457 lines
14 KiB
C++
457 lines
14 KiB
C++
//===--- 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;
|
|
std::unique_ptr<ParentMap> StmtMap;
|
|
|
|
Selector DelegateSel, FinalizeSel;
|
|
|
|
public:
|
|
RetainReleaseDeallocRemover(MigrationPass &pass)
|
|
: Body(nullptr), 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 their 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.
|
|
LLVM_FALLTHROUGH;
|
|
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);
|
|
Pass.TA.insertAfterToken(RecRange.getEnd(), str);
|
|
return true;
|
|
}
|
|
|
|
if (hasSideEffects(rec, Pass.Ctx) || !tryRemoving(RecContainer))
|
|
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) {
|
|
return isPlusOneAssignBeforeOrAfterAutorelease(E) ||
|
|
isReturnedAfterAutorelease(E);
|
|
}
|
|
|
|
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;
|
|
std::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)) {
|
|
return (RefD == getReferencedDecl(Bop->getLHS())) && isPlusOneAssign(Bop);
|
|
}
|
|
|
|
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 = nullptr, *nextStmt = nullptr;
|
|
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 nullptr;
|
|
|
|
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 nullptr;
|
|
}
|
|
}
|
|
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 nullptr;
|
|
}
|
|
|
|
/// \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 = nullptr;
|
|
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.begin() == StmtExprChild.end())
|
|
return;
|
|
auto *CompS = dyn_cast_or_null<CompoundStmt>(*StmtExprChild.begin());
|
|
if (!CompS)
|
|
return;
|
|
|
|
Stmt::child_range CompStmtChild = CompS->children();
|
|
if (CompStmtChild.begin() == CompStmtChild.end())
|
|
return;
|
|
auto *DeclS = dyn_cast_or_null<DeclStmt>(*CompStmtChild.begin());
|
|
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());
|
|
}
|