;
+
+    Stmt *nextStmt = getNextStmt(E);
+    if (!nextStmt)
+      return false;
+
+    // Check for "return <variable>;".
+
+    if (ReturnStmt *RetS = dyn_cast<ReturnStmt>(nextStmt))
+      return RefD == getReferencedDecl(RetS->getRetValue());
+
+    return false;
+  }
+
+  bool isPlusOneAssignBeforeOrAfterAutorelease(ObjCMessageExpr *E) {
+    Expr *Rec = E->getInstanceReceiver();
+    if (!Rec)
+      return false;
+
+    Decl *RefD = getReferencedDecl(Rec);
+    if (!RefD)
+      return false;
+
+    Stmt *prevStmt, *nextStmt;
+    llvm::tie(prevStmt, nextStmt) = getPreviousAndNextStmt(E);
+
+    return isPlusOneAssignToVar(prevStmt, RefD) ||
+           isPlusOneAssignToVar(nextStmt, RefD);
+  }
+
+  bool isPlusOneAssignToVar(Stmt *S, Decl *RefD) {
+    if (!S)
+      return false;
+
+    // Check for "RefD = [+1 retained object];".
+
+    if (BinaryOperator *Bop = dyn_cast<BinaryOperator>(S)) {
+      if (RefD != getReferencedDecl(Bop->getLHS()))
+        return false;
+      if (isPlusOneAssign(Bop))
+        return true;
+      return false;
+    }
+
+    if (DeclStmt *DS = dyn_cast<DeclStmt>(S)) {
+      if (DS->isSingleDecl() && DS->getSingleDecl() == RefD) {
+        if (VarDecl *VD = dyn_cast<VarDecl>(RefD))
+          return isPlusOne(VD->getInit());
+      }
+      return false;
+    }
+
+    return false;
+  }
+
+  Stmt *getNextStmt(Expr *E) {
+    return getPreviousAndNextStmt(E).second;
+  }
+
+  std::pair<Stmt *, Stmt *> getPreviousAndNextStmt(Expr *E) {
+    Stmt *prevStmt = 0, *nextStmt = 0;
+    if (!E)
+      return std::make_pair(prevStmt, nextStmt);
+
+    Stmt *OuterS = E, *InnerS;
+    do {
+      InnerS = OuterS;
+      OuterS = StmtMap->getParent(InnerS);
+    }
+    while (OuterS && (isa<ParenExpr>(OuterS) ||
+                      isa<CastExpr>(OuterS) ||
+                      isa<ExprWithCleanups>(OuterS)));
+    
+    if (!OuterS)
+      return std::make_pair(prevStmt, nextStmt);
+
+    Stmt::child_iterator currChildS = OuterS->child_begin();
+    Stmt::child_iterator childE = OuterS->child_end();
+    Stmt::child_iterator prevChildS = childE;
+    for (; currChildS != childE; ++currChildS) {
+      if (*currChildS == InnerS)
+        break;
+      prevChildS = currChildS;
+    }
+
+    if (prevChildS != childE) {
+      prevStmt = *prevChildS;
+      if (prevStmt)
+        prevStmt = prevStmt->IgnoreImplicit();
+    }
+
+    if (currChildS == childE)
+      return std::make_pair(prevStmt, nextStmt);
+    ++currChildS;
+    if (currChildS == childE)
+      return std::make_pair(prevStmt, nextStmt);
+
+    nextStmt = *currChildS;
+    if (nextStmt)
+      nextStmt = nextStmt->IgnoreImplicit();
+
+    return std::make_pair(prevStmt, nextStmt);
+  }
+
+  Decl *getReferencedDecl(Expr *E) {
+    if (!E)
+      return 0;
+
+    E = E->IgnoreParenCasts();
+    if (ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E)) {
+      switch (ME->getMethodFamily()) {
+      case OMF_copy:
+      case OMF_autorelease:
+      case OMF_release:
+      case OMF_retain:
+        return getReferencedDecl(ME->getInstanceReceiver());
+      default:
+        return 0;
+      }
+    }
+    if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
+      return DRE->getDecl();
+    if (MemberExpr *ME = dyn_cast<MemberExpr>(E))
+      return ME->getMemberDecl();
+    if (ObjCIvarRefExpr *IRE = dyn_cast<ObjCIvarRefExpr>(E))
+      return IRE->getDecl();
+
+    return 0;
+  }
+
+  /// \brief Check if the retain/release is due to a GCD/XPC macro that are
+  /// defined as:
+  ///
+  /// #define dispatch_retain(object) ({ dispatch_object_t _o = (object); _dispatch_object_validate(_o); (void)[_o retain]; })
+  /// #define dispatch_release(object) ({ dispatch_object_t _o = (object); _dispatch_object_validate(_o); [_o release]; })
+  /// #define xpc_retain(object) ({ xpc_object_t _o = (object); _xpc_object_validate(_o); [_o retain]; })
+  /// #define xpc_release(object) ({ xpc_object_t _o = (object); _xpc_object_validate(_o); [_o release]; })
+  ///
+  /// and return the top container which is the StmtExpr and the macro argument
+  /// expression.
+  void checkForGCDOrXPC(ObjCMessageExpr *Msg, Expr *&RecContainer,
+                        Expr *&Rec, SourceRange &RecRange) {
+    SourceLocation Loc = Msg->getExprLoc();
+    if (!Loc.isMacroID())
+      return;
+    SourceManager &SM = Pass.Ctx.getSourceManager();
+    StringRef MacroName = Lexer::getImmediateMacroName(Loc, SM,
+                                                     Pass.Ctx.getLangOpts());
+    bool isGCDOrXPC = llvm::StringSwitch<bool>(MacroName)
+        .Case("dispatch_retain", true)
+        .Case("dispatch_release", true)
+        .Case("xpc_retain", true)
+        .Case("xpc_release", true)
+        .Default(false);
+    if (!isGCDOrXPC)
+      return;
+
+    StmtExpr *StmtE = 0;
+    Stmt *S = Msg;
+    while (S) {
+      if (StmtExpr *SE = dyn_cast<StmtExpr>(S)) {
+        StmtE = SE;
+        break;
+      }
+      S = StmtMap->getParent(S);
+    }
+
+    if (!StmtE)
+      return;
+
+    Stmt::child_range StmtExprChild = StmtE->children();
+    if (!StmtExprChild)
+      return;
+    CompoundStmt *CompS = dyn_cast_or_null<CompoundStmt>(*StmtExprChild);
+    if (!CompS)
+      return;
+
+    Stmt::child_range CompStmtChild = CompS->children();
+    if (!CompStmtChild)
+      return;
+    DeclStmt *DeclS = dyn_cast_or_null<DeclStmt>(*CompStmtChild);
+    if (!DeclS)
+      return;
+    if (!DeclS->isSingleDecl())
+      return;
+    VarDecl *VD = dyn_cast_or_null<VarDecl>(DeclS->getSingleDecl());
+    if (!VD)
+      return;
+    Expr *Init = VD->getInit();
+    if (!Init)
+      return;
+
+    RecContainer = StmtE;
+    Rec = Init->IgnoreParenImpCasts();
+    if (ExprWithCleanups *EWC = dyn_cast<ExprWithCleanups>(Rec))
+      Rec = EWC->getSubExpr()->IgnoreParenImpCasts();
+    RecRange = Rec->getSourceRange();
+    if (SM.isMacroArgExpansion(RecRange.getBegin()))
+      RecRange.setBegin(SM.getImmediateSpellingLoc(RecRange.getBegin()));
+    if (SM.isMacroArgExpansion(RecRange.getEnd()))
+      RecRange.setEnd(SM.getImmediateSpellingLoc(RecRange.getEnd()));
+  }
+
+  void clearDiagnostics(SourceLocation loc) const {
+    Pass.TA.clearDiagnostic(diag::err_arc_illegal_explicit_message,
+                            diag::err_unavailable,
+                            diag::err_unavailable_message,
+                            loc);
+  }
+
+  bool isDelegateMessage(Expr *E) const {
+    if (!E) return false;
+
+    E = E->IgnoreParenCasts();
+
+    // Also look through property-getter sugar.
+    if (PseudoObjectExpr *pseudoOp = dyn_cast<PseudoObjectExpr>(E))
+      E = pseudoOp->getResultExpr()->IgnoreImplicit();
+
+    if (ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E))
+      return (ME->isInstanceMessage() && ME->getSelector() == DelegateSel);
+
+    return false;
+  }
+
+  bool isInAtFinally(Expr *E) const {
+    assert(E);
+    Stmt *S = E;
+    while (S) {
+      if (isa<ObjCAtFinallyStmt>(S))
+        return true;
+      S = StmtMap->getParent(S);
+    }
+
+    return false;
+  }
+
+  bool isRemovable(Expr *E) const {
+    return Removables.count(E);
+  }
+  
+  bool tryRemoving(Expr *E) const {
+    if (isRemovable(E)) {
+      Pass.TA.removeStmt(E);
+      return true;
+    }
+
+    Stmt *parent = StmtMap->getParent(E);
+
+    if (ImplicitCastExpr *castE = dyn_cast_or_null<ImplicitCastExpr>(parent))
+      return tryRemoving(castE);
+
+    if (ParenExpr *parenE = dyn_cast_or_null<ParenExpr>(parent))
+      return tryRemoving(parenE);
+
+    if (BinaryOperator *
+          bopE = dyn_cast_or_null<BinaryOperator>(parent)) {
+      if (bopE->getOpcode() == BO_Comma && bopE->getLHS() == E &&
+          isRemovable(bopE)) {
+        Pass.TA.replace(bopE->getSourceRange(), bopE->getRHS()->getSourceRange());
+        return true;
+      }
+    }
+
+    return false;
+  }
+
+};
+
+} // anonymous namespace
+
+void trans::removeRetainReleaseDeallocFinalize(MigrationPass &pass) {
+  BodyTransform<RetainReleaseDeallocRemover> trans(pass);
+  trans.TraverseDecl(pass.Ctx.getTranslationUnitDecl());
+}