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//===--- TransRetainReleaseDealloc.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.
//
//===----------------------------------------------------------------------===//
//
// removeRetainReleaseDealloc:
//
// Removes retain/release/autorelease/dealloc messages.
//
// return [[foo retain] autorelease];
// ---->
// return foo;
//
//===----------------------------------------------------------------------===//
#include "Transforms.h"
#include "Internals.h"
#include "clang/Sema/SemaDiagnostic.h"
#include "clang/AST/ParentMap.h"
using namespace clang;
using namespace arcmt;
using namespace trans;
using llvm::StringRef;
namespace {
class RetainReleaseDeallocRemover :
public RecursiveASTVisitor<RetainReleaseDeallocRemover> {
Stmt *Body;
MigrationPass &Pass;
ExprSet Removables;
llvm::OwningPtr<ParentMap> StmtMap;
public:
RetainReleaseDeallocRemover(MigrationPass &pass)
: Body(0), Pass(pass) { }
void transformBody(Stmt *body) {
Body = body;
collectRemovables(body, Removables);
StmtMap.reset(new ParentMap(body));
TraverseStmt(body);
}
bool VisitObjCMessageExpr(ObjCMessageExpr *E) {
switch (E->getMethodFamily()) {
default:
return true;
case OMF_autorelease:
if (isRemovable(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.
std::string err = "it is not safe to remove an unused '";
err += E->getSelector().getAsString() + "'; its receiver may be "
"destroyed immediately";
Pass.TA.reportError(err, 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;
}
}
case OMF_dealloc:
break;
}
switch (E->getReceiverKind()) {
default:
return true;
case ObjCMessageExpr::SuperInstance: {
Transaction Trans(Pass.TA);
Pass.TA.clearDiagnostic(diag::err_arc_illegal_explicit_message,
diag::err_unavailable,
diag::err_unavailable_message,
E->getSuperLoc());
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);
Pass.TA.clearDiagnostic(diag::err_arc_illegal_explicit_message,
diag::err_unavailable,
diag::err_unavailable_message,
rec->getExprLoc());
if (!hasSideEffects(E, Pass.Ctx)) {
if (tryRemoving(E))
return true;
}
Pass.TA.replace(E->getSourceRange(), rec->getSourceRange());
return true;
}
private:
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::removeRetainReleaseDealloc(MigrationPass &pass) {
BodyTransform<RetainReleaseDeallocRemover> trans(pass);
trans.TraverseDecl(pass.Ctx.getTranslationUnitDecl());
}
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