From 611ba3ea3300b71eb95dc4e45f20eee5dddd32e1 Mon Sep 17 00:00:00 2001
From: dim <dim@FreeBSD.org>
Date: Sun, 17 Jul 2011 15:40:56 +0000
Subject: Vendor import of clang trunk r135360:
http://llvm.org/svn/llvm-project/cfe/trunk@135360
---
lib/ARCMigrate/TransBlockObjCVariable.cpp | 143 ++++++++++++++++++++++++++++++
1 file changed, 143 insertions(+)
create mode 100644 lib/ARCMigrate/TransBlockObjCVariable.cpp
(limited to 'lib/ARCMigrate/TransBlockObjCVariable.cpp')
diff --git a/lib/ARCMigrate/TransBlockObjCVariable.cpp b/lib/ARCMigrate/TransBlockObjCVariable.cpp
new file mode 100644
index 0000000..0e342b7
--- /dev/null
+++ b/lib/ARCMigrate/TransBlockObjCVariable.cpp
@@ -0,0 +1,143 @@
+//===--- TransBlockObjCVariable.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.
+//
+//===----------------------------------------------------------------------===//
+//
+// rewriteBlockObjCVariable:
+//
+// Adding __block to an obj-c variable could be either because the the variable
+// is used for output storage or the user wanted to break a retain cycle.
+// This transformation checks whether a reference of the variable for the block
+// is actually needed (it is assigned to or its address is taken) or not.
+// If the reference is not needed it will assume __block was added to break a
+// cycle so it will remove '__block' and add __weak/__unsafe_unretained.
+// e.g
+//
+// __block Foo *x;
+// bar(^ { [x cake]; });
+// ---->
+// __weak Foo *x;
+// bar(^ { [x cake]; });
+//
+//===----------------------------------------------------------------------===//
+
+#include "Transforms.h"
+#include "Internals.h"
+#include "clang/Basic/SourceManager.h"
+
+using namespace clang;
+using namespace arcmt;
+using namespace trans;
+using llvm::StringRef;
+
+namespace {
+
+class RootBlockObjCVarRewriter :
+ public RecursiveASTVisitor<RootBlockObjCVarRewriter> {
+ MigrationPass &Pass;
+ llvm::DenseSet<VarDecl *> CheckedVars;
+
+ class BlockVarChecker : public RecursiveASTVisitor<BlockVarChecker> {
+ VarDecl *Var;
+
+ typedef RecursiveASTVisitor<BlockVarChecker> base;
+ public:
+ BlockVarChecker(VarDecl *var) : Var(var) { }
+
+ bool TraverseImplicitCastExpr(ImplicitCastExpr *castE) {
+ if (BlockDeclRefExpr *
+ ref = dyn_cast<BlockDeclRefExpr>(castE->getSubExpr())) {
+ if (ref->getDecl() == Var) {
+ if (castE->getCastKind() == CK_LValueToRValue)
+ return true; // Using the value of the variable.
+ if (castE->getCastKind() == CK_NoOp && castE->isLValue() &&
+ Var->getASTContext().getLangOptions().CPlusPlus)
+ return true; // Binding to const C++ reference.
+ }
+ }
+
+ return base::TraverseImplicitCastExpr(castE);
+ }
+
+ bool VisitBlockDeclRefExpr(BlockDeclRefExpr *E) {
+ if (E->getDecl() == Var)
+ return false; // The reference of the variable, and not just its value,
+ // is needed.
+ return true;
+ }
+ };
+
+public:
+ RootBlockObjCVarRewriter(MigrationPass &pass) : Pass(pass) { }
+
+ bool VisitBlockDecl(BlockDecl *block) {
+ llvm::SmallVector<VarDecl *, 4> BlockVars;
+
+ for (BlockDecl::capture_iterator
+ I = block->capture_begin(), E = block->capture_end(); I != E; ++I) {
+ VarDecl *var = I->getVariable();
+ if (I->isByRef() &&
+ !isAlreadyChecked(var) &&
+ var->getType()->isObjCObjectPointerType() &&
+ isImplicitStrong(var->getType())) {
+ BlockVars.push_back(var);
+ }
+ }
+
+ for (unsigned i = 0, e = BlockVars.size(); i != e; ++i) {
+ VarDecl *var = BlockVars[i];
+ CheckedVars.insert(var);
+
+ BlockVarChecker checker(var);
+ bool onlyValueOfVarIsNeeded = checker.TraverseStmt(block->getBody());
+ if (onlyValueOfVarIsNeeded) {
+ BlocksAttr *attr = var->getAttr<BlocksAttr>();
+ if(!attr)
+ continue;
+ bool useWeak = canApplyWeak(Pass.Ctx, var->getType());
+ SourceManager &SM = Pass.Ctx.getSourceManager();
+ Transaction Trans(Pass.TA);
+ Pass.TA.replaceText(SM.getInstantiationLoc(attr->getLocation()),
+ "__block",
+ useWeak ? "__weak" : "__unsafe_unretained");
+ }
+
+ }
+
+ return true;
+ }
+
+private:
+ bool isAlreadyChecked(VarDecl *VD) {
+ return CheckedVars.count(VD);
+ }
+
+ bool isImplicitStrong(QualType ty) {
+ if (isa<AttributedType>(ty.getTypePtr()))
+ return false;
+ return ty.getLocalQualifiers().getObjCLifetime() == Qualifiers::OCL_Strong;
+ }
+};
+
+class BlockObjCVarRewriter : public RecursiveASTVisitor<BlockObjCVarRewriter> {
+ MigrationPass &Pass;
+
+public:
+ BlockObjCVarRewriter(MigrationPass &pass) : Pass(pass) { }
+
+ bool TraverseBlockDecl(BlockDecl *block) {
+ RootBlockObjCVarRewriter(Pass).TraverseDecl(block);
+ return true;
+ }
+};
+
+} // anonymous namespace
+
+void trans::rewriteBlockObjCVariable(MigrationPass &pass) {
+ BlockObjCVarRewriter trans(pass);
+ trans.TraverseDecl(pass.Ctx.getTranslationUnitDecl());
+}
--
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