Transforms.cpp revision a64ccefdf0ea4e03ec88805d71b0af74950c7472 
1//===--- Tranforms.cpp - Tranformations to ARC mode -----------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#include "Transforms.h"
11#include "Internals.h"
12#include "clang/Sema/SemaDiagnostic.h"
13#include "clang/AST/RecursiveASTVisitor.h"
14#include "clang/AST/StmtVisitor.h"
15#include "clang/AST/ParentMap.h"
16#include "clang/Analysis/DomainSpecific/CocoaConventions.h"
17#include "clang/Lex/Lexer.h"
18#include "clang/Basic/SourceManager.h"
19#include "llvm/ADT/StringSwitch.h"
20#include "llvm/ADT/DenseSet.h"
21#include <map>
22
23using namespace clang;
24using namespace arcmt;
25using namespace trans;
26
27//===----------------------------------------------------------------------===//
28// Helpers.
29//===----------------------------------------------------------------------===//
30
31/// \brief True if the class is one that does not support weak.
32static bool isClassInWeakBlacklist(ObjCInterfaceDecl *cls) {
33  if (!cls)
34    return false;
35
36  bool inList = llvm::StringSwitch<bool>(cls->getName())
37                 .Case("NSColorSpace", true)
38                 .Case("NSFont", true)
39                 .Case("NSFontPanel", true)
40                 .Case("NSImage", true)
41                 .Case("NSLazyBrowserCell", true)
42                 .Case("NSWindow", true)
43                 .Case("NSWindowController", true)
44                 .Case("NSMenuView", true)
45                 .Case("NSPersistentUIWindowInfo", true)
46                 .Case("NSTableCellView", true)
47                 .Case("NSATSTypeSetter", true)
48                 .Case("NSATSGlyphStorage", true)
49                 .Case("NSLineFragmentRenderingContext", true)
50                 .Case("NSAttributeDictionary", true)
51                 .Case("NSParagraphStyle", true)
52                 .Case("NSTextTab", true)
53                 .Case("NSSimpleHorizontalTypesetter", true)
54                 .Case("_NSCachedAttributedString", true)
55                 .Case("NSStringDrawingTextStorage", true)
56                 .Case("NSTextView", true)
57                 .Case("NSSubTextStorage", true)
58                 .Default(false);
59
60  if (inList)
61    return true;
62
63  return isClassInWeakBlacklist(cls->getSuperClass());
64}
65
66bool trans::canApplyWeak(ASTContext &Ctx, QualType type) {
67  if (!Ctx.getLangOptions().ObjCRuntimeHasWeak)
68    return false;
69
70  QualType T = type;
71  while (const PointerType *ptr = T->getAs<PointerType>())
72    T = ptr->getPointeeType();
73  if (const ObjCObjectPointerType *ObjT = T->getAs<ObjCObjectPointerType>()) {
74    ObjCInterfaceDecl *Class = ObjT->getInterfaceDecl();
75    if (!Class || Class->getName() == "NSObject")
76      return false; // id/NSObject is not safe for weak.
77    if (Class->isForwardDecl())
78      return false; // forward classes are not verifiable, therefore not safe.
79    if (Class->isArcWeakrefUnavailable())
80      return false;
81    if (isClassInWeakBlacklist(Class))
82      return false;
83  }
84
85  return true;
86}
87
88/// \brief 'Loc' is the end of a statement range. This returns the location
89/// immediately after the semicolon following the statement.
90/// If no semicolon is found or the location is inside a macro, the returned
91/// source location will be invalid.
92SourceLocation trans::findLocationAfterSemi(SourceLocation loc,
93                                            ASTContext &Ctx) {
94  SourceLocation SemiLoc = findSemiAfterLocation(loc, Ctx);
95  if (SemiLoc.isInvalid())
96    return SourceLocation();
97  return SemiLoc.getLocWithOffset(1);
98}
99
100/// \brief \arg Loc is the end of a statement range. This returns the location
101/// of the semicolon following the statement.
102/// If no semicolon is found or the location is inside a macro, the returned
103/// source location will be invalid.
104SourceLocation trans::findSemiAfterLocation(SourceLocation loc,
105                                            ASTContext &Ctx) {
106  SourceManager &SM = Ctx.getSourceManager();
107  if (loc.isMacroID()) {
108    if (!Lexer::isAtEndOfMacroExpansion(loc, SM, Ctx.getLangOptions()))
109      return SourceLocation();
110    loc = SM.getExpansionRange(loc).second;
111  }
112  loc = Lexer::getLocForEndOfToken(loc, /*Offset=*/0, SM, Ctx.getLangOptions());
113
114  // Break down the source location.
115  std::pair<FileID, unsigned> locInfo = SM.getDecomposedLoc(loc);
116
117  // Try to load the file buffer.
118  bool invalidTemp = false;
119  StringRef file = SM.getBufferData(locInfo.first, &invalidTemp);
120  if (invalidTemp)
121    return SourceLocation();
122
123  const char *tokenBegin = file.data() + locInfo.second;
124
125  // Lex from the start of the given location.
126  Lexer lexer(SM.getLocForStartOfFile(locInfo.first),
127              Ctx.getLangOptions(),
128              file.begin(), tokenBegin, file.end());
129  Token tok;
130  lexer.LexFromRawLexer(tok);
131  if (tok.isNot(tok::semi))
132    return SourceLocation();
133
134  return tok.getLocation();
135}
136
137bool trans::hasSideEffects(Expr *E, ASTContext &Ctx) {
138  if (!E || !E->HasSideEffects(Ctx))
139    return false;
140
141  E = E->IgnoreParenCasts();
142  ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(E);
143  if (!ME)
144    return true;
145  switch (ME->getMethodFamily()) {
146  case OMF_autorelease:
147  case OMF_dealloc:
148  case OMF_release:
149  case OMF_retain:
150    switch (ME->getReceiverKind()) {
151    case ObjCMessageExpr::SuperInstance:
152      return false;
153    case ObjCMessageExpr::Instance:
154      return hasSideEffects(ME->getInstanceReceiver(), Ctx);
155    default:
156      break;
157    }
158    break;
159  default:
160    break;
161  }
162
163  return true;
164}
165
166bool trans::isGlobalVar(Expr *E) {
167  E = E->IgnoreParenCasts();
168  if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
169    return DRE->getDecl()->getDeclContext()->isFileContext() &&
170           DRE->getDecl()->getLinkage() == ExternalLinkage;
171  if (ConditionalOperator *condOp = dyn_cast<ConditionalOperator>(E))
172    return isGlobalVar(condOp->getTrueExpr()) &&
173           isGlobalVar(condOp->getFalseExpr());
174
175  return false;
176}
177
178StringRef trans::getNilString(ASTContext &Ctx) {
179  if (Ctx.Idents.get("nil").hasMacroDefinition())
180    return "nil";
181  else
182    return "0";
183}
184
185namespace {
186
187class ReferenceClear : public RecursiveASTVisitor<ReferenceClear> {
188  ExprSet &Refs;
189public:
190  ReferenceClear(ExprSet &refs) : Refs(refs) { }
191  bool VisitDeclRefExpr(DeclRefExpr *E) { Refs.erase(E); return true; }
192  bool VisitBlockDeclRefExpr(BlockDeclRefExpr *E) { Refs.erase(E); return true; }
193};
194
195class ReferenceCollector : public RecursiveASTVisitor<ReferenceCollector> {
196  ValueDecl *Dcl;
197  ExprSet &Refs;
198
199public:
200  ReferenceCollector(ValueDecl *D, ExprSet &refs)
201    : Dcl(D), Refs(refs) { }
202
203  bool VisitDeclRefExpr(DeclRefExpr *E) {
204    if (E->getDecl() == Dcl)
205      Refs.insert(E);
206    return true;
207  }
208
209  bool VisitBlockDeclRefExpr(BlockDeclRefExpr *E) {
210    if (E->getDecl() == Dcl)
211      Refs.insert(E);
212    return true;
213  }
214};
215
216class RemovablesCollector : public RecursiveASTVisitor<RemovablesCollector> {
217  ExprSet &Removables;
218
219public:
220  RemovablesCollector(ExprSet &removables)
221  : Removables(removables) { }
222
223  bool shouldWalkTypesOfTypeLocs() const { return false; }
224
225  bool TraverseStmtExpr(StmtExpr *E) {
226    CompoundStmt *S = E->getSubStmt();
227    for (CompoundStmt::body_iterator
228        I = S->body_begin(), E = S->body_end(); I != E; ++I) {
229      if (I != E - 1)
230        mark(*I);
231      TraverseStmt(*I);
232    }
233    return true;
234  }
235
236  bool VisitCompoundStmt(CompoundStmt *S) {
237    for (CompoundStmt::body_iterator
238        I = S->body_begin(), E = S->body_end(); I != E; ++I)
239      mark(*I);
240    return true;
241  }
242
243  bool VisitIfStmt(IfStmt *S) {
244    mark(S->getThen());
245    mark(S->getElse());
246    return true;
247  }
248
249  bool VisitWhileStmt(WhileStmt *S) {
250    mark(S->getBody());
251    return true;
252  }
253
254  bool VisitDoStmt(DoStmt *S) {
255    mark(S->getBody());
256    return true;
257  }
258
259  bool VisitForStmt(ForStmt *S) {
260    mark(S->getInit());
261    mark(S->getInc());
262    mark(S->getBody());
263    return true;
264  }
265
266private:
267  void mark(Stmt *S) {
268    if (!S) return;
269
270    while (LabelStmt *Label = dyn_cast<LabelStmt>(S))
271      S = Label->getSubStmt();
272    S = S->IgnoreImplicit();
273    if (Expr *E = dyn_cast<Expr>(S))
274      Removables.insert(E);
275  }
276};
277
278} // end anonymous namespace
279
280void trans::clearRefsIn(Stmt *S, ExprSet &refs) {
281  ReferenceClear(refs).TraverseStmt(S);
282}
283
284void trans::collectRefs(ValueDecl *D, Stmt *S, ExprSet &refs) {
285  ReferenceCollector(D, refs).TraverseStmt(S);
286}
287
288void trans::collectRemovables(Stmt *S, ExprSet &exprs) {
289  RemovablesCollector(exprs).TraverseStmt(S);
290}
291
292//===----------------------------------------------------------------------===//
293// getAllTransformations.
294//===----------------------------------------------------------------------===//
295
296static void independentTransforms(MigrationPass &pass) {
297  rewriteAutoreleasePool(pass);
298  rewriteProperties(pass);
299  removeRetainReleaseDealloc(pass);
300  rewriteUnusedInitDelegate(pass);
301  removeZeroOutPropsInDealloc(pass);
302  makeAssignARCSafe(pass);
303  rewriteUnbridgedCasts(pass);
304  rewriteBlockObjCVariable(pass);
305  checkAPIUses(pass);
306}
307
308std::vector<TransformFn> arcmt::getAllTransformations() {
309  std::vector<TransformFn> transforms;
310
311  transforms.push_back(independentTransforms);
312  // This depends on previous transformations removing various expressions.
313  transforms.push_back(removeEmptyStatementsAndDealloc);
314
315  return transforms;
316}
317