1 //===--- TransAutoreleasePool.cpp - Transformations to ARC mode -----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // rewriteAutoreleasePool:
12 // Calls to NSAutoreleasePools will be rewritten as an @autorelease scope.
14 // NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
22 // An NSAutoreleasePool will not be touched if:
23 // - There is not a corresponding -release/-drain in the same scope
24 // - Not all references of the NSAutoreleasePool variable can be removed
25 // - There is a variable that is declared inside the intended @autorelease scope
26 // which is also used outside it.
28 //===----------------------------------------------------------------------===//
30 #include "Transforms.h"
31 #include "Internals.h"
32 #include "clang/AST/ASTContext.h"
33 #include "clang/Basic/SourceManager.h"
34 #include "clang/Sema/SemaDiagnostic.h"
37 using namespace clang;
38 using namespace arcmt;
39 using namespace trans;
43 class ReleaseCollector : public RecursiveASTVisitor<ReleaseCollector> {
45 SmallVectorImpl<ObjCMessageExpr *> &Releases;
48 ReleaseCollector(Decl *D, SmallVectorImpl<ObjCMessageExpr *> &releases)
49 : Dcl(D), Releases(releases) { }
51 bool VisitObjCMessageExpr(ObjCMessageExpr *E) {
52 if (!E->isInstanceMessage())
54 if (E->getMethodFamily() != OMF_release)
56 Expr *instance = E->getInstanceReceiver()->IgnoreParenCasts();
57 if (DeclRefExpr *DE = dyn_cast<DeclRefExpr>(instance)) {
58 if (DE->getDecl() == Dcl)
59 Releases.push_back(E);
69 class AutoreleasePoolRewriter
70 : public RecursiveASTVisitor<AutoreleasePoolRewriter> {
72 AutoreleasePoolRewriter(MigrationPass &pass)
73 : Body(0), Pass(pass) {
74 PoolII = &pass.Ctx.Idents.get("NSAutoreleasePool");
75 DrainSel = pass.Ctx.Selectors.getNullarySelector(
76 &pass.Ctx.Idents.get("drain"));
79 void transformBody(Stmt *body, Decl *ParentD) {
84 ~AutoreleasePoolRewriter() {
85 SmallVector<VarDecl *, 8> VarsToHandle;
87 for (std::map<VarDecl *, PoolVarInfo>::iterator
88 I = PoolVars.begin(), E = PoolVars.end(); I != E; ++I) {
89 VarDecl *var = I->first;
90 PoolVarInfo &info = I->second;
92 // Check that we can handle/rewrite all references of the pool.
94 clearRefsIn(info.Dcl, info.Refs);
95 for (SmallVectorImpl<PoolScope>::iterator
96 scpI = info.Scopes.begin(),
97 scpE = info.Scopes.end(); scpI != scpE; ++scpI) {
98 PoolScope &scope = *scpI;
99 clearRefsIn(*scope.Begin, info.Refs);
100 clearRefsIn(*scope.End, info.Refs);
101 clearRefsIn(scope.Releases.begin(), scope.Releases.end(), info.Refs);
104 // Even if one reference is not handled we will not do anything about that
106 if (info.Refs.empty())
107 VarsToHandle.push_back(var);
110 for (unsigned i = 0, e = VarsToHandle.size(); i != e; ++i) {
111 PoolVarInfo &info = PoolVars[VarsToHandle[i]];
113 Transaction Trans(Pass.TA);
115 clearUnavailableDiags(info.Dcl);
116 Pass.TA.removeStmt(info.Dcl);
118 // Add "@autoreleasepool { }"
119 for (SmallVectorImpl<PoolScope>::iterator
120 scpI = info.Scopes.begin(),
121 scpE = info.Scopes.end(); scpI != scpE; ++scpI) {
122 PoolScope &scope = *scpI;
123 clearUnavailableDiags(*scope.Begin);
124 clearUnavailableDiags(*scope.End);
125 if (scope.IsFollowedBySimpleReturnStmt) {
126 // Include the return in the scope.
127 Pass.TA.replaceStmt(*scope.Begin, "@autoreleasepool {");
128 Pass.TA.removeStmt(*scope.End);
129 Stmt::child_iterator retI = scope.End;
131 SourceLocation afterSemi = findLocationAfterSemi((*retI)->getLocEnd(),
133 assert(afterSemi.isValid() &&
134 "Didn't we check before setting IsFollowedBySimpleReturnStmt "
136 Pass.TA.insertAfterToken(afterSemi, "\n}");
137 Pass.TA.increaseIndentation(
138 SourceRange(scope.getIndentedRange().getBegin(),
139 (*retI)->getLocEnd()),
140 scope.CompoundParent->getLocStart());
142 Pass.TA.replaceStmt(*scope.Begin, "@autoreleasepool {");
143 Pass.TA.replaceStmt(*scope.End, "}");
144 Pass.TA.increaseIndentation(scope.getIndentedRange(),
145 scope.CompoundParent->getLocStart());
149 // Remove rest of pool var references.
150 for (SmallVectorImpl<PoolScope>::iterator
151 scpI = info.Scopes.begin(),
152 scpE = info.Scopes.end(); scpI != scpE; ++scpI) {
153 PoolScope &scope = *scpI;
154 for (SmallVectorImpl<ObjCMessageExpr *>::iterator
155 relI = scope.Releases.begin(),
156 relE = scope.Releases.end(); relI != relE; ++relI) {
157 clearUnavailableDiags(*relI);
158 Pass.TA.removeStmt(*relI);
164 bool VisitCompoundStmt(CompoundStmt *S) {
165 SmallVector<PoolScope, 4> Scopes;
167 for (Stmt::child_iterator
168 I = S->body_begin(), E = S->body_end(); I != E; ++I) {
169 Stmt *child = getEssential(*I);
170 if (DeclStmt *DclS = dyn_cast<DeclStmt>(child)) {
171 if (DclS->isSingleDecl()) {
172 if (VarDecl *VD = dyn_cast<VarDecl>(DclS->getSingleDecl())) {
173 if (isNSAutoreleasePool(VD->getType())) {
174 PoolVarInfo &info = PoolVars[VD];
176 collectRefs(VD, S, info.Refs);
177 // Does this statement follow the pattern:
178 // NSAutoreleasePool * pool = [NSAutoreleasePool new];
179 if (isPoolCreation(VD->getInit())) {
180 Scopes.push_back(PoolScope());
181 Scopes.back().PoolVar = VD;
182 Scopes.back().CompoundParent = S;
183 Scopes.back().Begin = I;
188 } else if (BinaryOperator *bop = dyn_cast<BinaryOperator>(child)) {
189 if (DeclRefExpr *dref = dyn_cast<DeclRefExpr>(bop->getLHS())) {
190 if (VarDecl *VD = dyn_cast<VarDecl>(dref->getDecl())) {
191 // Does this statement follow the pattern:
192 // pool = [NSAutoreleasePool new];
193 if (isNSAutoreleasePool(VD->getType()) &&
194 isPoolCreation(bop->getRHS())) {
195 Scopes.push_back(PoolScope());
196 Scopes.back().PoolVar = VD;
197 Scopes.back().CompoundParent = S;
198 Scopes.back().Begin = I;
207 if (isPoolDrain(Scopes.back().PoolVar, child)) {
208 PoolScope &scope = Scopes.back();
210 handlePoolScope(scope, S);
218 void clearUnavailableDiags(Stmt *S) {
220 Pass.TA.clearDiagnostic(diag::err_unavailable,
221 diag::err_unavailable_message,
222 S->getSourceRange());
227 CompoundStmt *CompoundParent;
228 Stmt::child_iterator Begin;
229 Stmt::child_iterator End;
230 bool IsFollowedBySimpleReturnStmt;
231 SmallVector<ObjCMessageExpr *, 4> Releases;
233 PoolScope() : PoolVar(0), CompoundParent(0), Begin(), End(),
234 IsFollowedBySimpleReturnStmt(false) { }
236 SourceRange getIndentedRange() const {
237 Stmt::child_iterator rangeS = Begin;
240 return SourceRange();
241 Stmt::child_iterator rangeE = Begin;
242 for (Stmt::child_iterator I = rangeS; I != End; ++I)
244 return SourceRange((*rangeS)->getLocStart(), (*rangeE)->getLocEnd());
248 class NameReferenceChecker : public RecursiveASTVisitor<NameReferenceChecker>{
250 SourceRange ScopeRange;
251 SourceLocation &referenceLoc, &declarationLoc;
254 NameReferenceChecker(ASTContext &ctx, PoolScope &scope,
255 SourceLocation &referenceLoc,
256 SourceLocation &declarationLoc)
257 : Ctx(ctx), referenceLoc(referenceLoc),
258 declarationLoc(declarationLoc) {
259 ScopeRange = SourceRange((*scope.Begin)->getLocStart(),
260 (*scope.End)->getLocStart());
263 bool VisitDeclRefExpr(DeclRefExpr *E) {
264 return checkRef(E->getLocation(), E->getDecl()->getLocation());
267 bool VisitTypedefTypeLoc(TypedefTypeLoc TL) {
268 return checkRef(TL.getBeginLoc(), TL.getTypedefNameDecl()->getLocation());
271 bool VisitTagTypeLoc(TagTypeLoc TL) {
272 return checkRef(TL.getBeginLoc(), TL.getDecl()->getLocation());
276 bool checkRef(SourceLocation refLoc, SourceLocation declLoc) {
277 if (isInScope(declLoc)) {
278 referenceLoc = refLoc;
279 declarationLoc = declLoc;
285 bool isInScope(SourceLocation loc) {
289 SourceManager &SM = Ctx.getSourceManager();
290 if (SM.isBeforeInTranslationUnit(loc, ScopeRange.getBegin()))
292 return SM.isBeforeInTranslationUnit(loc, ScopeRange.getEnd());
296 void handlePoolScope(PoolScope &scope, CompoundStmt *compoundS) {
297 // Check that all names declared inside the scope are not used
298 // outside the scope.
300 bool nameUsedOutsideScope = false;
301 SourceLocation referenceLoc, declarationLoc;
302 Stmt::child_iterator SI = scope.End, SE = compoundS->body_end();
304 // Check if the autoreleasepool scope is followed by a simple return
305 // statement, in which case we will include the return in the scope.
307 if (ReturnStmt *retS = dyn_cast<ReturnStmt>(*SI))
308 if ((retS->getRetValue() == 0 ||
309 isa<DeclRefExpr>(retS->getRetValue()->IgnoreParenCasts())) &&
310 findLocationAfterSemi(retS->getLocEnd(), Pass.Ctx).isValid()) {
311 scope.IsFollowedBySimpleReturnStmt = true;
312 ++SI; // the return will be included in scope, don't check it.
315 for (; SI != SE; ++SI) {
316 nameUsedOutsideScope = !NameReferenceChecker(Pass.Ctx, scope,
318 declarationLoc).TraverseStmt(*SI);
319 if (nameUsedOutsideScope)
323 // If not all references were cleared it means some variables/typenames/etc
324 // declared inside the pool scope are used outside of it.
325 // We won't try to rewrite the pool.
326 if (nameUsedOutsideScope) {
327 Pass.TA.reportError("a name is referenced outside the "
328 "NSAutoreleasePool scope that it was declared in", referenceLoc);
329 Pass.TA.reportNote("name declared here", declarationLoc);
330 Pass.TA.reportNote("intended @autoreleasepool scope begins here",
331 (*scope.Begin)->getLocStart());
332 Pass.TA.reportNote("intended @autoreleasepool scope ends here",
333 (*scope.End)->getLocStart());
338 // Collect all releases of the pool; they will be removed.
340 ReleaseCollector releaseColl(scope.PoolVar, scope.Releases);
341 Stmt::child_iterator I = scope.Begin;
343 for (; I != scope.End; ++I)
344 releaseColl.TraverseStmt(*I);
347 PoolVars[scope.PoolVar].Scopes.push_back(scope);
350 bool isPoolCreation(Expr *E) {
351 if (!E) return false;
353 ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E);
354 if (!ME) return false;
355 if (ME->getMethodFamily() == OMF_new &&
356 ME->getReceiverKind() == ObjCMessageExpr::Class &&
357 isNSAutoreleasePool(ME->getReceiverInterface()))
359 if (ME->getReceiverKind() == ObjCMessageExpr::Instance &&
360 ME->getMethodFamily() == OMF_init) {
361 Expr *rec = getEssential(ME->getInstanceReceiver());
362 if (ObjCMessageExpr *recME = dyn_cast_or_null<ObjCMessageExpr>(rec)) {
363 if (recME->getMethodFamily() == OMF_alloc &&
364 recME->getReceiverKind() == ObjCMessageExpr::Class &&
365 isNSAutoreleasePool(recME->getReceiverInterface()))
373 bool isPoolDrain(VarDecl *poolVar, Stmt *S) {
374 if (!S) return false;
376 ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(S);
377 if (!ME) return false;
378 if (ME->getReceiverKind() == ObjCMessageExpr::Instance) {
379 Expr *rec = getEssential(ME->getInstanceReceiver());
380 if (DeclRefExpr *dref = dyn_cast<DeclRefExpr>(rec))
381 if (dref->getDecl() == poolVar)
382 return ME->getMethodFamily() == OMF_release ||
383 ME->getSelector() == DrainSel;
389 bool isNSAutoreleasePool(ObjCInterfaceDecl *IDecl) {
390 return IDecl && IDecl->getIdentifier() == PoolII;
393 bool isNSAutoreleasePool(QualType Ty) {
394 QualType pointee = Ty->getPointeeType();
395 if (pointee.isNull())
397 if (const ObjCInterfaceType *interT = pointee->getAs<ObjCInterfaceType>())
398 return isNSAutoreleasePool(interT->getDecl());
402 static Expr *getEssential(Expr *E) {
403 return cast<Expr>(getEssential((Stmt*)E));
405 static Stmt *getEssential(Stmt *S) {
406 if (ExprWithCleanups *EWC = dyn_cast<ExprWithCleanups>(S))
407 S = EWC->getSubExpr();
408 if (Expr *E = dyn_cast<Expr>(S))
409 S = E->IgnoreParenCasts();
416 IdentifierInfo *PoolII;
422 SmallVector<PoolScope, 2> Scopes;
424 PoolVarInfo() : Dcl(0) { }
427 std::map<VarDecl *, PoolVarInfo> PoolVars;
430 } // anonymous namespace
432 void trans::rewriteAutoreleasePool(MigrationPass &pass) {
433 BodyTransform<AutoreleasePoolRewriter> trans(pass);
434 trans.TraverseDecl(pass.Ctx.getTranslationUnitDecl());