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