1 //===--- TransEmptyStatements.cpp - Transformations 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 // removeEmptyStatementsAndDealloc: 11 // 12 // Removes empty statements that are leftovers from previous transformations. 13 // e.g for 14 // 15 // [x retain]; 16 // 17 // removeRetainReleaseDealloc will leave an empty ";" that removeEmptyStatements 18 // will remove. 19 // 20 //===----------------------------------------------------------------------===// 21 22 #include "Transforms.h" 23 #include "Internals.h" 24 #include "clang/AST/ASTContext.h" 25 #include "clang/AST/StmtVisitor.h" 26 #include "clang/Basic/SourceManager.h" 27 28 using namespace clang; 29 using namespace arcmt; 30 using namespace trans; 31 32 static bool isEmptyARCMTMacroStatement(NullStmt *S, 33 std::vector<SourceLocation> &MacroLocs, 34 ASTContext &Ctx) { 35 if (!S->hasLeadingEmptyMacro()) 36 return false; 37 38 SourceLocation SemiLoc = S->getSemiLoc(); 39 if (SemiLoc.isInvalid() || SemiLoc.isMacroID()) 40 return false; 41 42 if (MacroLocs.empty()) 43 return false; 44 45 SourceManager &SM = Ctx.getSourceManager(); 46 std::vector<SourceLocation>::iterator 47 I = std::upper_bound(MacroLocs.begin(), MacroLocs.end(), SemiLoc, 48 BeforeThanCompare<SourceLocation>(SM)); 49 --I; 50 SourceLocation 51 AfterMacroLoc = I->getLocWithOffset(getARCMTMacroName().size()); 52 assert(AfterMacroLoc.isFileID()); 53 54 if (AfterMacroLoc == SemiLoc) 55 return true; 56 57 int RelOffs = 0; 58 if (!SM.isInSameSLocAddrSpace(AfterMacroLoc, SemiLoc, &RelOffs)) 59 return false; 60 if (RelOffs < 0) 61 return false; 62 63 // We make the reasonable assumption that a semicolon after 100 characters 64 // means that it is not the next token after our macro. If this assumption 65 // fails it is not critical, we will just fail to clear out, e.g., an empty 66 // 'if'. 67 if (RelOffs - getARCMTMacroName().size() > 100) 68 return false; 69 70 SourceLocation AfterMacroSemiLoc = findSemiAfterLocation(AfterMacroLoc, Ctx); 71 return AfterMacroSemiLoc == SemiLoc; 72 } 73 74 namespace { 75 76 /// \brief Returns true if the statement became empty due to previous 77 /// transformations. 78 class EmptyChecker : public StmtVisitor<EmptyChecker, bool> { 79 ASTContext &Ctx; 80 std::vector<SourceLocation> &MacroLocs; 81 82 public: 83 EmptyChecker(ASTContext &ctx, std::vector<SourceLocation> ¯oLocs) 84 : Ctx(ctx), MacroLocs(macroLocs) { } 85 86 bool VisitNullStmt(NullStmt *S) { 87 return isEmptyARCMTMacroStatement(S, MacroLocs, Ctx); 88 } 89 bool VisitCompoundStmt(CompoundStmt *S) { 90 if (S->body_empty()) 91 return false; // was already empty, not because of transformations. 92 for (auto *I : S->body()) 93 if (!Visit(I)) 94 return false; 95 return true; 96 } 97 bool VisitIfStmt(IfStmt *S) { 98 if (S->getConditionVariable()) 99 return false; 100 Expr *condE = S->getCond(); 101 if (!condE) 102 return false; 103 if (hasSideEffects(condE, Ctx)) 104 return false; 105 if (!S->getThen() || !Visit(S->getThen())) 106 return false; 107 if (S->getElse() && !Visit(S->getElse())) 108 return false; 109 return true; 110 } 111 bool VisitWhileStmt(WhileStmt *S) { 112 if (S->getConditionVariable()) 113 return false; 114 Expr *condE = S->getCond(); 115 if (!condE) 116 return false; 117 if (hasSideEffects(condE, Ctx)) 118 return false; 119 if (!S->getBody()) 120 return false; 121 return Visit(S->getBody()); 122 } 123 bool VisitDoStmt(DoStmt *S) { 124 Expr *condE = S->getCond(); 125 if (!condE) 126 return false; 127 if (hasSideEffects(condE, Ctx)) 128 return false; 129 if (!S->getBody()) 130 return false; 131 return Visit(S->getBody()); 132 } 133 bool VisitObjCForCollectionStmt(ObjCForCollectionStmt *S) { 134 Expr *Exp = S->getCollection(); 135 if (!Exp) 136 return false; 137 if (hasSideEffects(Exp, Ctx)) 138 return false; 139 if (!S->getBody()) 140 return false; 141 return Visit(S->getBody()); 142 } 143 bool VisitObjCAutoreleasePoolStmt(ObjCAutoreleasePoolStmt *S) { 144 if (!S->getSubStmt()) 145 return false; 146 return Visit(S->getSubStmt()); 147 } 148 }; 149 150 class EmptyStatementsRemover : 151 public RecursiveASTVisitor<EmptyStatementsRemover> { 152 MigrationPass &Pass; 153 154 public: 155 EmptyStatementsRemover(MigrationPass &pass) : Pass(pass) { } 156 157 bool TraverseStmtExpr(StmtExpr *E) { 158 CompoundStmt *S = E->getSubStmt(); 159 for (CompoundStmt::body_iterator 160 I = S->body_begin(), E = S->body_end(); I != E; ++I) { 161 if (I != E - 1) 162 check(*I); 163 TraverseStmt(*I); 164 } 165 return true; 166 } 167 168 bool VisitCompoundStmt(CompoundStmt *S) { 169 for (auto *I : S->body()) 170 check(I); 171 return true; 172 } 173 174 ASTContext &getContext() { return Pass.Ctx; } 175 176 private: 177 void check(Stmt *S) { 178 if (!S) return; 179 if (EmptyChecker(Pass.Ctx, Pass.ARCMTMacroLocs).Visit(S)) { 180 Transaction Trans(Pass.TA); 181 Pass.TA.removeStmt(S); 182 } 183 } 184 }; 185 186 } // anonymous namespace 187 188 static bool isBodyEmpty(CompoundStmt *body, ASTContext &Ctx, 189 std::vector<SourceLocation> &MacroLocs) { 190 for (auto *I : body->body()) 191 if (!EmptyChecker(Ctx, MacroLocs).Visit(I)) 192 return false; 193 194 return true; 195 } 196 197 static void cleanupDeallocOrFinalize(MigrationPass &pass) { 198 ASTContext &Ctx = pass.Ctx; 199 TransformActions &TA = pass.TA; 200 DeclContext *DC = Ctx.getTranslationUnitDecl(); 201 Selector FinalizeSel = 202 Ctx.Selectors.getNullarySelector(&pass.Ctx.Idents.get("finalize")); 203 204 typedef DeclContext::specific_decl_iterator<ObjCImplementationDecl> 205 impl_iterator; 206 for (impl_iterator I = impl_iterator(DC->decls_begin()), 207 E = impl_iterator(DC->decls_end()); I != E; ++I) { 208 ObjCMethodDecl *DeallocM = nullptr; 209 ObjCMethodDecl *FinalizeM = nullptr; 210 for (auto *MD : I->instance_methods()) { 211 if (!MD->hasBody()) 212 continue; 213 214 if (MD->getMethodFamily() == OMF_dealloc) { 215 DeallocM = MD; 216 } else if (MD->isInstanceMethod() && MD->getSelector() == FinalizeSel) { 217 FinalizeM = MD; 218 } 219 } 220 221 if (DeallocM) { 222 if (isBodyEmpty(DeallocM->getCompoundBody(), Ctx, pass.ARCMTMacroLocs)) { 223 Transaction Trans(TA); 224 TA.remove(DeallocM->getSourceRange()); 225 } 226 227 if (FinalizeM) { 228 Transaction Trans(TA); 229 TA.remove(FinalizeM->getSourceRange()); 230 } 231 232 } else if (FinalizeM) { 233 if (isBodyEmpty(FinalizeM->getCompoundBody(), Ctx, pass.ARCMTMacroLocs)) { 234 Transaction Trans(TA); 235 TA.remove(FinalizeM->getSourceRange()); 236 } else { 237 Transaction Trans(TA); 238 TA.replaceText(FinalizeM->getSelectorStartLoc(), "finalize", "dealloc"); 239 } 240 } 241 } 242 } 243 244 void trans::removeEmptyStatementsAndDeallocFinalize(MigrationPass &pass) { 245 EmptyStatementsRemover(pass).TraverseDecl(pass.Ctx.getTranslationUnitDecl()); 246 247 cleanupDeallocOrFinalize(pass); 248 249 for (unsigned i = 0, e = pass.ARCMTMacroLocs.size(); i != e; ++i) { 250 Transaction Trans(pass.TA); 251 pass.TA.remove(pass.ARCMTMacroLocs[i]); 252 } 253 } 254
