BodyFarm.cpp revision 55fc873017f10f6f566b182b70f6fc22aefa3464
1//== BodyFarm.cpp - Factory for conjuring up fake bodies ----------*- C++ -*-// 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// BodyFarm is a factory for creating faux implementations for functions/methods 11// for analysis purposes. 12// 13//===----------------------------------------------------------------------===// 14 15#include "BodyFarm.h" 16#include "clang/AST/ASTContext.h" 17#include "clang/AST/Decl.h" 18#include "clang/AST/Expr.h" 19#include "clang/AST/ExprObjC.h" 20#include "llvm/ADT/StringSwitch.h" 21 22using namespace clang; 23 24//===----------------------------------------------------------------------===// 25// Helper creation functions for constructing faux ASTs. 26//===----------------------------------------------------------------------===// 27 28static bool isDispatchBlock(QualType Ty) { 29 // Is it a block pointer? 30 const BlockPointerType *BPT = Ty->getAs<BlockPointerType>(); 31 if (!BPT) 32 return false; 33 34 // Check if the block pointer type takes no arguments and 35 // returns void. 36 const FunctionProtoType *FT = 37 BPT->getPointeeType()->getAs<FunctionProtoType>(); 38 if (!FT || !FT->getResultType()->isVoidType() || 39 FT->getNumArgs() != 0) 40 return false; 41 42 return true; 43} 44 45namespace { 46class ASTMaker { 47public: 48 ASTMaker(ASTContext &C) : C(C) {} 49 50 /// Create a new BinaryOperator representing a simple assignment. 51 BinaryOperator *makeAssignment(const Expr *LHS, const Expr *RHS, QualType Ty); 52 53 /// Create a new BinaryOperator representing a comparison. 54 BinaryOperator *makeComparison(const Expr *LHS, const Expr *RHS, 55 BinaryOperator::Opcode Op); 56 57 /// Create a new compound stmt using the provided statements. 58 CompoundStmt *makeCompound(ArrayRef<Stmt*>); 59 60 /// Create a new DeclRefExpr for the referenced variable. 61 DeclRefExpr *makeDeclRefExpr(const VarDecl *D); 62 63 /// Create a new UnaryOperator representing a dereference. 64 UnaryOperator *makeDereference(const Expr *Arg, QualType Ty); 65 66 /// Create an implicit cast for an integer conversion. 67 Expr *makeIntegralCast(const Expr *Arg, QualType Ty); 68 69 /// Create an implicit cast to a builtin boolean type. 70 ImplicitCastExpr *makeIntegralCastToBoolean(const Expr *Arg); 71 72 // Create an implicit cast for lvalue-to-rvaluate conversions. 73 ImplicitCastExpr *makeLvalueToRvalue(const Expr *Arg, QualType Ty); 74 75 /// Create an Objective-C bool literal. 76 ObjCBoolLiteralExpr *makeObjCBool(bool Val); 77 78 /// Create a Return statement. 79 ReturnStmt *makeReturn(const Expr *RetVal); 80 81private: 82 ASTContext &C; 83}; 84} 85 86BinaryOperator *ASTMaker::makeAssignment(const Expr *LHS, const Expr *RHS, 87 QualType Ty) { 88 return new (C) BinaryOperator(const_cast<Expr*>(LHS), const_cast<Expr*>(RHS), 89 BO_Assign, Ty, VK_RValue, 90 OK_Ordinary, SourceLocation(), false); 91} 92 93BinaryOperator *ASTMaker::makeComparison(const Expr *LHS, const Expr *RHS, 94 BinaryOperator::Opcode Op) { 95 assert(BinaryOperator::isLogicalOp(Op) || 96 BinaryOperator::isComparisonOp(Op)); 97 return new (C) BinaryOperator(const_cast<Expr*>(LHS), 98 const_cast<Expr*>(RHS), 99 Op, 100 C.getLogicalOperationType(), 101 VK_RValue, 102 OK_Ordinary, SourceLocation(), false); 103} 104 105CompoundStmt *ASTMaker::makeCompound(ArrayRef<Stmt *> Stmts) { 106 return new (C) CompoundStmt(C, const_cast<Stmt**>(Stmts.data()), 107 Stmts.size(), 108 SourceLocation(), SourceLocation()); 109} 110 111DeclRefExpr *ASTMaker::makeDeclRefExpr(const VarDecl *D) { 112 DeclRefExpr *DR = 113 DeclRefExpr::Create(/* Ctx = */ C, 114 /* QualifierLoc = */ NestedNameSpecifierLoc(), 115 /* TemplateKWLoc = */ SourceLocation(), 116 /* D = */ const_cast<VarDecl*>(D), 117 /* isEnclosingLocal = */ false, 118 /* NameLoc = */ SourceLocation(), 119 /* T = */ D->getType(), 120 /* VK = */ VK_LValue); 121 return DR; 122} 123 124UnaryOperator *ASTMaker::makeDereference(const Expr *Arg, QualType Ty) { 125 return new (C) UnaryOperator(const_cast<Expr*>(Arg), UO_Deref, Ty, 126 VK_LValue, OK_Ordinary, SourceLocation()); 127} 128 129ImplicitCastExpr *ASTMaker::makeLvalueToRvalue(const Expr *Arg, QualType Ty) { 130 return ImplicitCastExpr::Create(C, Ty, CK_LValueToRValue, 131 const_cast<Expr*>(Arg), 0, VK_RValue); 132} 133 134Expr *ASTMaker::makeIntegralCast(const Expr *Arg, QualType Ty) { 135 if (Arg->getType() == Ty) 136 return const_cast<Expr*>(Arg); 137 138 return ImplicitCastExpr::Create(C, Ty, CK_IntegralCast, 139 const_cast<Expr*>(Arg), 0, VK_RValue); 140} 141 142ImplicitCastExpr *ASTMaker::makeIntegralCastToBoolean(const Expr *Arg) { 143 return ImplicitCastExpr::Create(C, C.BoolTy, CK_IntegralToBoolean, 144 const_cast<Expr*>(Arg), 0, VK_RValue); 145} 146 147ObjCBoolLiteralExpr *ASTMaker::makeObjCBool(bool Val) { 148 QualType Ty = C.getBOOLDecl() ? C.getBOOLType() : C.ObjCBuiltinBoolTy; 149 return new (C) ObjCBoolLiteralExpr(Val, Ty, SourceLocation()); 150} 151 152ReturnStmt *ASTMaker::makeReturn(const Expr *RetVal) { 153 return new (C) ReturnStmt(SourceLocation(), const_cast<Expr*>(RetVal), 0); 154} 155 156//===----------------------------------------------------------------------===// 157// Creation functions for faux ASTs. 158//===----------------------------------------------------------------------===// 159 160typedef Stmt *(*FunctionFarmer)(ASTContext &C, const FunctionDecl *D); 161 162/// Create a fake body for dispatch_once. 163static Stmt *create_dispatch_once(ASTContext &C, const FunctionDecl *D) { 164 // Check if we have at least two parameters. 165 if (D->param_size() != 2) 166 return 0; 167 168 // Check if the first parameter is a pointer to integer type. 169 const ParmVarDecl *Predicate = D->getParamDecl(0); 170 QualType PredicateQPtrTy = Predicate->getType(); 171 const PointerType *PredicatePtrTy = PredicateQPtrTy->getAs<PointerType>(); 172 if (!PredicatePtrTy) 173 return 0; 174 QualType PredicateTy = PredicatePtrTy->getPointeeType(); 175 if (!PredicateTy->isIntegerType()) 176 return 0; 177 178 // Check if the second parameter is the proper block type. 179 const ParmVarDecl *Block = D->getParamDecl(1); 180 QualType Ty = Block->getType(); 181 if (!isDispatchBlock(Ty)) 182 return 0; 183 184 // Everything checks out. Create a fakse body that checks the predicate, 185 // sets it, and calls the block. Basically, an AST dump of: 186 // 187 // void dispatch_once(dispatch_once_t *predicate, dispatch_block_t block) { 188 // if (!*predicate) { 189 // *predicate = 1; 190 // block(); 191 // } 192 // } 193 194 ASTMaker M(C); 195 196 // (1) Create the call. 197 DeclRefExpr *DR = M.makeDeclRefExpr(Block); 198 ImplicitCastExpr *ICE = M.makeLvalueToRvalue(DR, Ty); 199 CallExpr *CE = new (C) CallExpr(C, ICE, ArrayRef<Expr*>(), C.VoidTy, 200 VK_RValue, SourceLocation()); 201 202 // (2) Create the assignment to the predicate. 203 IntegerLiteral *IL = 204 IntegerLiteral::Create(C, llvm::APInt(C.getTypeSize(C.IntTy), (uint64_t) 1), 205 C.IntTy, SourceLocation()); 206 BinaryOperator *B = 207 M.makeAssignment( 208 M.makeDereference( 209 M.makeLvalueToRvalue( 210 M.makeDeclRefExpr(Predicate), PredicateQPtrTy), 211 PredicateTy), 212 M.makeIntegralCast(IL, PredicateTy), 213 PredicateTy); 214 215 // (3) Create the compound statement. 216 Stmt *Stmts[2]; 217 Stmts[0] = B; 218 Stmts[1] = CE; 219 CompoundStmt *CS = M.makeCompound(ArrayRef<Stmt*>(Stmts, 2)); 220 221 // (4) Create the 'if' condition. 222 ImplicitCastExpr *LValToRval = 223 M.makeLvalueToRvalue( 224 M.makeDereference( 225 M.makeLvalueToRvalue( 226 M.makeDeclRefExpr(Predicate), 227 PredicateQPtrTy), 228 PredicateTy), 229 PredicateTy); 230 231 UnaryOperator *UO = new (C) UnaryOperator(LValToRval, UO_LNot, C.IntTy, 232 VK_RValue, OK_Ordinary, 233 SourceLocation()); 234 235 // (5) Create the 'if' statement. 236 IfStmt *If = new (C) IfStmt(C, SourceLocation(), 0, UO, CS); 237 return If; 238} 239 240/// Create a fake body for dispatch_sync. 241static Stmt *create_dispatch_sync(ASTContext &C, const FunctionDecl *D) { 242 // Check if we have at least two parameters. 243 if (D->param_size() != 2) 244 return 0; 245 246 // Check if the second parameter is a block. 247 const ParmVarDecl *PV = D->getParamDecl(1); 248 QualType Ty = PV->getType(); 249 if (!isDispatchBlock(Ty)) 250 return 0; 251 252 // Everything checks out. Create a fake body that just calls the block. 253 // This is basically just an AST dump of: 254 // 255 // void dispatch_sync(dispatch_queue_t queue, void (^block)(void)) { 256 // block(); 257 // } 258 // 259 ASTMaker M(C); 260 DeclRefExpr *DR = M.makeDeclRefExpr(PV); 261 ImplicitCastExpr *ICE = M.makeLvalueToRvalue(DR, Ty); 262 CallExpr *CE = new (C) CallExpr(C, ICE, ArrayRef<Expr*>(), C.VoidTy, 263 VK_RValue, SourceLocation()); 264 return CE; 265} 266 267static Stmt *create_OSAtomicCompareAndSwap(ASTContext &C, const FunctionDecl *D) 268{ 269 // There are exactly 3 arguments. 270 if (D->param_size() != 3) 271 return 0; 272 273 // Body for: 274 // if (oldValue == *theValue) { 275 // *theValue = newValue; 276 // return YES; 277 // } 278 // else return NO; 279 280 QualType ResultTy = D->getResultType(); 281 bool isBoolean = ResultTy->isBooleanType(); 282 if (!isBoolean && !ResultTy->isIntegralType(C)) 283 return 0; 284 285 const ParmVarDecl *OldValue = D->getParamDecl(0); 286 QualType OldValueTy = OldValue->getType(); 287 288 const ParmVarDecl *NewValue = D->getParamDecl(1); 289 QualType NewValueTy = NewValue->getType(); 290 291 assert(OldValueTy == NewValueTy); 292 293 const ParmVarDecl *TheValue = D->getParamDecl(2); 294 QualType TheValueTy = TheValue->getType(); 295 const PointerType *PT = TheValueTy->getAs<PointerType>(); 296 if (!PT) 297 return 0; 298 QualType PointeeTy = PT->getPointeeType(); 299 300 ASTMaker M(C); 301 // Construct the comparison. 302 Expr *Comparison = 303 M.makeComparison( 304 M.makeLvalueToRvalue(M.makeDeclRefExpr(OldValue), OldValueTy), 305 M.makeLvalueToRvalue( 306 M.makeDereference( 307 M.makeLvalueToRvalue(M.makeDeclRefExpr(TheValue), TheValueTy), 308 PointeeTy), 309 PointeeTy), 310 BO_EQ); 311 312 // Construct the body of the IfStmt. 313 Stmt *Stmts[2]; 314 Stmts[0] = 315 M.makeAssignment( 316 M.makeDereference( 317 M.makeLvalueToRvalue(M.makeDeclRefExpr(TheValue), TheValueTy), 318 PointeeTy), 319 M.makeLvalueToRvalue(M.makeDeclRefExpr(NewValue), NewValueTy), 320 NewValueTy); 321 322 Expr *BoolVal = M.makeObjCBool(true); 323 Expr *RetVal = isBoolean ? M.makeIntegralCastToBoolean(BoolVal) 324 : M.makeIntegralCast(BoolVal, ResultTy); 325 Stmts[1] = M.makeReturn(RetVal); 326 CompoundStmt *Body = M.makeCompound(ArrayRef<Stmt*>(Stmts, 2)); 327 328 // Construct the else clause. 329 BoolVal = M.makeObjCBool(false); 330 RetVal = isBoolean ? M.makeIntegralCastToBoolean(BoolVal) 331 : M.makeIntegralCast(BoolVal, ResultTy); 332 Stmt *Else = M.makeReturn(RetVal); 333 334 /// Construct the If. 335 Stmt *If = 336 new (C) IfStmt(C, SourceLocation(), 0, Comparison, Body, 337 SourceLocation(), Else); 338 339 return If; 340} 341 342Stmt *BodyFarm::getBody(const FunctionDecl *D) { 343 D = D->getCanonicalDecl(); 344 345 llvm::Optional<Stmt *> &Val = Bodies[D]; 346 if (Val.hasValue()) 347 return Val.getValue(); 348 349 Val = 0; 350 351 if (D->getIdentifier() == 0) 352 return 0; 353 354 StringRef Name = D->getName(); 355 if (Name.empty()) 356 return 0; 357 358 FunctionFarmer FF; 359 360 if (Name.startswith("OSAtomicCompareAndSwap") || 361 Name.startswith("objc_atomicCompareAndSwap")) { 362 FF = create_OSAtomicCompareAndSwap; 363 } 364 else { 365 FF = llvm::StringSwitch<FunctionFarmer>(Name) 366 .Case("dispatch_sync", create_dispatch_sync) 367 .Case("dispatch_once", create_dispatch_once) 368 .Default(NULL); 369 } 370 371 if (FF) { Val = FF(C, D); } 372 return Val.getValue(); 373} 374 375