clang/lib/Analysis/ThreadSafetyCommon.cpp

   1 //===- ThreadSafetyCommon.cpp ---------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // Implementation of the interfaces declared in ThreadSafetyCommon.h
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "clang/Analysis/Analyses/ThreadSafetyCommon.h"
  14 #include "clang/AST/Attr.h"
  15 #include "clang/AST/Decl.h"
  16 #include "clang/AST/DeclCXX.h"
  17 #include "clang/AST/DeclGroup.h"
  18 #include "clang/AST/DeclObjC.h"
  19 #include "clang/AST/Expr.h"
  20 #include "clang/AST/ExprCXX.h"
  21 #include "clang/AST/OperationKinds.h"
  22 #include "clang/AST/Stmt.h"
  23 #include "clang/AST/Type.h"
  24 #include "clang/Analysis/Analyses/ThreadSafetyTIL.h"
  25 #include "clang/Analysis/CFG.h"
  26 #include "clang/Basic/LLVM.h"
  27 #include "clang/Basic/OperatorKinds.h"
  28 #include "clang/Basic/Specifiers.h"
  29 #include "llvm/ADT/StringExtras.h"
  30 #include "llvm/ADT/StringRef.h"
  31 #include "llvm/Support/Casting.h"
  32 #include <algorithm>
  33 #include <cassert>
  34 #include <string>
  35 #include <utility>
  36
  37 using namespace clang;
  38 using namespace threadSafety;
  39
  40 // From ThreadSafetyUtil.h
  41 std::string threadSafety::getSourceLiteralString(const Expr *CE) {
  42   switch (CE->getStmtClass()) {
  43     case Stmt::IntegerLiteralClass:
  44       return toString(cast<IntegerLiteral>(CE)->getValue(), 10, true);
  45     case Stmt::StringLiteralClass: {
  46       std::string ret("\"");
  47       ret += cast<StringLiteral>(CE)->getString();
  48       ret += "\"";
  49       return ret;
  50     }
  51     case Stmt::CharacterLiteralClass:
  52     case Stmt::CXXNullPtrLiteralExprClass:
  53     case Stmt::GNUNullExprClass:
  54     case Stmt::CXXBoolLiteralExprClass:
  55     case Stmt::FloatingLiteralClass:
  56     case Stmt::ImaginaryLiteralClass:
  57     case Stmt::ObjCStringLiteralClass:
  58     default:
  59       return "#lit";
  60   }
  61 }
  62
  63 // Return true if E is a variable that points to an incomplete Phi node.
  64 static bool isIncompletePhi(const til::SExpr *E) {
  65   if (const auto *Ph = dyn_cast<til::Phi>(E))
  66     return Ph->status() == til::Phi::PH_Incomplete;
  67   return false;
  68 }
  69
  70 using CallingContext = SExprBuilder::CallingContext;
  71
  72 til::SExpr *SExprBuilder::lookupStmt(const Stmt *S) {
  73   auto It = SMap.find(S);
  74   if (It != SMap.end())
  75     return It->second;
  76   return nullptr;
  77 }
  78
  79 til::SCFG *SExprBuilder::buildCFG(CFGWalker &Walker) {
  80   Walker.walk(*this);
  81   return Scfg;
  82 }
  83
  84 static bool isCalleeArrow(const Expr *E) {
  85   const auto *ME = dyn_cast<MemberExpr>(E->IgnoreParenCasts());
  86   return ME ? ME->isArrow() : false;
  87 }
  88
  89 static StringRef ClassifyDiagnostic(const CapabilityAttr *A) {
  90   return A->getName();
  91 }
  92
  93 static StringRef ClassifyDiagnostic(QualType VDT) {
  94   // We need to look at the declaration of the type of the value to determine
  95   // which it is. The type should either be a record or a typedef, or a pointer
  96   // or reference thereof.
  97   if (const auto *RT = VDT->getAs<RecordType>()) {
  98     if (const auto *RD = RT->getDecl())
  99       if (const auto *CA = RD->getAttr<CapabilityAttr>())
 100         return ClassifyDiagnostic(CA);
 101   } else if (const auto *TT = VDT->getAs<TypedefType>()) {
 102     if (const auto *TD = TT->getDecl())
 103       if (const auto *CA = TD->getAttr<CapabilityAttr>())
 104         return ClassifyDiagnostic(CA);
 105   } else if (VDT->isPointerType() || VDT->isReferenceType())
 106     return ClassifyDiagnostic(VDT->getPointeeType());
 107
 108   return "mutex";
 109 }
 110
 111 /// Translate a clang expression in an attribute to a til::SExpr.
 112 /// Constructs the context from D, DeclExp, and SelfDecl.
 113 ///
 114 /// \param AttrExp The expression to translate.
 115 /// \param D       The declaration to which the attribute is attached.
 116 /// \param DeclExp An expression involving the Decl to which the attribute
 117 ///                is attached.  E.g. the call to a function.
 118 /// \param Self    S-expression to substitute for a \ref CXXThisExpr.
 119 CapabilityExpr SExprBuilder::translateAttrExpr(const Expr *AttrExp,
 120                                                const NamedDecl *D,
 121                                                const Expr *DeclExp,
 122                                                til::SExpr *Self) {
 123   // If we are processing a raw attribute expression, with no substitutions.
 124   if (!DeclExp && !Self)
 125     return translateAttrExpr(AttrExp, nullptr);
 126
 127   CallingContext Ctx(nullptr, D);
 128
 129   // Examine DeclExp to find SelfArg and FunArgs, which are used to substitute
 130   // for formal parameters when we call buildMutexID later.
 131   if (!DeclExp)
 132     /* We'll use Self. */;
 133   else if (const auto *ME = dyn_cast<MemberExpr>(DeclExp)) {
 134     Ctx.SelfArg   = ME->getBase();
 135     Ctx.SelfArrow = ME->isArrow();
 136   } else if (const auto *CE = dyn_cast<CXXMemberCallExpr>(DeclExp)) {
 137     Ctx.SelfArg   = CE->getImplicitObjectArgument();
 138     Ctx.SelfArrow = isCalleeArrow(CE->getCallee());
 139     Ctx.NumArgs   = CE->getNumArgs();
 140     Ctx.FunArgs   = CE->getArgs();
 141   } else if (const auto *CE = dyn_cast<CallExpr>(DeclExp)) {
 142     Ctx.NumArgs = CE->getNumArgs();
 143     Ctx.FunArgs = CE->getArgs();
 144   } else if (const auto *CE = dyn_cast<CXXConstructExpr>(DeclExp)) {
 145     Ctx.SelfArg = nullptr;  // Will be set below
 146     Ctx.NumArgs = CE->getNumArgs();
 147     Ctx.FunArgs = CE->getArgs();
 148   }
 149
 150   if (Self) {
 151     assert(!Ctx.SelfArg && "Ambiguous self argument");
 152     Ctx.SelfArg = Self;
 153
 154     // If the attribute has no arguments, then assume the argument is "this".
 155     if (!AttrExp)
 156       return CapabilityExpr(
 157           Self, ClassifyDiagnostic(cast<CXXMethodDecl>(D)->getThisObjectType()),
 158           false);
 159     else  // For most attributes.
 160       return translateAttrExpr(AttrExp, &Ctx);
 161   }
 162
 163   // If the attribute has no arguments, then assume the argument is "this".
 164   if (!AttrExp)
 165     return translateAttrExpr(cast<const Expr *>(Ctx.SelfArg), nullptr);
 166   else  // For most attributes.
 167     return translateAttrExpr(AttrExp, &Ctx);
 168 }
 169
 170 /// Translate a clang expression in an attribute to a til::SExpr.
 171 // This assumes a CallingContext has already been created.
 172 CapabilityExpr SExprBuilder::translateAttrExpr(const Expr *AttrExp,
 173                                                CallingContext *Ctx) {
 174   if (!AttrExp)
 175     return CapabilityExpr();
 176
 177   if (const auto* SLit = dyn_cast<StringLiteral>(AttrExp)) {
 178     if (SLit->getString() == StringRef("*"))
 179       // The "*" expr is a universal lock, which essentially turns off
 180       // checks until it is removed from the lockset.
 181       return CapabilityExpr(new (Arena) til::Wildcard(), StringRef("wildcard"),
 182                             false);
 183     else
 184       // Ignore other string literals for now.
 185       return CapabilityExpr();
 186   }
 187
 188   bool Neg = false;
 189   if (const auto *OE = dyn_cast<CXXOperatorCallExpr>(AttrExp)) {
 190     if (OE->getOperator() == OO_Exclaim) {
 191       Neg = true;
 192       AttrExp = OE->getArg(0);
 193     }
 194   }
 195   else if (const auto *UO = dyn_cast<UnaryOperator>(AttrExp)) {
 196     if (UO->getOpcode() == UO_LNot) {
 197       Neg = true;
 198       AttrExp = UO->getSubExpr();
 199     }
 200   }
 201
 202   til::SExpr *E = translate(AttrExp, Ctx);
 203
 204   // Trap mutex expressions like nullptr, or 0.
 205   // Any literal value is nonsense.
 206   if (!E || isa<til::Literal>(E))
 207     return CapabilityExpr();
 208
 209   StringRef Kind = ClassifyDiagnostic(AttrExp->getType());
 210
 211   // Hack to deal with smart pointers -- strip off top-level pointer casts.
 212   if (const auto *CE = dyn_cast<til::Cast>(E)) {
 213     if (CE->castOpcode() == til::CAST_objToPtr)
 214       return CapabilityExpr(CE->expr(), Kind, Neg);
 215   }
 216   return CapabilityExpr(E, Kind, Neg);
 217 }
 218
 219 til::LiteralPtr *SExprBuilder::createVariable(const VarDecl *VD) {
 220   return new (Arena) til::LiteralPtr(VD);
 221 }
 222
 223 std::pair<til::LiteralPtr *, StringRef>
 224 SExprBuilder::createThisPlaceholder(const Expr *Exp) {
 225   return {new (Arena) til::LiteralPtr(nullptr),
 226           ClassifyDiagnostic(Exp->getType())};
 227 }
 228
 229 // Translate a clang statement or expression to a TIL expression.
 230 // Also performs substitution of variables; Ctx provides the context.
 231 // Dispatches on the type of S.
 232 til::SExpr *SExprBuilder::translate(const Stmt *S, CallingContext *Ctx) {
 233   if (!S)
 234     return nullptr;
 235
 236   // Check if S has already been translated and cached.
 237   // This handles the lookup of SSA names for DeclRefExprs here.
 238   if (til::SExpr *E = lookupStmt(S))
 239     return E;
 240
 241   switch (S->getStmtClass()) {
 242   case Stmt::DeclRefExprClass:
 243     return translateDeclRefExpr(cast<DeclRefExpr>(S), Ctx);
 244   case Stmt::CXXThisExprClass:
 245     return translateCXXThisExpr(cast<CXXThisExpr>(S), Ctx);
 246   case Stmt::MemberExprClass:
 247     return translateMemberExpr(cast<MemberExpr>(S), Ctx);
 248   case Stmt::ObjCIvarRefExprClass:
 249     return translateObjCIVarRefExpr(cast<ObjCIvarRefExpr>(S), Ctx);
 250   case Stmt::CallExprClass:
 251     return translateCallExpr(cast<CallExpr>(S), Ctx);
 252   case Stmt::CXXMemberCallExprClass:
 253     return translateCXXMemberCallExpr(cast<CXXMemberCallExpr>(S), Ctx);
 254   case Stmt::CXXOperatorCallExprClass:
 255     return translateCXXOperatorCallExpr(cast<CXXOperatorCallExpr>(S), Ctx);
 256   case Stmt::UnaryOperatorClass:
 257     return translateUnaryOperator(cast<UnaryOperator>(S), Ctx);
 258   case Stmt::BinaryOperatorClass:
 259   case Stmt::CompoundAssignOperatorClass:
 260     return translateBinaryOperator(cast<BinaryOperator>(S), Ctx);
 261
 262   case Stmt::ArraySubscriptExprClass:
 263     return translateArraySubscriptExpr(cast<ArraySubscriptExpr>(S), Ctx);
 264   case Stmt::ConditionalOperatorClass:
 265     return translateAbstractConditionalOperator(
 266              cast<ConditionalOperator>(S), Ctx);
 267   case Stmt::BinaryConditionalOperatorClass:
 268     return translateAbstractConditionalOperator(
 269              cast<BinaryConditionalOperator>(S), Ctx);
 270
 271   // We treat these as no-ops
 272   case Stmt::ConstantExprClass:
 273     return translate(cast<ConstantExpr>(S)->getSubExpr(), Ctx);
 274   case Stmt::ParenExprClass:
 275     return translate(cast<ParenExpr>(S)->getSubExpr(), Ctx);
 276   case Stmt::ExprWithCleanupsClass:
 277     return translate(cast<ExprWithCleanups>(S)->getSubExpr(), Ctx);
 278   case Stmt::CXXBindTemporaryExprClass:
 279     return translate(cast<CXXBindTemporaryExpr>(S)->getSubExpr(), Ctx);
 280   case Stmt::MaterializeTemporaryExprClass:
 281     return translate(cast<MaterializeTemporaryExpr>(S)->getSubExpr(), Ctx);
 282
 283   // Collect all literals
 284   case Stmt::CharacterLiteralClass:
 285   case Stmt::CXXNullPtrLiteralExprClass:
 286   case Stmt::GNUNullExprClass:
 287   case Stmt::CXXBoolLiteralExprClass:
 288   case Stmt::FloatingLiteralClass:
 289   case Stmt::ImaginaryLiteralClass:
 290   case Stmt::IntegerLiteralClass:
 291   case Stmt::StringLiteralClass:
 292   case Stmt::ObjCStringLiteralClass:
 293     return new (Arena) til::Literal(cast<Expr>(S));
 294
 295   case Stmt::DeclStmtClass:
 296     return translateDeclStmt(cast<DeclStmt>(S), Ctx);
 297   default:
 298     break;
 299   }
 300   if (const auto *CE = dyn_cast<CastExpr>(S))
 301     return translateCastExpr(CE, Ctx);
 302
 303   return new (Arena) til::Undefined(S);
 304 }
 305
 306 til::SExpr *SExprBuilder::translateDeclRefExpr(const DeclRefExpr *DRE,
 307                                                CallingContext *Ctx) {
 308   const auto *VD = cast<ValueDecl>(DRE->getDecl()->getCanonicalDecl());
 309
 310   // Function parameters require substitution and/or renaming.
 311   if (const auto *PV = dyn_cast<ParmVarDecl>(VD)) {
 312     unsigned I = PV->getFunctionScopeIndex();
 313     const DeclContext *D = PV->getDeclContext();
 314     if (Ctx && Ctx->FunArgs) {
 315       const Decl *Canonical = Ctx->AttrDecl->getCanonicalDecl();
 316       if (isa<FunctionDecl>(D)
 317               ? (cast<FunctionDecl>(D)->getCanonicalDecl() == Canonical)
 318               : (cast<ObjCMethodDecl>(D)->getCanonicalDecl() == Canonical)) {
 319         // Substitute call arguments for references to function parameters
 320         assert(I < Ctx->NumArgs);
 321         return translate(Ctx->FunArgs[I], Ctx->Prev);
 322       }
 323     }
 324     // Map the param back to the param of the original function declaration
 325     // for consistent comparisons.
 326     VD = isa<FunctionDecl>(D)
 327              ? cast<FunctionDecl>(D)->getCanonicalDecl()->getParamDecl(I)
 328              : cast<ObjCMethodDecl>(D)->getCanonicalDecl()->getParamDecl(I);
 329   }
 330
 331   // For non-local variables, treat it as a reference to a named object.
 332   return new (Arena) til::LiteralPtr(VD);
 333 }
 334
 335 til::SExpr *SExprBuilder::translateCXXThisExpr(const CXXThisExpr *TE,
 336                                                CallingContext *Ctx) {
 337   // Substitute for 'this'
 338   if (Ctx && Ctx->SelfArg) {
 339     if (const auto *SelfArg = dyn_cast<const Expr *>(Ctx->SelfArg))
 340       return translate(SelfArg, Ctx->Prev);
 341     else
 342       return cast<til::SExpr *>(Ctx->SelfArg);
 343   }
 344   assert(SelfVar && "We have no variable for 'this'!");
 345   return SelfVar;
 346 }
 347
 348 static const ValueDecl *getValueDeclFromSExpr(const til::SExpr *E) {
 349   if (const auto *V = dyn_cast<til::Variable>(E))
 350     return V->clangDecl();
 351   if (const auto *Ph = dyn_cast<til::Phi>(E))
 352     return Ph->clangDecl();
 353   if (const auto *P = dyn_cast<til::Project>(E))
 354     return P->clangDecl();
 355   if (const auto *L = dyn_cast<til::LiteralPtr>(E))
 356     return L->clangDecl();
 357   return nullptr;
 358 }
 359
 360 static bool hasAnyPointerType(const til::SExpr *E) {
 361   auto *VD = getValueDeclFromSExpr(E);
 362   if (VD && VD->getType()->isAnyPointerType())
 363     return true;
 364   if (const auto *C = dyn_cast<til::Cast>(E))
 365     return C->castOpcode() == til::CAST_objToPtr;
 366
 367   return false;
 368 }
 369
 370 // Grab the very first declaration of virtual method D
 371 static const CXXMethodDecl *getFirstVirtualDecl(const CXXMethodDecl *D) {
 372   while (true) {
 373     D = D->getCanonicalDecl();
 374     auto OverriddenMethods = D->overridden_methods();
 375     if (OverriddenMethods.begin() == OverriddenMethods.end())
 376       return D;  // Method does not override anything
 377     // FIXME: this does not work with multiple inheritance.
 378     D = *OverriddenMethods.begin();
 379   }
 380   return nullptr;
 381 }
 382
 383 til::SExpr *SExprBuilder::translateMemberExpr(const MemberExpr *ME,
 384                                               CallingContext *Ctx) {
 385   til::SExpr *BE = translate(ME->getBase(), Ctx);
 386   til::SExpr *E  = new (Arena) til::SApply(BE);
 387
 388   const auto *D = cast<ValueDecl>(ME->getMemberDecl()->getCanonicalDecl());
 389   if (const auto *VD = dyn_cast<CXXMethodDecl>(D))
 390     D = getFirstVirtualDecl(VD);
 391
 392   til::Project *P = new (Arena) til::Project(E, D);
 393   if (hasAnyPointerType(BE))
 394     P->setArrow(true);
 395   return P;
 396 }
 397
 398 til::SExpr *SExprBuilder::translateObjCIVarRefExpr(const ObjCIvarRefExpr *IVRE,
 399                                                    CallingContext *Ctx) {
 400   til::SExpr *BE = translate(IVRE->getBase(), Ctx);
 401   til::SExpr *E = new (Arena) til::SApply(BE);
 402
 403   const auto *D = cast<ObjCIvarDecl>(IVRE->getDecl()->getCanonicalDecl());
 404
 405   til::Project *P = new (Arena) til::Project(E, D);
 406   if (hasAnyPointerType(BE))
 407     P->setArrow(true);
 408   return P;
 409 }
 410
 411 til::SExpr *SExprBuilder::translateCallExpr(const CallExpr *CE,
 412                                             CallingContext *Ctx,
 413                                             const Expr *SelfE) {
 414   if (CapabilityExprMode) {
 415     // Handle LOCK_RETURNED
 416     if (const FunctionDecl *FD = CE->getDirectCallee()) {
 417       FD = FD->getMostRecentDecl();
 418       if (LockReturnedAttr *At = FD->getAttr<LockReturnedAttr>()) {
 419         CallingContext LRCallCtx(Ctx);
 420         LRCallCtx.AttrDecl = CE->getDirectCallee();
 421         LRCallCtx.SelfArg = SelfE;
 422         LRCallCtx.NumArgs = CE->getNumArgs();
 423         LRCallCtx.FunArgs = CE->getArgs();
 424         return const_cast<til::SExpr *>(
 425             translateAttrExpr(At->getArg(), &LRCallCtx).sexpr());
 426       }
 427     }
 428   }
 429
 430   til::SExpr *E = translate(CE->getCallee(), Ctx);
 431   for (const auto *Arg : CE->arguments()) {
 432     til::SExpr *A = translate(Arg, Ctx);
 433     E = new (Arena) til::Apply(E, A);
 434   }
 435   return new (Arena) til::Call(E, CE);
 436 }
 437
 438 til::SExpr *SExprBuilder::translateCXXMemberCallExpr(
 439     const CXXMemberCallExpr *ME, CallingContext *Ctx) {
 440   if (CapabilityExprMode) {
 441     // Ignore calls to get() on smart pointers.
 442     if (ME->getMethodDecl()->getNameAsString() == "get" &&
 443         ME->getNumArgs() == 0) {
 444       auto *E = translate(ME->getImplicitObjectArgument(), Ctx);
 445       return new (Arena) til::Cast(til::CAST_objToPtr, E);
 446       // return E;
 447     }
 448   }
 449   return translateCallExpr(cast<CallExpr>(ME), Ctx,
 450                            ME->getImplicitObjectArgument());
 451 }
 452
 453 til::SExpr *SExprBuilder::translateCXXOperatorCallExpr(
 454     const CXXOperatorCallExpr *OCE, CallingContext *Ctx) {
 455   if (CapabilityExprMode) {
 456     // Ignore operator * and operator -> on smart pointers.
 457     OverloadedOperatorKind k = OCE->getOperator();
 458     if (k == OO_Star || k == OO_Arrow) {
 459       auto *E = translate(OCE->getArg(0), Ctx);
 460       return new (Arena) til::Cast(til::CAST_objToPtr, E);
 461       // return E;
 462     }
 463   }
 464   return translateCallExpr(cast<CallExpr>(OCE), Ctx);
 465 }
 466
 467 til::SExpr *SExprBuilder::translateUnaryOperator(const UnaryOperator *UO,
 468                                                  CallingContext *Ctx) {
 469   switch (UO->getOpcode()) {
 470   case UO_PostInc:
 471   case UO_PostDec:
 472   case UO_PreInc:
 473   case UO_PreDec:
 474     return new (Arena) til::Undefined(UO);
 475
 476   case UO_AddrOf:
 477     if (CapabilityExprMode) {
 478       // interpret &Graph::mu_ as an existential.
 479       if (const auto *DRE = dyn_cast<DeclRefExpr>(UO->getSubExpr())) {
 480         if (DRE->getDecl()->isCXXInstanceMember()) {
 481           // This is a pointer-to-member expression, e.g. &MyClass::mu_.
 482           // We interpret this syntax specially, as a wildcard.
 483           auto *W = new (Arena) til::Wildcard();
 484           return new (Arena) til::Project(W, DRE->getDecl());
 485         }
 486       }
 487     }
 488     // otherwise, & is a no-op
 489     return translate(UO->getSubExpr(), Ctx);
 490
 491   // We treat these as no-ops
 492   case UO_Deref:
 493   case UO_Plus:
 494     return translate(UO->getSubExpr(), Ctx);
 495
 496   case UO_Minus:
 497     return new (Arena)
 498       til::UnaryOp(til::UOP_Minus, translate(UO->getSubExpr(), Ctx));
 499   case UO_Not:
 500     return new (Arena)
 501       til::UnaryOp(til::UOP_BitNot, translate(UO->getSubExpr(), Ctx));
 502   case UO_LNot:
 503     return new (Arena)
 504       til::UnaryOp(til::UOP_LogicNot, translate(UO->getSubExpr(), Ctx));
 505
 506   // Currently unsupported
 507   case UO_Real:
 508   case UO_Imag:
 509   case UO_Extension:
 510   case UO_Coawait:
 511     return new (Arena) til::Undefined(UO);
 512   }
 513   return new (Arena) til::Undefined(UO);
 514 }
 515
 516 til::SExpr *SExprBuilder::translateBinOp(til::TIL_BinaryOpcode Op,
 517                                          const BinaryOperator *BO,
 518                                          CallingContext *Ctx, bool Reverse) {
 519    til::SExpr *E0 = translate(BO->getLHS(), Ctx);
 520    til::SExpr *E1 = translate(BO->getRHS(), Ctx);
 521    if (Reverse)
 522      return new (Arena) til::BinaryOp(Op, E1, E0);
 523    else
 524      return new (Arena) til::BinaryOp(Op, E0, E1);
 525 }
 526
 527 til::SExpr *SExprBuilder::translateBinAssign(til::TIL_BinaryOpcode Op,
 528                                              const BinaryOperator *BO,
 529                                              CallingContext *Ctx,
 530                                              bool Assign) {
 531   const Expr *LHS = BO->getLHS();
 532   const Expr *RHS = BO->getRHS();
 533   til::SExpr *E0 = translate(LHS, Ctx);
 534   til::SExpr *E1 = translate(RHS, Ctx);
 535
 536   const ValueDecl *VD = nullptr;
 537   til::SExpr *CV = nullptr;
 538   if (const auto *DRE = dyn_cast<DeclRefExpr>(LHS)) {
 539     VD = DRE->getDecl();
 540     CV = lookupVarDecl(VD);
 541   }
 542
 543   if (!Assign) {
 544     til::SExpr *Arg = CV ? CV : new (Arena) til::Load(E0);
 545     E1 = new (Arena) til::BinaryOp(Op, Arg, E1);
 546     E1 = addStatement(E1, nullptr, VD);
 547   }
 548   if (VD && CV)
 549     return updateVarDecl(VD, E1);
 550   return new (Arena) til::Store(E0, E1);
 551 }
 552
 553 til::SExpr *SExprBuilder::translateBinaryOperator(const BinaryOperator *BO,
 554                                                   CallingContext *Ctx) {
 555   switch (BO->getOpcode()) {
 556   case BO_PtrMemD:
 557   case BO_PtrMemI:
 558     return new (Arena) til::Undefined(BO);
 559
 560   case BO_Mul:  return translateBinOp(til::BOP_Mul, BO, Ctx);
 561   case BO_Div:  return translateBinOp(til::BOP_Div, BO, Ctx);
 562   case BO_Rem:  return translateBinOp(til::BOP_Rem, BO, Ctx);
 563   case BO_Add:  return translateBinOp(til::BOP_Add, BO, Ctx);
 564   case BO_Sub:  return translateBinOp(til::BOP_Sub, BO, Ctx);
 565   case BO_Shl:  return translateBinOp(til::BOP_Shl, BO, Ctx);
 566   case BO_Shr:  return translateBinOp(til::BOP_Shr, BO, Ctx);
 567   case BO_LT:   return translateBinOp(til::BOP_Lt,  BO, Ctx);
 568   case BO_GT:   return translateBinOp(til::BOP_Lt,  BO, Ctx, true);
 569   case BO_LE:   return translateBinOp(til::BOP_Leq, BO, Ctx);
 570   case BO_GE:   return translateBinOp(til::BOP_Leq, BO, Ctx, true);
 571   case BO_EQ:   return translateBinOp(til::BOP_Eq,  BO, Ctx);
 572   case BO_NE:   return translateBinOp(til::BOP_Neq, BO, Ctx);
 573   case BO_Cmp:  return translateBinOp(til::BOP_Cmp, BO, Ctx);
 574   case BO_And:  return translateBinOp(til::BOP_BitAnd,   BO, Ctx);
 575   case BO_Xor:  return translateBinOp(til::BOP_BitXor,   BO, Ctx);
 576   case BO_Or:   return translateBinOp(til::BOP_BitOr,    BO, Ctx);
 577   case BO_LAnd: return translateBinOp(til::BOP_LogicAnd, BO, Ctx);
 578   case BO_LOr:  return translateBinOp(til::BOP_LogicOr,  BO, Ctx);
 579
 580   case BO_Assign:    return translateBinAssign(til::BOP_Eq,  BO, Ctx, true);
 581   case BO_MulAssign: return translateBinAssign(til::BOP_Mul, BO, Ctx);
 582   case BO_DivAssign: return translateBinAssign(til::BOP_Div, BO, Ctx);
 583   case BO_RemAssign: return translateBinAssign(til::BOP_Rem, BO, Ctx);
 584   case BO_AddAssign: return translateBinAssign(til::BOP_Add, BO, Ctx);
 585   case BO_SubAssign: return translateBinAssign(til::BOP_Sub, BO, Ctx);
 586   case BO_ShlAssign: return translateBinAssign(til::BOP_Shl, BO, Ctx);
 587   case BO_ShrAssign: return translateBinAssign(til::BOP_Shr, BO, Ctx);
 588   case BO_AndAssign: return translateBinAssign(til::BOP_BitAnd, BO, Ctx);
 589   case BO_XorAssign: return translateBinAssign(til::BOP_BitXor, BO, Ctx);
 590   case BO_OrAssign:  return translateBinAssign(til::BOP_BitOr,  BO, Ctx);
 591
 592   case BO_Comma:
 593     // The clang CFG should have already processed both sides.
 594     return translate(BO->getRHS(), Ctx);
 595   }
 596   return new (Arena) til::Undefined(BO);
 597 }
 598
 599 til::SExpr *SExprBuilder::translateCastExpr(const CastExpr *CE,
 600                                             CallingContext *Ctx) {
 601   CastKind K = CE->getCastKind();
 602   switch (K) {
 603   case CK_LValueToRValue: {
 604     if (const auto *DRE = dyn_cast<DeclRefExpr>(CE->getSubExpr())) {
 605       til::SExpr *E0 = lookupVarDecl(DRE->getDecl());
 606       if (E0)
 607         return E0;
 608     }
 609     til::SExpr *E0 = translate(CE->getSubExpr(), Ctx);
 610     return E0;
 611     // FIXME!! -- get Load working properly
 612     // return new (Arena) til::Load(E0);
 613   }
 614   case CK_NoOp:
 615   case CK_DerivedToBase:
 616   case CK_UncheckedDerivedToBase:
 617   case CK_ArrayToPointerDecay:
 618   case CK_FunctionToPointerDecay: {
 619     til::SExpr *E0 = translate(CE->getSubExpr(), Ctx);
 620     return E0;
 621   }
 622   default: {
 623     // FIXME: handle different kinds of casts.
 624     til::SExpr *E0 = translate(CE->getSubExpr(), Ctx);
 625     if (CapabilityExprMode)
 626       return E0;
 627     return new (Arena) til::Cast(til::CAST_none, E0);
 628   }
 629   }
 630 }
 631
 632 til::SExpr *
 633 SExprBuilder::translateArraySubscriptExpr(const ArraySubscriptExpr *E,
 634                                           CallingContext *Ctx) {
 635   til::SExpr *E0 = translate(E->getBase(), Ctx);
 636   til::SExpr *E1 = translate(E->getIdx(), Ctx);
 637   return new (Arena) til::ArrayIndex(E0, E1);
 638 }
 639
 640 til::SExpr *
 641 SExprBuilder::translateAbstractConditionalOperator(
 642     const AbstractConditionalOperator *CO, CallingContext *Ctx) {
 643   auto *C = translate(CO->getCond(), Ctx);
 644   auto *T = translate(CO->getTrueExpr(), Ctx);
 645   auto *E = translate(CO->getFalseExpr(), Ctx);
 646   return new (Arena) til::IfThenElse(C, T, E);
 647 }
 648
 649 til::SExpr *
 650 SExprBuilder::translateDeclStmt(const DeclStmt *S, CallingContext *Ctx) {
 651   DeclGroupRef DGrp = S->getDeclGroup();
 652   for (auto *I : DGrp) {
 653     if (auto *VD = dyn_cast_or_null<VarDecl>(I)) {
 654       Expr *E = VD->getInit();
 655       til::SExpr* SE = translate(E, Ctx);
 656
 657       // Add local variables with trivial type to the variable map
 658       QualType T = VD->getType();
 659       if (T.isTrivialType(VD->getASTContext()))
 660         return addVarDecl(VD, SE);
 661       else {
 662         // TODO: add alloca
 663       }
 664     }
 665   }
 666   return nullptr;
 667 }
 668
 669 // If (E) is non-trivial, then add it to the current basic block, and
 670 // update the statement map so that S refers to E.  Returns a new variable
 671 // that refers to E.
 672 // If E is trivial returns E.
 673 til::SExpr *SExprBuilder::addStatement(til::SExpr* E, const Stmt *S,
 674                                        const ValueDecl *VD) {
 675   if (!E || !CurrentBB || E->block() || til::ThreadSafetyTIL::isTrivial(E))
 676     return E;
 677   if (VD)
 678     E = new (Arena) til::Variable(E, VD);
 679   CurrentInstructions.push_back(E);
 680   if (S)
 681     insertStmt(S, E);
 682   return E;
 683 }
 684
 685 // Returns the current value of VD, if known, and nullptr otherwise.
 686 til::SExpr *SExprBuilder::lookupVarDecl(const ValueDecl *VD) {
 687   auto It = LVarIdxMap.find(VD);
 688   if (It != LVarIdxMap.end()) {
 689     assert(CurrentLVarMap[It->second].first == VD);
 690     return CurrentLVarMap[It->second].second;
 691   }
 692   return nullptr;
 693 }
 694
 695 // if E is a til::Variable, update its clangDecl.
 696 static void maybeUpdateVD(til::SExpr *E, const ValueDecl *VD) {
 697   if (!E)
 698     return;
 699   if (auto *V = dyn_cast<til::Variable>(E)) {
 700     if (!V->clangDecl())
 701       V->setClangDecl(VD);
 702   }
 703 }
 704
 705 // Adds a new variable declaration.
 706 til::SExpr *SExprBuilder::addVarDecl(const ValueDecl *VD, til::SExpr *E) {
 707   maybeUpdateVD(E, VD);
 708   LVarIdxMap.insert(std::make_pair(VD, CurrentLVarMap.size()));
 709   CurrentLVarMap.makeWritable();
 710   CurrentLVarMap.push_back(std::make_pair(VD, E));
 711   return E;
 712 }
 713
 714 // Updates a current variable declaration.  (E.g. by assignment)
 715 til::SExpr *SExprBuilder::updateVarDecl(const ValueDecl *VD, til::SExpr *E) {
 716   maybeUpdateVD(E, VD);
 717   auto It = LVarIdxMap.find(VD);
 718   if (It == LVarIdxMap.end()) {
 719     til::SExpr *Ptr = new (Arena) til::LiteralPtr(VD);
 720     til::SExpr *St  = new (Arena) til::Store(Ptr, E);
 721     return St;
 722   }
 723   CurrentLVarMap.makeWritable();
 724   CurrentLVarMap.elem(It->second).second = E;
 725   return E;
 726 }
 727
 728 // Make a Phi node in the current block for the i^th variable in CurrentVarMap.
 729 // If E != null, sets Phi[CurrentBlockInfo->ArgIndex] = E.
 730 // If E == null, this is a backedge and will be set later.
 731 void SExprBuilder::makePhiNodeVar(unsigned i, unsigned NPreds, til::SExpr *E) {
 732   unsigned ArgIndex = CurrentBlockInfo->ProcessedPredecessors;
 733   assert(ArgIndex > 0 && ArgIndex < NPreds);
 734
 735   til::SExpr *CurrE = CurrentLVarMap[i].second;
 736   if (CurrE->block() == CurrentBB) {
 737     // We already have a Phi node in the current block,
 738     // so just add the new variable to the Phi node.
 739     auto *Ph = dyn_cast<til::Phi>(CurrE);
 740     assert(Ph && "Expecting Phi node.");
 741     if (E)
 742       Ph->values()[ArgIndex] = E;
 743     return;
 744   }
 745
 746   // Make a new phi node: phi(..., E)
 747   // All phi args up to the current index are set to the current value.
 748   til::Phi *Ph = new (Arena) til::Phi(Arena, NPreds);
 749   Ph->values().setValues(NPreds, nullptr);
 750   for (unsigned PIdx = 0; PIdx < ArgIndex; ++PIdx)
 751     Ph->values()[PIdx] = CurrE;
 752   if (E)
 753     Ph->values()[ArgIndex] = E;
 754   Ph->setClangDecl(CurrentLVarMap[i].first);
 755   // If E is from a back-edge, or either E or CurrE are incomplete, then
 756   // mark this node as incomplete; we may need to remove it later.
 757   if (!E || isIncompletePhi(E) || isIncompletePhi(CurrE))
 758     Ph->setStatus(til::Phi::PH_Incomplete);
 759
 760   // Add Phi node to current block, and update CurrentLVarMap[i]
 761   CurrentArguments.push_back(Ph);
 762   if (Ph->status() == til::Phi::PH_Incomplete)
 763     IncompleteArgs.push_back(Ph);
 764
 765   CurrentLVarMap.makeWritable();
 766   CurrentLVarMap.elem(i).second = Ph;
 767 }
 768
 769 // Merge values from Map into the current variable map.
 770 // This will construct Phi nodes in the current basic block as necessary.
 771 void SExprBuilder::mergeEntryMap(LVarDefinitionMap Map) {
 772   assert(CurrentBlockInfo && "Not processing a block!");
 773
 774   if (!CurrentLVarMap.valid()) {
 775     // Steal Map, using copy-on-write.
 776     CurrentLVarMap = std::move(Map);
 777     return;
 778   }
 779   if (CurrentLVarMap.sameAs(Map))
 780     return;  // Easy merge: maps from different predecessors are unchanged.
 781
 782   unsigned NPreds = CurrentBB->numPredecessors();
 783   unsigned ESz = CurrentLVarMap.size();
 784   unsigned MSz = Map.size();
 785   unsigned Sz  = std::min(ESz, MSz);
 786
 787   for (unsigned i = 0; i < Sz; ++i) {
 788     if (CurrentLVarMap[i].first != Map[i].first) {
 789       // We've reached the end of variables in common.
 790       CurrentLVarMap.makeWritable();
 791       CurrentLVarMap.downsize(i);
 792       break;
 793     }
 794     if (CurrentLVarMap[i].second != Map[i].second)
 795       makePhiNodeVar(i, NPreds, Map[i].second);
 796   }
 797   if (ESz > MSz) {
 798     CurrentLVarMap.makeWritable();
 799     CurrentLVarMap.downsize(Map.size());
 800   }
 801 }
 802
 803 // Merge a back edge into the current variable map.
 804 // This will create phi nodes for all variables in the variable map.
 805 void SExprBuilder::mergeEntryMapBackEdge() {
 806   // We don't have definitions for variables on the backedge, because we
 807   // haven't gotten that far in the CFG.  Thus, when encountering a back edge,
 808   // we conservatively create Phi nodes for all variables.  Unnecessary Phi
 809   // nodes will be marked as incomplete, and stripped out at the end.
 810   //
 811   // An Phi node is unnecessary if it only refers to itself and one other
 812   // variable, e.g. x = Phi(y, y, x)  can be reduced to x = y.
 813
 814   assert(CurrentBlockInfo && "Not processing a block!");
 815
 816   if (CurrentBlockInfo->HasBackEdges)
 817     return;
 818   CurrentBlockInfo->HasBackEdges = true;
 819
 820   CurrentLVarMap.makeWritable();
 821   unsigned Sz = CurrentLVarMap.size();
 822   unsigned NPreds = CurrentBB->numPredecessors();
 823
 824   for (unsigned i = 0; i < Sz; ++i)
 825     makePhiNodeVar(i, NPreds, nullptr);
 826 }
 827
 828 // Update the phi nodes that were initially created for a back edge
 829 // once the variable definitions have been computed.
 830 // I.e., merge the current variable map into the phi nodes for Blk.
 831 void SExprBuilder::mergePhiNodesBackEdge(const CFGBlock *Blk) {
 832   til::BasicBlock *BB = lookupBlock(Blk);
 833   unsigned ArgIndex = BBInfo[Blk->getBlockID()].ProcessedPredecessors;
 834   assert(ArgIndex > 0 && ArgIndex < BB->numPredecessors());
 835
 836   for (til::SExpr *PE : BB->arguments()) {
 837     auto *Ph = dyn_cast_or_null<til::Phi>(PE);
 838     assert(Ph && "Expecting Phi Node.");
 839     assert(Ph->values()[ArgIndex] == nullptr && "Wrong index for back edge.");
 840
 841     til::SExpr *E = lookupVarDecl(Ph->clangDecl());
 842     assert(E && "Couldn't find local variable for Phi node.");
 843     Ph->values()[ArgIndex] = E;
 844   }
 845 }
 846
 847 void SExprBuilder::enterCFG(CFG *Cfg, const NamedDecl *D,
 848                             const CFGBlock *First) {
 849   // Perform initial setup operations.
 850   unsigned NBlocks = Cfg->getNumBlockIDs();
 851   Scfg = new (Arena) til::SCFG(Arena, NBlocks);
 852
 853   // allocate all basic blocks immediately, to handle forward references.
 854   BBInfo.resize(NBlocks);
 855   BlockMap.resize(NBlocks, nullptr);
 856   // create map from clang blockID to til::BasicBlocks
 857   for (auto *B : *Cfg) {
 858     auto *BB = new (Arena) til::BasicBlock(Arena);
 859     BB->reserveInstructions(B->size());
 860     BlockMap[B->getBlockID()] = BB;
 861   }
 862
 863   CurrentBB = lookupBlock(&Cfg->getEntry());
 864   auto Parms = isa<ObjCMethodDecl>(D) ? cast<ObjCMethodDecl>(D)->parameters()
 865                                       : cast<FunctionDecl>(D)->parameters();
 866   for (auto *Pm : Parms) {
 867     QualType T = Pm->getType();
 868     if (!T.isTrivialType(Pm->getASTContext()))
 869       continue;
 870
 871     // Add parameters to local variable map.
 872     // FIXME: right now we emulate params with loads; that should be fixed.
 873     til::SExpr *Lp = new (Arena) til::LiteralPtr(Pm);
 874     til::SExpr *Ld = new (Arena) til::Load(Lp);
 875     til::SExpr *V  = addStatement(Ld, nullptr, Pm);
 876     addVarDecl(Pm, V);
 877   }
 878 }
 879
 880 void SExprBuilder::enterCFGBlock(const CFGBlock *B) {
 881   // Initialize TIL basic block and add it to the CFG.
 882   CurrentBB = lookupBlock(B);
 883   CurrentBB->reservePredecessors(B->pred_size());
 884   Scfg->add(CurrentBB);
 885
 886   CurrentBlockInfo = &BBInfo[B->getBlockID()];
 887
 888   // CurrentLVarMap is moved to ExitMap on block exit.
 889   // FIXME: the entry block will hold function parameters.
 890   // assert(!CurrentLVarMap.valid() && "CurrentLVarMap already initialized.");
 891 }
 892
 893 void SExprBuilder::handlePredecessor(const CFGBlock *Pred) {
 894   // Compute CurrentLVarMap on entry from ExitMaps of predecessors
 895
 896   CurrentBB->addPredecessor(BlockMap[Pred->getBlockID()]);
 897   BlockInfo *PredInfo = &BBInfo[Pred->getBlockID()];
 898   assert(PredInfo->UnprocessedSuccessors > 0);
 899
 900   if (--PredInfo->UnprocessedSuccessors == 0)
 901     mergeEntryMap(std::move(PredInfo->ExitMap));
 902   else
 903     mergeEntryMap(PredInfo->ExitMap.clone());
 904
 905   ++CurrentBlockInfo->ProcessedPredecessors;
 906 }
 907
 908 void SExprBuilder::handlePredecessorBackEdge(const CFGBlock *Pred) {
 909   mergeEntryMapBackEdge();
 910 }
 911
 912 void SExprBuilder::enterCFGBlockBody(const CFGBlock *B) {
 913   // The merge*() methods have created arguments.
 914   // Push those arguments onto the basic block.
 915   CurrentBB->arguments().reserve(
 916     static_cast<unsigned>(CurrentArguments.size()), Arena);
 917   for (auto *A : CurrentArguments)
 918     CurrentBB->addArgument(A);
 919 }
 920
 921 void SExprBuilder::handleStatement(const Stmt *S) {
 922   til::SExpr *E = translate(S, nullptr);
 923   addStatement(E, S);
 924 }
 925
 926 void SExprBuilder::handleDestructorCall(const VarDecl *VD,
 927                                         const CXXDestructorDecl *DD) {
 928   til::SExpr *Sf = new (Arena) til::LiteralPtr(VD);
 929   til::SExpr *Dr = new (Arena) til::LiteralPtr(DD);
 930   til::SExpr *Ap = new (Arena) til::Apply(Dr, Sf);
 931   til::SExpr *E = new (Arena) til::Call(Ap);
 932   addStatement(E, nullptr);
 933 }
 934
 935 void SExprBuilder::exitCFGBlockBody(const CFGBlock *B) {
 936   CurrentBB->instructions().reserve(
 937     static_cast<unsigned>(CurrentInstructions.size()), Arena);
 938   for (auto *V : CurrentInstructions)
 939     CurrentBB->addInstruction(V);
 940
 941   // Create an appropriate terminator
 942   unsigned N = B->succ_size();
 943   auto It = B->succ_begin();
 944   if (N == 1) {
 945     til::BasicBlock *BB = *It ? lookupBlock(*It) : nullptr;
 946     // TODO: set index
 947     unsigned Idx = BB ? BB->findPredecessorIndex(CurrentBB) : 0;
 948     auto *Tm = new (Arena) til::Goto(BB, Idx);
 949     CurrentBB->setTerminator(Tm);
 950   }
 951   else if (N == 2) {
 952     til::SExpr *C = translate(B->getTerminatorCondition(true), nullptr);
 953     til::BasicBlock *BB1 = *It ? lookupBlock(*It) : nullptr;
 954     ++It;
 955     til::BasicBlock *BB2 = *It ? lookupBlock(*It) : nullptr;
 956     // FIXME: make sure these aren't critical edges.
 957     auto *Tm = new (Arena) til::Branch(C, BB1, BB2);
 958     CurrentBB->setTerminator(Tm);
 959   }
 960 }
 961
 962 void SExprBuilder::handleSuccessor(const CFGBlock *Succ) {
 963   ++CurrentBlockInfo->UnprocessedSuccessors;
 964 }
 965
 966 void SExprBuilder::handleSuccessorBackEdge(const CFGBlock *Succ) {
 967   mergePhiNodesBackEdge(Succ);
 968   ++BBInfo[Succ->getBlockID()].ProcessedPredecessors;
 969 }
 970
 971 void SExprBuilder::exitCFGBlock(const CFGBlock *B) {
 972   CurrentArguments.clear();
 973   CurrentInstructions.clear();
 974   CurrentBlockInfo->ExitMap = std::move(CurrentLVarMap);
 975   CurrentBB = nullptr;
 976   CurrentBlockInfo = nullptr;
 977 }
 978
 979 void SExprBuilder::exitCFG(const CFGBlock *Last) {
 980   for (auto *Ph : IncompleteArgs) {
 981     if (Ph->status() == til::Phi::PH_Incomplete)
 982       simplifyIncompleteArg(Ph);
 983   }
 984
 985   CurrentArguments.clear();
 986   CurrentInstructions.clear();
 987   IncompleteArgs.clear();
 988 }
 989
 990 /*
 991 namespace {
 992
 993 class TILPrinter :
 994     public til::PrettyPrinter<TILPrinter, llvm::raw_ostream> {};
 995
 996 } // namespace
 997
 998 namespace clang {
 999 namespace threadSafety {
1000
1001 void printSCFG(CFGWalker &Walker) {
1002   llvm::BumpPtrAllocator Bpa;
1003   til::MemRegionRef Arena(&Bpa);
1004   SExprBuilder SxBuilder(Arena);
1005   til::SCFG *Scfg = SxBuilder.buildCFG(Walker);
1006   TILPrinter::print(Scfg, llvm::errs());
1007 }
1008
1009 } // namespace threadSafety
1010 } // namespace clang
1011 */