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