forked from OSchip/llvm-project
148 lines
4.5 KiB
C++
148 lines
4.5 KiB
C++
//===--- TransBlockObjCVariable.cpp - Transformations to ARC mode ---------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// rewriteBlockObjCVariable:
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//
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// Adding __block to an obj-c variable could be either because the variable
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// is used for output storage or the user wanted to break a retain cycle.
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// This transformation checks whether a reference of the variable for the block
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// is actually needed (it is assigned to or its address is taken) or not.
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// If the reference is not needed it will assume __block was added to break a
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// cycle so it will remove '__block' and add __weak/__unsafe_unretained.
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// e.g
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//
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// __block Foo *x;
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// bar(^ { [x cake]; });
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// ---->
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// __weak Foo *x;
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// bar(^ { [x cake]; });
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//
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//===----------------------------------------------------------------------===//
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#include "Transforms.h"
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#include "Internals.h"
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#include "clang/AST/ASTContext.h"
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#include "clang/AST/Attr.h"
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#include "clang/Basic/SourceManager.h"
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using namespace clang;
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using namespace arcmt;
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using namespace trans;
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namespace {
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class RootBlockObjCVarRewriter :
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public RecursiveASTVisitor<RootBlockObjCVarRewriter> {
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llvm::DenseSet<VarDecl *> &VarsToChange;
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class BlockVarChecker : public RecursiveASTVisitor<BlockVarChecker> {
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VarDecl *Var;
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typedef RecursiveASTVisitor<BlockVarChecker> base;
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public:
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BlockVarChecker(VarDecl *var) : Var(var) { }
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bool TraverseImplicitCastExpr(ImplicitCastExpr *castE) {
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if (DeclRefExpr *
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ref = dyn_cast<DeclRefExpr>(castE->getSubExpr())) {
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if (ref->getDecl() == Var) {
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if (castE->getCastKind() == CK_LValueToRValue)
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return true; // Using the value of the variable.
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if (castE->getCastKind() == CK_NoOp && castE->isLValue() &&
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Var->getASTContext().getLangOpts().CPlusPlus)
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return true; // Binding to const C++ reference.
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}
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}
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return base::TraverseImplicitCastExpr(castE);
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}
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bool VisitDeclRefExpr(DeclRefExpr *E) {
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if (E->getDecl() == Var)
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return false; // The reference of the variable, and not just its value,
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// is needed.
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return true;
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}
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};
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public:
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RootBlockObjCVarRewriter(llvm::DenseSet<VarDecl *> &VarsToChange)
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: VarsToChange(VarsToChange) { }
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bool VisitBlockDecl(BlockDecl *block) {
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SmallVector<VarDecl *, 4> BlockVars;
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for (const auto &I : block->captures()) {
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VarDecl *var = I.getVariable();
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if (I.isByRef() &&
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var->getType()->isObjCObjectPointerType() &&
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isImplicitStrong(var->getType())) {
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BlockVars.push_back(var);
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}
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}
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for (unsigned i = 0, e = BlockVars.size(); i != e; ++i) {
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VarDecl *var = BlockVars[i];
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BlockVarChecker checker(var);
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bool onlyValueOfVarIsNeeded = checker.TraverseStmt(block->getBody());
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if (onlyValueOfVarIsNeeded)
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VarsToChange.insert(var);
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else
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VarsToChange.erase(var);
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}
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return true;
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}
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private:
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bool isImplicitStrong(QualType ty) {
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if (isa<AttributedType>(ty.getTypePtr()))
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return false;
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return ty.getLocalQualifiers().getObjCLifetime() == Qualifiers::OCL_Strong;
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}
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};
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class BlockObjCVarRewriter : public RecursiveASTVisitor<BlockObjCVarRewriter> {
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llvm::DenseSet<VarDecl *> &VarsToChange;
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public:
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BlockObjCVarRewriter(llvm::DenseSet<VarDecl *> &VarsToChange)
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: VarsToChange(VarsToChange) { }
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bool TraverseBlockDecl(BlockDecl *block) {
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RootBlockObjCVarRewriter(VarsToChange).TraverseDecl(block);
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return true;
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}
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};
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} // anonymous namespace
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void BlockObjCVariableTraverser::traverseBody(BodyContext &BodyCtx) {
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MigrationPass &Pass = BodyCtx.getMigrationContext().Pass;
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llvm::DenseSet<VarDecl *> VarsToChange;
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BlockObjCVarRewriter trans(VarsToChange);
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trans.TraverseStmt(BodyCtx.getTopStmt());
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for (llvm::DenseSet<VarDecl *>::iterator
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I = VarsToChange.begin(), E = VarsToChange.end(); I != E; ++I) {
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VarDecl *var = *I;
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BlocksAttr *attr = var->getAttr<BlocksAttr>();
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if(!attr)
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continue;
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bool useWeak = canApplyWeak(Pass.Ctx, var->getType());
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SourceManager &SM = Pass.Ctx.getSourceManager();
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Transaction Trans(Pass.TA);
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Pass.TA.replaceText(SM.getExpansionLoc(attr->getLocation()),
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"__block",
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useWeak ? "__weak" : "__unsafe_unretained");
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}
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}
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