JumpDiagnostics.cpp revision 208600
1193326Sed//===--- JumpDiagnostics.cpp - Analyze Jump Targets for VLA issues --------===// 2193326Sed// 3193326Sed// The LLVM Compiler Infrastructure 4193326Sed// 5193326Sed// This file is distributed under the University of Illinois Open Source 6193326Sed// License. See LICENSE.TXT for details. 7193326Sed// 8193326Sed//===----------------------------------------------------------------------===// 9193326Sed// 10193326Sed// This file implements the JumpScopeChecker class, which is used to diagnose 11193326Sed// jumps that enter a VLA scope in an invalid way. 12193326Sed// 13193326Sed//===----------------------------------------------------------------------===// 14193326Sed 15208600Srdivacky#include "llvm/ADT/BitVector.h" 16193326Sed#include "Sema.h" 17193326Sed#include "clang/AST/Expr.h" 18193326Sed#include "clang/AST/StmtObjC.h" 19193326Sed#include "clang/AST/StmtCXX.h" 20193326Sedusing namespace clang; 21193326Sed 22193326Sednamespace { 23193326Sed 24193326Sed/// JumpScopeChecker - This object is used by Sema to diagnose invalid jumps 25193326Sed/// into VLA and other protected scopes. For example, this rejects: 26193326Sed/// goto L; 27193326Sed/// int a[n]; 28193326Sed/// L: 29193326Sed/// 30193326Sedclass JumpScopeChecker { 31193326Sed Sema &S; 32198092Srdivacky 33193326Sed /// GotoScope - This is a record that we use to keep track of all of the 34193326Sed /// scopes that are introduced by VLAs and other things that scope jumps like 35193326Sed /// gotos. This scope tree has nothing to do with the source scope tree, 36193326Sed /// because you can have multiple VLA scopes per compound statement, and most 37193326Sed /// compound statements don't introduce any scopes. 38193326Sed struct GotoScope { 39193326Sed /// ParentScope - The index in ScopeMap of the parent scope. This is 0 for 40193326Sed /// the parent scope is the function body. 41193326Sed unsigned ParentScope; 42198092Srdivacky 43208600Srdivacky /// InDiag - The diagnostic to emit if there is a jump into this scope. 44208600Srdivacky unsigned InDiag; 45198092Srdivacky 46208600Srdivacky /// OutDiag - The diagnostic to emit if there is an indirect jump out 47208600Srdivacky /// of this scope. Direct jumps always clean up their current scope 48208600Srdivacky /// in an orderly way. 49208600Srdivacky unsigned OutDiag; 50208600Srdivacky 51193326Sed /// Loc - Location to emit the diagnostic. 52193326Sed SourceLocation Loc; 53198092Srdivacky 54208600Srdivacky GotoScope(unsigned parentScope, unsigned InDiag, unsigned OutDiag, 55208600Srdivacky SourceLocation L) 56208600Srdivacky : ParentScope(parentScope), InDiag(InDiag), OutDiag(OutDiag), Loc(L) {} 57193326Sed }; 58198092Srdivacky 59193326Sed llvm::SmallVector<GotoScope, 48> Scopes; 60193326Sed llvm::DenseMap<Stmt*, unsigned> LabelAndGotoScopes; 61193326Sed llvm::SmallVector<Stmt*, 16> Jumps; 62208600Srdivacky 63208600Srdivacky llvm::SmallVector<IndirectGotoStmt*, 4> IndirectJumps; 64208600Srdivacky llvm::SmallVector<LabelStmt*, 4> IndirectJumpTargets; 65193326Sedpublic: 66193326Sed JumpScopeChecker(Stmt *Body, Sema &S); 67193326Sedprivate: 68193326Sed void BuildScopeInformation(Stmt *S, unsigned ParentScope); 69193326Sed void VerifyJumps(); 70208600Srdivacky void VerifyIndirectJumps(); 71208600Srdivacky void DiagnoseIndirectJump(IndirectGotoStmt *IG, unsigned IGScope, 72208600Srdivacky LabelStmt *Target, unsigned TargetScope); 73193326Sed void CheckJump(Stmt *From, Stmt *To, 74193326Sed SourceLocation DiagLoc, unsigned JumpDiag); 75208600Srdivacky 76208600Srdivacky unsigned GetDeepestCommonScope(unsigned A, unsigned B); 77193326Sed}; 78193326Sed} // end anonymous namespace 79193326Sed 80193326Sed 81193326SedJumpScopeChecker::JumpScopeChecker(Stmt *Body, Sema &s) : S(s) { 82193326Sed // Add a scope entry for function scope. 83208600Srdivacky Scopes.push_back(GotoScope(~0U, ~0U, ~0U, SourceLocation())); 84198092Srdivacky 85193326Sed // Build information for the top level compound statement, so that we have a 86193326Sed // defined scope record for every "goto" and label. 87193326Sed BuildScopeInformation(Body, 0); 88198092Srdivacky 89193326Sed // Check that all jumps we saw are kosher. 90193326Sed VerifyJumps(); 91208600Srdivacky VerifyIndirectJumps(); 92193326Sed} 93198092Srdivacky 94208600Srdivacky/// GetDeepestCommonScope - Finds the innermost scope enclosing the 95208600Srdivacky/// two scopes. 96208600Srdivackyunsigned JumpScopeChecker::GetDeepestCommonScope(unsigned A, unsigned B) { 97208600Srdivacky while (A != B) { 98208600Srdivacky // Inner scopes are created after outer scopes and therefore have 99208600Srdivacky // higher indices. 100208600Srdivacky if (A < B) { 101208600Srdivacky assert(Scopes[B].ParentScope < B); 102208600Srdivacky B = Scopes[B].ParentScope; 103208600Srdivacky } else { 104208600Srdivacky assert(Scopes[A].ParentScope < A); 105208600Srdivacky A = Scopes[A].ParentScope; 106208600Srdivacky } 107208600Srdivacky } 108208600Srdivacky return A; 109208600Srdivacky} 110208600Srdivacky 111193326Sed/// GetDiagForGotoScopeDecl - If this decl induces a new goto scope, return a 112193326Sed/// diagnostic that should be emitted if control goes over it. If not, return 0. 113208600Srdivackystatic std::pair<unsigned,unsigned> 114208600Srdivacky GetDiagForGotoScopeDecl(const Decl *D, bool isCPlusPlus) { 115193326Sed if (const VarDecl *VD = dyn_cast<VarDecl>(D)) { 116208600Srdivacky unsigned InDiag = 0, OutDiag = 0; 117193326Sed if (VD->getType()->isVariablyModifiedType()) 118208600Srdivacky InDiag = diag::note_protected_by_vla; 119208600Srdivacky 120208600Srdivacky if (VD->hasAttr<BlocksAttr>()) { 121208600Srdivacky InDiag = diag::note_protected_by___block; 122208600Srdivacky OutDiag = diag::note_exits___block; 123208600Srdivacky } else if (VD->hasAttr<CleanupAttr>()) { 124208600Srdivacky InDiag = diag::note_protected_by_cleanup; 125208600Srdivacky OutDiag = diag::note_exits_cleanup; 126208600Srdivacky } else if (isCPlusPlus) { 127208600Srdivacky // FIXME: In C++0x, we have to check more conditions than "did we 128208600Srdivacky // just give it an initializer?". See 6.7p3. 129208600Srdivacky if (VD->hasLocalStorage() && VD->hasInit()) 130208600Srdivacky InDiag = diag::note_protected_by_variable_init; 131208600Srdivacky 132208600Srdivacky CanQualType T = VD->getType()->getCanonicalTypeUnqualified(); 133208600Srdivacky while (CanQual<ArrayType> AT = T->getAs<ArrayType>()) 134208600Srdivacky T = AT->getElementType(); 135208600Srdivacky if (CanQual<RecordType> RT = T->getAs<RecordType>()) 136208600Srdivacky if (!cast<CXXRecordDecl>(RT->getDecl())->hasTrivialDestructor()) 137208600Srdivacky OutDiag = diag::note_exits_dtor; 138208600Srdivacky } 139204643Srdivacky 140208600Srdivacky return std::make_pair(InDiag, OutDiag); 141208600Srdivacky } 142208600Srdivacky 143208600Srdivacky if (const TypedefDecl *TD = dyn_cast<TypedefDecl>(D)) { 144193326Sed if (TD->getUnderlyingType()->isVariablyModifiedType()) 145208600Srdivacky return std::make_pair((unsigned) diag::note_protected_by_vla_typedef, 0); 146193326Sed } 147198092Srdivacky 148208600Srdivacky return std::make_pair(0U, 0U); 149193326Sed} 150193326Sed 151193326Sed 152193326Sed/// BuildScopeInformation - The statements from CI to CE are known to form a 153193326Sed/// coherent VLA scope with a specified parent node. Walk through the 154193326Sed/// statements, adding any labels or gotos to LabelAndGotoScopes and recursively 155193326Sed/// walking the AST as needed. 156193326Sedvoid JumpScopeChecker::BuildScopeInformation(Stmt *S, unsigned ParentScope) { 157198092Srdivacky 158193326Sed // If we found a label, remember that it is in ParentScope scope. 159208600Srdivacky switch (S->getStmtClass()) { 160208600Srdivacky case Stmt::LabelStmtClass: 161208600Srdivacky case Stmt::DefaultStmtClass: 162208600Srdivacky case Stmt::CaseStmtClass: 163193326Sed LabelAndGotoScopes[S] = ParentScope; 164208600Srdivacky break; 165208600Srdivacky 166208600Srdivacky case Stmt::AddrLabelExprClass: 167208600Srdivacky IndirectJumpTargets.push_back(cast<AddrLabelExpr>(S)->getLabel()); 168208600Srdivacky break; 169208600Srdivacky 170208600Srdivacky case Stmt::IndirectGotoStmtClass: 171208600Srdivacky LabelAndGotoScopes[S] = ParentScope; 172208600Srdivacky IndirectJumps.push_back(cast<IndirectGotoStmt>(S)); 173208600Srdivacky break; 174208600Srdivacky 175208600Srdivacky case Stmt::GotoStmtClass: 176208600Srdivacky case Stmt::SwitchStmtClass: 177193326Sed // Remember both what scope a goto is in as well as the fact that we have 178193326Sed // it. This makes the second scan not have to walk the AST again. 179193326Sed LabelAndGotoScopes[S] = ParentScope; 180193326Sed Jumps.push_back(S); 181208600Srdivacky break; 182208600Srdivacky 183208600Srdivacky default: 184208600Srdivacky break; 185193326Sed } 186198092Srdivacky 187193326Sed for (Stmt::child_iterator CI = S->child_begin(), E = S->child_end(); CI != E; 188193326Sed ++CI) { 189193326Sed Stmt *SubStmt = *CI; 190193326Sed if (SubStmt == 0) continue; 191198092Srdivacky 192204643Srdivacky bool isCPlusPlus = this->S.getLangOptions().CPlusPlus; 193193326Sed 194193326Sed // If this is a declstmt with a VLA definition, it defines a scope from here 195193326Sed // to the end of the containing context. 196193326Sed if (DeclStmt *DS = dyn_cast<DeclStmt>(SubStmt)) { 197204643Srdivacky // The decl statement creates a scope if any of the decls in it are VLAs 198204643Srdivacky // or have the cleanup attribute. 199193326Sed for (DeclStmt::decl_iterator I = DS->decl_begin(), E = DS->decl_end(); 200193326Sed I != E; ++I) { 201193326Sed // If this decl causes a new scope, push and switch to it. 202208600Srdivacky std::pair<unsigned,unsigned> Diags 203208600Srdivacky = GetDiagForGotoScopeDecl(*I, isCPlusPlus); 204208600Srdivacky if (Diags.first || Diags.second) { 205208600Srdivacky Scopes.push_back(GotoScope(ParentScope, Diags.first, Diags.second, 206208600Srdivacky (*I)->getLocation())); 207193326Sed ParentScope = Scopes.size()-1; 208193326Sed } 209198092Srdivacky 210193326Sed // If the decl has an initializer, walk it with the potentially new 211193326Sed // scope we just installed. 212193326Sed if (VarDecl *VD = dyn_cast<VarDecl>(*I)) 213193326Sed if (Expr *Init = VD->getInit()) 214193326Sed BuildScopeInformation(Init, ParentScope); 215193326Sed } 216193326Sed continue; 217193326Sed } 218193326Sed 219193326Sed // Disallow jumps into any part of an @try statement by pushing a scope and 220193326Sed // walking all sub-stmts in that scope. 221193326Sed if (ObjCAtTryStmt *AT = dyn_cast<ObjCAtTryStmt>(SubStmt)) { 222193326Sed // Recursively walk the AST for the @try part. 223208600Srdivacky Scopes.push_back(GotoScope(ParentScope, 224208600Srdivacky diag::note_protected_by_objc_try, 225208600Srdivacky diag::note_exits_objc_try, 226193326Sed AT->getAtTryLoc())); 227193326Sed if (Stmt *TryPart = AT->getTryBody()) 228193326Sed BuildScopeInformation(TryPart, Scopes.size()-1); 229193326Sed 230193326Sed // Jump from the catch to the finally or try is not valid. 231207619Srdivacky for (unsigned I = 0, N = AT->getNumCatchStmts(); I != N; ++I) { 232207619Srdivacky ObjCAtCatchStmt *AC = AT->getCatchStmt(I); 233193326Sed Scopes.push_back(GotoScope(ParentScope, 234193326Sed diag::note_protected_by_objc_catch, 235208600Srdivacky diag::note_exits_objc_catch, 236193326Sed AC->getAtCatchLoc())); 237198092Srdivacky // @catches are nested and it isn't 238193326Sed BuildScopeInformation(AC->getCatchBody(), Scopes.size()-1); 239193326Sed } 240198092Srdivacky 241193326Sed // Jump from the finally to the try or catch is not valid. 242193326Sed if (ObjCAtFinallyStmt *AF = AT->getFinallyStmt()) { 243193326Sed Scopes.push_back(GotoScope(ParentScope, 244193326Sed diag::note_protected_by_objc_finally, 245208600Srdivacky diag::note_exits_objc_finally, 246193326Sed AF->getAtFinallyLoc())); 247193326Sed BuildScopeInformation(AF, Scopes.size()-1); 248193326Sed } 249198092Srdivacky 250193326Sed continue; 251193326Sed } 252198092Srdivacky 253193326Sed // Disallow jumps into the protected statement of an @synchronized, but 254193326Sed // allow jumps into the object expression it protects. 255193326Sed if (ObjCAtSynchronizedStmt *AS = dyn_cast<ObjCAtSynchronizedStmt>(SubStmt)){ 256193326Sed // Recursively walk the AST for the @synchronized object expr, it is 257193326Sed // evaluated in the normal scope. 258193326Sed BuildScopeInformation(AS->getSynchExpr(), ParentScope); 259198092Srdivacky 260193326Sed // Recursively walk the AST for the @synchronized part, protected by a new 261193326Sed // scope. 262193326Sed Scopes.push_back(GotoScope(ParentScope, 263193326Sed diag::note_protected_by_objc_synchronized, 264208600Srdivacky diag::note_exits_objc_synchronized, 265193326Sed AS->getAtSynchronizedLoc())); 266193326Sed BuildScopeInformation(AS->getSynchBody(), Scopes.size()-1); 267193326Sed continue; 268193326Sed } 269193326Sed 270193326Sed // Disallow jumps into any part of a C++ try statement. This is pretty 271193326Sed // much the same as for Obj-C. 272193326Sed if (CXXTryStmt *TS = dyn_cast<CXXTryStmt>(SubStmt)) { 273208600Srdivacky Scopes.push_back(GotoScope(ParentScope, 274208600Srdivacky diag::note_protected_by_cxx_try, 275208600Srdivacky diag::note_exits_cxx_try, 276193326Sed TS->getSourceRange().getBegin())); 277193326Sed if (Stmt *TryBlock = TS->getTryBlock()) 278193326Sed BuildScopeInformation(TryBlock, Scopes.size()-1); 279193326Sed 280193326Sed // Jump from the catch into the try is not allowed either. 281198092Srdivacky for (unsigned I = 0, E = TS->getNumHandlers(); I != E; ++I) { 282193326Sed CXXCatchStmt *CS = TS->getHandler(I); 283193326Sed Scopes.push_back(GotoScope(ParentScope, 284193326Sed diag::note_protected_by_cxx_catch, 285208600Srdivacky diag::note_exits_cxx_catch, 286193326Sed CS->getSourceRange().getBegin())); 287193326Sed BuildScopeInformation(CS->getHandlerBlock(), Scopes.size()-1); 288193326Sed } 289193326Sed 290193326Sed continue; 291193326Sed } 292193326Sed 293193326Sed // Recursively walk the AST. 294193326Sed BuildScopeInformation(SubStmt, ParentScope); 295193326Sed } 296193326Sed} 297193326Sed 298193326Sed/// VerifyJumps - Verify each element of the Jumps array to see if they are 299193326Sed/// valid, emitting diagnostics if not. 300193326Sedvoid JumpScopeChecker::VerifyJumps() { 301193326Sed while (!Jumps.empty()) { 302193326Sed Stmt *Jump = Jumps.pop_back_val(); 303198092Srdivacky 304198092Srdivacky // With a goto, 305193326Sed if (GotoStmt *GS = dyn_cast<GotoStmt>(Jump)) { 306193326Sed CheckJump(GS, GS->getLabel(), GS->getGotoLoc(), 307193326Sed diag::err_goto_into_protected_scope); 308193326Sed continue; 309193326Sed } 310198092Srdivacky 311208600Srdivacky SwitchStmt *SS = cast<SwitchStmt>(Jump); 312208600Srdivacky for (SwitchCase *SC = SS->getSwitchCaseList(); SC; 313208600Srdivacky SC = SC->getNextSwitchCase()) { 314208600Srdivacky assert(LabelAndGotoScopes.count(SC) && "Case not visited?"); 315208600Srdivacky CheckJump(SS, SC, SC->getLocStart(), 316208600Srdivacky diag::err_switch_into_protected_scope); 317193326Sed } 318208600Srdivacky } 319208600Srdivacky} 320193326Sed 321208600Srdivacky/// VerifyIndirectJumps - Verify whether any possible indirect jump 322208600Srdivacky/// might cross a protection boundary. Unlike direct jumps, indirect 323208600Srdivacky/// jumps count cleanups as protection boundaries: since there's no 324208600Srdivacky/// way to know where the jump is going, we can't implicitly run the 325208600Srdivacky/// right cleanups the way we can with direct jumps. 326208600Srdivacky/// 327208600Srdivacky/// Thus, an indirect jump is "trivial" if it bypasses no 328208600Srdivacky/// initializations and no teardowns. More formally, an indirect jump 329208600Srdivacky/// from A to B is trivial if the path out from A to DCA(A,B) is 330208600Srdivacky/// trivial and the path in from DCA(A,B) to B is trivial, where 331208600Srdivacky/// DCA(A,B) is the deepest common ancestor of A and B. 332208600Srdivacky/// Jump-triviality is transitive but asymmetric. 333208600Srdivacky/// 334208600Srdivacky/// A path in is trivial if none of the entered scopes have an InDiag. 335208600Srdivacky/// A path out is trivial is none of the exited scopes have an OutDiag. 336208600Srdivacky/// 337208600Srdivacky/// Under these definitions, this function checks that the indirect 338208600Srdivacky/// jump between A and B is trivial for every indirect goto statement A 339208600Srdivacky/// and every label B whose address was taken in the function. 340208600Srdivackyvoid JumpScopeChecker::VerifyIndirectJumps() { 341208600Srdivacky if (IndirectJumps.empty()) return; 342198092Srdivacky 343208600Srdivacky // If there aren't any address-of-label expressions in this function, 344208600Srdivacky // complain about the first indirect goto. 345208600Srdivacky if (IndirectJumpTargets.empty()) { 346208600Srdivacky S.Diag(IndirectJumps[0]->getGotoLoc(), 347208600Srdivacky diag::err_indirect_goto_without_addrlabel); 348208600Srdivacky return; 349208600Srdivacky } 350198092Srdivacky 351208600Srdivacky // Collect a single representative of every scope containing an 352208600Srdivacky // indirect goto. For most code bases, this substantially cuts 353208600Srdivacky // down on the number of jump sites we'll have to consider later. 354208600Srdivacky typedef std::pair<unsigned, IndirectGotoStmt*> JumpScope; 355208600Srdivacky llvm::SmallVector<JumpScope, 32> JumpScopes; 356208600Srdivacky { 357208600Srdivacky llvm::DenseMap<unsigned, IndirectGotoStmt*> JumpScopesMap; 358208600Srdivacky for (llvm::SmallVectorImpl<IndirectGotoStmt*>::iterator 359208600Srdivacky I = IndirectJumps.begin(), E = IndirectJumps.end(); I != E; ++I) { 360208600Srdivacky IndirectGotoStmt *IG = *I; 361208600Srdivacky assert(LabelAndGotoScopes.count(IG) && 362208600Srdivacky "indirect jump didn't get added to scopes?"); 363208600Srdivacky unsigned IGScope = LabelAndGotoScopes[IG]; 364208600Srdivacky IndirectGotoStmt *&Entry = JumpScopesMap[IGScope]; 365208600Srdivacky if (!Entry) Entry = IG; 366208600Srdivacky } 367208600Srdivacky JumpScopes.reserve(JumpScopesMap.size()); 368208600Srdivacky for (llvm::DenseMap<unsigned, IndirectGotoStmt*>::iterator 369208600Srdivacky I = JumpScopesMap.begin(), E = JumpScopesMap.end(); I != E; ++I) 370208600Srdivacky JumpScopes.push_back(*I); 371208600Srdivacky } 372198092Srdivacky 373208600Srdivacky // Collect a single representative of every scope containing a 374208600Srdivacky // label whose address was taken somewhere in the function. 375208600Srdivacky // For most code bases, there will be only one such scope. 376208600Srdivacky llvm::DenseMap<unsigned, LabelStmt*> TargetScopes; 377208600Srdivacky for (llvm::SmallVectorImpl<LabelStmt*>::iterator 378208600Srdivacky I = IndirectJumpTargets.begin(), E = IndirectJumpTargets.end(); 379208600Srdivacky I != E; ++I) { 380208600Srdivacky LabelStmt *TheLabel = *I; 381208600Srdivacky assert(LabelAndGotoScopes.count(TheLabel) && 382208600Srdivacky "Referenced label didn't get added to scopes?"); 383208600Srdivacky unsigned LabelScope = LabelAndGotoScopes[TheLabel]; 384208600Srdivacky LabelStmt *&Target = TargetScopes[LabelScope]; 385208600Srdivacky if (!Target) Target = TheLabel; 386208600Srdivacky } 387208600Srdivacky 388208600Srdivacky // For each target scope, make sure it's trivially reachable from 389208600Srdivacky // every scope containing a jump site. 390208600Srdivacky // 391208600Srdivacky // A path between scopes always consists of exitting zero or more 392208600Srdivacky // scopes, then entering zero or more scopes. We build a set of 393208600Srdivacky // of scopes S from which the target scope can be trivially 394208600Srdivacky // entered, then verify that every jump scope can be trivially 395208600Srdivacky // exitted to reach a scope in S. 396208600Srdivacky llvm::BitVector Reachable(Scopes.size(), false); 397208600Srdivacky for (llvm::DenseMap<unsigned,LabelStmt*>::iterator 398208600Srdivacky TI = TargetScopes.begin(), TE = TargetScopes.end(); TI != TE; ++TI) { 399208600Srdivacky unsigned TargetScope = TI->first; 400208600Srdivacky LabelStmt *TargetLabel = TI->second; 401208600Srdivacky 402208600Srdivacky Reachable.reset(); 403208600Srdivacky 404208600Srdivacky // Mark all the enclosing scopes from which you can safely jump 405208600Srdivacky // into the target scope. 'Min' will end up being the index of 406208600Srdivacky // the shallowest such scope. 407208600Srdivacky unsigned Min = TargetScope; 408208600Srdivacky while (true) { 409208600Srdivacky Reachable.set(Min); 410208600Srdivacky 411208600Srdivacky // Don't go beyond the outermost scope. 412208600Srdivacky if (Min == 0) break; 413208600Srdivacky 414208600Srdivacky // Stop if we can't trivially enter the current scope. 415208600Srdivacky if (Scopes[Min].InDiag) break; 416208600Srdivacky 417208600Srdivacky Min = Scopes[Min].ParentScope; 418193326Sed } 419193326Sed 420208600Srdivacky // Walk through all the jump sites, checking that they can trivially 421208600Srdivacky // reach this label scope. 422208600Srdivacky for (llvm::SmallVectorImpl<JumpScope>::iterator 423208600Srdivacky I = JumpScopes.begin(), E = JumpScopes.end(); I != E; ++I) { 424208600Srdivacky unsigned Scope = I->first; 425208600Srdivacky 426208600Srdivacky // Walk out the "scope chain" for this scope, looking for a scope 427208600Srdivacky // we've marked reachable. For well-formed code this amortizes 428208600Srdivacky // to O(JumpScopes.size() / Scopes.size()): we only iterate 429208600Srdivacky // when we see something unmarked, and in well-formed code we 430208600Srdivacky // mark everything we iterate past. 431208600Srdivacky bool IsReachable = false; 432208600Srdivacky while (true) { 433208600Srdivacky if (Reachable.test(Scope)) { 434208600Srdivacky // If we find something reachable, mark all the scopes we just 435208600Srdivacky // walked through as reachable. 436208600Srdivacky for (unsigned S = I->first; S != Scope; S = Scopes[S].ParentScope) 437208600Srdivacky Reachable.set(S); 438208600Srdivacky IsReachable = true; 439208600Srdivacky break; 440208600Srdivacky } 441208600Srdivacky 442208600Srdivacky // Don't walk out if we've reached the top-level scope or we've 443208600Srdivacky // gotten shallower than the shallowest reachable scope. 444208600Srdivacky if (Scope == 0 || Scope < Min) break; 445208600Srdivacky 446208600Srdivacky // Don't walk out through an out-diagnostic. 447208600Srdivacky if (Scopes[Scope].OutDiag) break; 448208600Srdivacky 449208600Srdivacky Scope = Scopes[Scope].ParentScope; 450208600Srdivacky } 451208600Srdivacky 452208600Srdivacky // Only diagnose if we didn't find something. 453208600Srdivacky if (IsReachable) continue; 454208600Srdivacky 455208600Srdivacky DiagnoseIndirectJump(I->second, I->first, TargetLabel, TargetScope); 456193326Sed } 457193326Sed } 458193326Sed} 459193326Sed 460208600Srdivacky/// Diagnose an indirect jump which is known to cross scopes. 461208600Srdivackyvoid JumpScopeChecker::DiagnoseIndirectJump(IndirectGotoStmt *Jump, 462208600Srdivacky unsigned JumpScope, 463208600Srdivacky LabelStmt *Target, 464208600Srdivacky unsigned TargetScope) { 465208600Srdivacky assert(JumpScope != TargetScope); 466208600Srdivacky 467208600Srdivacky S.Diag(Jump->getGotoLoc(), diag::warn_indirect_goto_in_protected_scope); 468208600Srdivacky S.Diag(Target->getIdentLoc(), diag::note_indirect_goto_target); 469208600Srdivacky 470208600Srdivacky unsigned Common = GetDeepestCommonScope(JumpScope, TargetScope); 471208600Srdivacky 472208600Srdivacky // Walk out the scope chain until we reach the common ancestor. 473208600Srdivacky for (unsigned I = JumpScope; I != Common; I = Scopes[I].ParentScope) 474208600Srdivacky if (Scopes[I].OutDiag) 475208600Srdivacky S.Diag(Scopes[I].Loc, Scopes[I].OutDiag); 476208600Srdivacky 477208600Srdivacky // Now walk into the scopes containing the label whose address was taken. 478208600Srdivacky for (unsigned I = TargetScope; I != Common; I = Scopes[I].ParentScope) 479208600Srdivacky if (Scopes[I].InDiag) 480208600Srdivacky S.Diag(Scopes[I].Loc, Scopes[I].InDiag); 481208600Srdivacky} 482208600Srdivacky 483193326Sed/// CheckJump - Validate that the specified jump statement is valid: that it is 484193326Sed/// jumping within or out of its current scope, not into a deeper one. 485193326Sedvoid JumpScopeChecker::CheckJump(Stmt *From, Stmt *To, 486193326Sed SourceLocation DiagLoc, unsigned JumpDiag) { 487193326Sed assert(LabelAndGotoScopes.count(From) && "Jump didn't get added to scopes?"); 488193326Sed unsigned FromScope = LabelAndGotoScopes[From]; 489193326Sed 490193326Sed assert(LabelAndGotoScopes.count(To) && "Jump didn't get added to scopes?"); 491193326Sed unsigned ToScope = LabelAndGotoScopes[To]; 492198092Srdivacky 493193326Sed // Common case: exactly the same scope, which is fine. 494193326Sed if (FromScope == ToScope) return; 495198092Srdivacky 496208600Srdivacky unsigned CommonScope = GetDeepestCommonScope(FromScope, ToScope); 497198092Srdivacky 498208600Srdivacky // It's okay to jump out from a nested scope. 499208600Srdivacky if (CommonScope == ToScope) return; 500198092Srdivacky 501208600Srdivacky // Pull out (and reverse) any scopes we might need to diagnose skipping. 502208600Srdivacky llvm::SmallVector<unsigned, 10> ToScopes; 503208600Srdivacky for (unsigned I = ToScope; I != CommonScope; I = Scopes[I].ParentScope) 504208600Srdivacky if (Scopes[I].InDiag) 505208600Srdivacky ToScopes.push_back(I); 506193326Sed 507208600Srdivacky // If the only scopes present are cleanup scopes, we're okay. 508208600Srdivacky if (ToScopes.empty()) return; 509193326Sed 510208600Srdivacky S.Diag(DiagLoc, JumpDiag); 511198092Srdivacky 512193326Sed // Emit diagnostics for whatever is left in ToScopes. 513193326Sed for (unsigned i = 0, e = ToScopes.size(); i != e; ++i) 514208600Srdivacky S.Diag(Scopes[ToScopes[i]].Loc, Scopes[ToScopes[i]].InDiag); 515193326Sed} 516193326Sed 517193326Sedvoid Sema::DiagnoseInvalidJumps(Stmt *Body) { 518199482Srdivacky (void)JumpScopeChecker(Body, *this); 519193326Sed} 520