1 //===- ThreadSafetyCommon.cpp ----------------------------------*- C++ --*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // 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/DeclCXX.h"
17 #include "clang/AST/ExprCXX.h"
18 #include "clang/AST/StmtCXX.h"
19 #include "clang/Analysis/Analyses/PostOrderCFGView.h"
20 #include "clang/Analysis/Analyses/ThreadSafetyTIL.h"
21 #include "clang/Analysis/Analyses/ThreadSafetyTraverse.h"
22 #include "clang/Analysis/AnalysisContext.h"
23 #include "clang/Analysis/CFG.h"
24 #include "clang/Basic/OperatorKinds.h"
25 #include "clang/Basic/SourceLocation.h"
26 #include "clang/Basic/SourceManager.h"
27 #include "llvm/ADT/DenseMap.h"
28 #include "llvm/ADT/SmallVector.h"
29 #include "llvm/ADT/StringRef.h"
30 
31 #include <algorithm>
32 #include <climits>
33 #include <vector>
34 
35 
36 namespace clang {
37 namespace threadSafety {
38 
39 namespace til {
40 
41 // If E is a variable, then trace back through any aliases or redundant
42 // Phi nodes to find the canonical definition.
43 SExpr *getCanonicalVal(SExpr *E) {
44   while (auto *V = dyn_cast<Variable>(E)) {
45     SExpr *D;
46     do {
47       if (V->kind() != Variable::VK_Let)
48         return V;
49       D = V->definition();
50       if (auto *V2 = dyn_cast<Variable>(D)) {
51         V = V2;
52         continue;
53       }
54     } while(false);
55 
56     if (ThreadSafetyTIL::isTrivial(D))
57       return D;
58 
59     if (Phi *Ph = dyn_cast<Phi>(D)) {
60       if (Ph->status() == Phi::PH_Incomplete)
61         simplifyIncompleteArg(V, Ph);
62 
63       if (Ph->status() == Phi::PH_SingleVal) {
64         E = Ph->values()[0];
65         continue;
66       }
67     }
68     return V;
69   }
70   return E;
71 }
72 
73 
74 // Trace the arguments of an incomplete Phi node to see if they have the same
75 // canonical definition.  If so, mark the Phi node as redundant.
76 // getCanonicalVal() will recursively call simplifyIncompletePhi().
77 void simplifyIncompleteArg(Variable *V, til::Phi *Ph) {
78   assert(!Ph && Ph->status() == Phi::PH_Incomplete);
79 
80   // eliminate infinite recursion -- assume that this node is not redundant.
81   Ph->setStatus(Phi::PH_MultiVal);
82 
83   SExpr *E0 = getCanonicalVal(Ph->values()[0]);
84   for (unsigned i=1, n=Ph->values().size(); i<n; ++i) {
85     SExpr *Ei = getCanonicalVal(Ph->values()[i]);
86     if (Ei == V)
87       continue;  // Recursive reference to itself.  Don't count.
88     if (Ei != E0) {
89       return;    // Status is already set to MultiVal.
90     }
91   }
92   Ph->setStatus(Phi::PH_SingleVal);
93 }
94 
95 }  // end namespace til
96 
97 
98 typedef SExprBuilder::CallingContext CallingContext;
99 
100 
101 til::SExpr *SExprBuilder::lookupStmt(const Stmt *S) {
102   auto It = SMap.find(S);
103   if (It != SMap.end())
104     return It->second;
105   return nullptr;
106 }
107 
108 
109 til::SCFG *SExprBuilder::buildCFG(CFGWalker &Walker) {
110   Walker.walk(*this);
111   return Scfg;
112 }
113 
114 
115 // Translate a clang statement or expression to a TIL expression.
116 // Also performs substitution of variables; Ctx provides the context.
117 // Dispatches on the type of S.
118 til::SExpr *SExprBuilder::translate(const Stmt *S, CallingContext *Ctx) {
119   if (!S)
120     return nullptr;
121 
122   // Check if S has already been translated and cached.
123   // This handles the lookup of SSA names for DeclRefExprs here.
124   if (til::SExpr *E = lookupStmt(S))
125     return E;
126 
127   switch (S->getStmtClass()) {
128   case Stmt::DeclRefExprClass:
129     return translateDeclRefExpr(cast<DeclRefExpr>(S), Ctx);
130   case Stmt::CXXThisExprClass:
131     return translateCXXThisExpr(cast<CXXThisExpr>(S), Ctx);
132   case Stmt::MemberExprClass:
133     return translateMemberExpr(cast<MemberExpr>(S), Ctx);
134   case Stmt::CallExprClass:
135     return translateCallExpr(cast<CallExpr>(S), Ctx);
136   case Stmt::CXXMemberCallExprClass:
137     return translateCXXMemberCallExpr(cast<CXXMemberCallExpr>(S), Ctx);
138   case Stmt::CXXOperatorCallExprClass:
139     return translateCXXOperatorCallExpr(cast<CXXOperatorCallExpr>(S), Ctx);
140   case Stmt::UnaryOperatorClass:
141     return translateUnaryOperator(cast<UnaryOperator>(S), Ctx);
142   case Stmt::BinaryOperatorClass:
143     return translateBinaryOperator(cast<BinaryOperator>(S), Ctx);
144 
145   case Stmt::ArraySubscriptExprClass:
146     return translateArraySubscriptExpr(cast<ArraySubscriptExpr>(S), Ctx);
147   case Stmt::ConditionalOperatorClass:
148     return translateConditionalOperator(cast<ConditionalOperator>(S), Ctx);
149   case Stmt::BinaryConditionalOperatorClass:
150     return translateBinaryConditionalOperator(
151              cast<BinaryConditionalOperator>(S), Ctx);
152 
153   // We treat these as no-ops
154   case Stmt::ParenExprClass:
155     return translate(cast<ParenExpr>(S)->getSubExpr(), Ctx);
156   case Stmt::ExprWithCleanupsClass:
157     return translate(cast<ExprWithCleanups>(S)->getSubExpr(), Ctx);
158   case Stmt::CXXBindTemporaryExprClass:
159     return translate(cast<CXXBindTemporaryExpr>(S)->getSubExpr(), Ctx);
160 
161   // Collect all literals
162   case Stmt::CharacterLiteralClass:
163   case Stmt::CXXNullPtrLiteralExprClass:
164   case Stmt::GNUNullExprClass:
165   case Stmt::CXXBoolLiteralExprClass:
166   case Stmt::FloatingLiteralClass:
167   case Stmt::ImaginaryLiteralClass:
168   case Stmt::IntegerLiteralClass:
169   case Stmt::StringLiteralClass:
170   case Stmt::ObjCStringLiteralClass:
171     return new (Arena) til::Literal(cast<Expr>(S));
172 
173   case Stmt::DeclStmtClass:
174     return translateDeclStmt(cast<DeclStmt>(S), Ctx);
175   default:
176     break;
177   }
178   if (const CastExpr *CE = dyn_cast<CastExpr>(S))
179     return translateCastExpr(CE, Ctx);
180 
181   return new (Arena) til::Undefined(S);
182 }
183 
184 
185 til::SExpr *SExprBuilder::translateDeclRefExpr(const DeclRefExpr *DRE,
186                                                CallingContext *Ctx) {
187   const ValueDecl *VD = cast<ValueDecl>(DRE->getDecl()->getCanonicalDecl());
188 
189   // Function parameters require substitution and/or renaming.
190   if (const ParmVarDecl *PV = dyn_cast_or_null<ParmVarDecl>(VD)) {
191     const FunctionDecl *FD =
192         cast<FunctionDecl>(PV->getDeclContext())->getCanonicalDecl();
193     unsigned I = PV->getFunctionScopeIndex();
194 
195     if (Ctx && Ctx->FunArgs && FD == Ctx->AttrDecl->getCanonicalDecl()) {
196       // Substitute call arguments for references to function parameters
197       assert(I < Ctx->NumArgs);
198       return translate(Ctx->FunArgs[I], Ctx->Prev);
199     }
200     // Map the param back to the param of the original function declaration
201     // for consistent comparisons.
202     VD = FD->getParamDecl(I);
203   }
204 
205   // For non-local variables, treat it as a referenced to a named object.
206   return new (Arena) til::LiteralPtr(VD);
207 }
208 
209 
210 til::SExpr *SExprBuilder::translateCXXThisExpr(const CXXThisExpr *TE,
211                                                CallingContext *Ctx) {
212   // Substitute for 'this'
213   if (Ctx && Ctx->SelfArg)
214     return translate(Ctx->SelfArg, Ctx->Prev);
215   assert(SelfVar && "We have no variable for 'this'!");
216   return SelfVar;
217 }
218 
219 
220 til::SExpr *SExprBuilder::translateMemberExpr(const MemberExpr *ME,
221                                               CallingContext *Ctx) {
222   til::SExpr *E = translate(ME->getBase(), Ctx);
223   E = new (Arena) til::SApply(E);
224   return new (Arena) til::Project(E, ME->getMemberDecl());
225 }
226 
227 
228 til::SExpr *SExprBuilder::translateCallExpr(const CallExpr *CE,
229                                             CallingContext *Ctx) {
230   // TODO -- Lock returned
231   til::SExpr *E = translate(CE->getCallee(), Ctx);
232   for (const auto *Arg : CE->arguments()) {
233     til::SExpr *A = translate(Arg, Ctx);
234     E = new (Arena) til::Apply(E, A);
235   }
236   return new (Arena) til::Call(E, CE);
237 }
238 
239 
240 til::SExpr *SExprBuilder::translateCXXMemberCallExpr(
241     const CXXMemberCallExpr *ME, CallingContext *Ctx) {
242   return translateCallExpr(cast<CallExpr>(ME), Ctx);
243 }
244 
245 
246 til::SExpr *SExprBuilder::translateCXXOperatorCallExpr(
247     const CXXOperatorCallExpr *OCE, CallingContext *Ctx) {
248   return translateCallExpr(cast<CallExpr>(OCE), Ctx);
249 }
250 
251 
252 til::SExpr *SExprBuilder::translateUnaryOperator(const UnaryOperator *UO,
253                                                  CallingContext *Ctx) {
254   switch (UO->getOpcode()) {
255   case UO_PostInc:
256   case UO_PostDec:
257   case UO_PreInc:
258   case UO_PreDec:
259     return new (Arena) til::Undefined(UO);
260 
261   // We treat these as no-ops
262   case UO_AddrOf:
263   case UO_Deref:
264   case UO_Plus:
265     return translate(UO->getSubExpr(), Ctx);
266 
267   case UO_Minus:
268   case UO_Not:
269   case UO_LNot:
270   case UO_Real:
271   case UO_Imag:
272   case UO_Extension:
273     return new (Arena)
274         til::UnaryOp(UO->getOpcode(), translate(UO->getSubExpr(), Ctx));
275   }
276   return new (Arena) til::Undefined(UO);
277 }
278 
279 
280 til::SExpr *SExprBuilder::translateBinaryOperator(const BinaryOperator *BO,
281                                                   CallingContext *Ctx) {
282   switch (BO->getOpcode()) {
283   case BO_PtrMemD:
284   case BO_PtrMemI:
285     return new (Arena) til::Undefined(BO);
286 
287   case BO_Mul:
288   case BO_Div:
289   case BO_Rem:
290   case BO_Add:
291   case BO_Sub:
292   case BO_Shl:
293   case BO_Shr:
294   case BO_LT:
295   case BO_GT:
296   case BO_LE:
297   case BO_GE:
298   case BO_EQ:
299   case BO_NE:
300   case BO_And:
301   case BO_Xor:
302   case BO_Or:
303   case BO_LAnd:
304   case BO_LOr:
305     return new (Arena)
306         til::BinaryOp(BO->getOpcode(), translate(BO->getLHS(), Ctx),
307                       translate(BO->getRHS(), Ctx));
308 
309   case BO_Assign: {
310     const Expr *LHS = BO->getLHS();
311     if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(LHS)) {
312       const Expr *RHS = BO->getRHS();
313       til::SExpr *E1 = translate(RHS, Ctx);
314       return updateVarDecl(DRE->getDecl(), E1);
315     }
316     til::SExpr *E0 = translate(LHS, Ctx);
317     til::SExpr *E1 = translate(BO->getRHS(), Ctx);
318     return new (Arena) til::Store(E0, E1);
319   }
320   case BO_MulAssign:
321   case BO_DivAssign:
322   case BO_RemAssign:
323   case BO_AddAssign:
324   case BO_SubAssign:
325   case BO_ShlAssign:
326   case BO_ShrAssign:
327   case BO_AndAssign:
328   case BO_XorAssign:
329   case BO_OrAssign:
330     return new (Arena) til::Undefined(BO);
331 
332   case BO_Comma:
333     // TODO: handle LHS
334     return translate(BO->getRHS(), Ctx);
335   }
336 
337   return new (Arena) til::Undefined(BO);
338 }
339 
340 
341 til::SExpr *SExprBuilder::translateCastExpr(const CastExpr *CE,
342                                             CallingContext *Ctx) {
343   clang::CastKind K = CE->getCastKind();
344   switch (K) {
345   case CK_LValueToRValue: {
346     if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(CE->getSubExpr())) {
347       til::SExpr *E0 = lookupVarDecl(DRE->getDecl());
348       if (E0)
349         return E0;
350     }
351     til::SExpr *E0 = translate(CE->getSubExpr(), Ctx);
352     return new (Arena) til::Load(E0);
353   }
354   case CK_NoOp:
355   case CK_DerivedToBase:
356   case CK_UncheckedDerivedToBase:
357   case CK_ArrayToPointerDecay:
358   case CK_FunctionToPointerDecay: {
359     til::SExpr *E0 = translate(CE->getSubExpr(), Ctx);
360     return E0;
361   }
362   default: {
363     til::SExpr *E0 = translate(CE->getSubExpr(), Ctx);
364     return new (Arena) til::Cast(K, E0);
365   }
366   }
367 }
368 
369 
370 til::SExpr *
371 SExprBuilder::translateArraySubscriptExpr(const ArraySubscriptExpr *E,
372                                           CallingContext *Ctx) {
373   return new (Arena) til::Undefined(E);
374 }
375 
376 
377 til::SExpr *
378 SExprBuilder::translateConditionalOperator(const ConditionalOperator *C,
379                                            CallingContext *Ctx) {
380   return new (Arena) til::Undefined(C);
381 }
382 
383 
384 til::SExpr *SExprBuilder::translateBinaryConditionalOperator(
385     const BinaryConditionalOperator *C, CallingContext *Ctx) {
386   return new (Arena) til::Undefined(C);
387 }
388 
389 
390 til::SExpr *
391 SExprBuilder::translateDeclStmt(const DeclStmt *S, CallingContext *Ctx) {
392   DeclGroupRef DGrp = S->getDeclGroup();
393   for (DeclGroupRef::iterator I = DGrp.begin(), E = DGrp.end(); I != E; ++I) {
394     if (VarDecl *VD = dyn_cast_or_null<VarDecl>(*I)) {
395       Expr *E = VD->getInit();
396       til::SExpr* SE = translate(E, Ctx);
397 
398       // Add local variables with trivial type to the variable map
399       QualType T = VD->getType();
400       if (T.isTrivialType(VD->getASTContext())) {
401         return addVarDecl(VD, SE);
402       }
403       else {
404         // TODO: add alloca
405       }
406     }
407   }
408   return nullptr;
409 }
410 
411 
412 
413 // If (E) is non-trivial, then add it to the current basic block, and
414 // update the statement map so that S refers to E.  Returns a new variable
415 // that refers to E.
416 // If E is trivial returns E.
417 til::SExpr *SExprBuilder::addStatement(til::SExpr* E, const Stmt *S,
418                                        const ValueDecl *VD) {
419   if (!E)
420     return nullptr;
421   if (til::ThreadSafetyTIL::isTrivial(E))
422     return E;
423 
424   til::Variable *V = new (Arena) til::Variable(E, VD);
425   CurrentInstructions.push_back(V);
426   if (S)
427     insertStmt(S, V);
428   return V;
429 }
430 
431 
432 // Returns the current value of VD, if known, and nullptr otherwise.
433 til::SExpr *SExprBuilder::lookupVarDecl(const ValueDecl *VD) {
434   auto It = LVarIdxMap.find(VD);
435   if (It != LVarIdxMap.end()) {
436     assert(CurrentLVarMap[It->second].first == VD);
437     return CurrentLVarMap[It->second].second;
438   }
439   return nullptr;
440 }
441 
442 
443 // if E is a til::Variable, update its clangDecl.
444 inline void maybeUpdateVD(til::SExpr *E, const ValueDecl *VD) {
445   if (!E)
446     return;
447   if (til::Variable *V = dyn_cast<til::Variable>(E)) {
448     if (!V->clangDecl())
449       V->setClangDecl(VD);
450   }
451 }
452 
453 // Adds a new variable declaration.
454 til::SExpr *SExprBuilder::addVarDecl(const ValueDecl *VD, til::SExpr *E) {
455   maybeUpdateVD(E, VD);
456   LVarIdxMap.insert(std::make_pair(VD, CurrentLVarMap.size()));
457   CurrentLVarMap.makeWritable();
458   CurrentLVarMap.push_back(std::make_pair(VD, E));
459   return E;
460 }
461 
462 
463 // Updates a current variable declaration.  (E.g. by assignment)
464 til::SExpr *SExprBuilder::updateVarDecl(const ValueDecl *VD, til::SExpr *E) {
465   maybeUpdateVD(E, VD);
466   auto It = LVarIdxMap.find(VD);
467   if (It == LVarIdxMap.end()) {
468     til::SExpr *Ptr = new (Arena) til::LiteralPtr(VD);
469     til::SExpr *St  = new (Arena) til::Store(Ptr, E);
470     return St;
471   }
472   CurrentLVarMap.makeWritable();
473   CurrentLVarMap.elem(It->second).second = E;
474   return E;
475 }
476 
477 
478 // Make a Phi node in the current block for the i^th variable in CurrentVarMap.
479 // If E != null, sets Phi[CurrentBlockInfo->ArgIndex] = E.
480 // If E == null, this is a backedge and will be set later.
481 void SExprBuilder::makePhiNodeVar(unsigned i, unsigned NPreds, til::SExpr *E) {
482   unsigned ArgIndex = CurrentBlockInfo->ProcessedPredecessors;
483   assert(ArgIndex > 0 && ArgIndex < NPreds);
484 
485   til::Variable *V = dyn_cast<til::Variable>(CurrentLVarMap[i].second);
486   if (V && V->getBlockID() == CurrentBB->blockID()) {
487     // We already have a Phi node in the current block,
488     // so just add the new variable to the Phi node.
489     til::Phi *Ph = dyn_cast<til::Phi>(V->definition());
490     assert(Ph && "Expecting Phi node.");
491     if (E)
492       Ph->values()[ArgIndex] = E;
493     return;
494   }
495 
496   // Make a new phi node: phi(..., E)
497   // All phi args up to the current index are set to the current value.
498   til::Phi *Ph = new (Arena) til::Phi(Arena, NPreds);
499   Ph->values().setValues(NPreds, nullptr);
500   for (unsigned PIdx = 0; PIdx < ArgIndex; ++PIdx)
501     Ph->values()[PIdx] = CurrentLVarMap[i].second;
502   if (E)
503     Ph->values()[ArgIndex] = E;
504   if (!E) {
505     // This is a non-minimal SSA node, which may be removed later.
506     Ph->setStatus(til::Phi::PH_Incomplete);
507   }
508 
509   // Add Phi node to current block, and update CurrentLVarMap[i]
510   auto *Var = new (Arena) til::Variable(Ph, CurrentLVarMap[i].first);
511   CurrentArguments.push_back(Var);
512   if (Ph->status() == til::Phi::PH_Incomplete)
513     IncompleteArgs.push_back(Var);
514 
515   CurrentLVarMap.makeWritable();
516   CurrentLVarMap.elem(i).second = Var;
517 }
518 
519 
520 // Merge values from Map into the current variable map.
521 // This will construct Phi nodes in the current basic block as necessary.
522 void SExprBuilder::mergeEntryMap(LVarDefinitionMap Map) {
523   assert(CurrentBlockInfo && "Not processing a block!");
524 
525   if (!CurrentLVarMap.valid()) {
526     // Steal Map, using copy-on-write.
527     CurrentLVarMap = std::move(Map);
528     return;
529   }
530   if (CurrentLVarMap.sameAs(Map))
531     return;  // Easy merge: maps from different predecessors are unchanged.
532 
533   unsigned NPreds = CurrentBB->numPredecessors();
534   unsigned ESz = CurrentLVarMap.size();
535   unsigned MSz = Map.size();
536   unsigned Sz  = std::min(ESz, MSz);
537 
538   for (unsigned i=0; i<Sz; ++i) {
539     if (CurrentLVarMap[i].first != Map[i].first) {
540       // We've reached the end of variables in common.
541       CurrentLVarMap.makeWritable();
542       CurrentLVarMap.downsize(i);
543       break;
544     }
545     if (CurrentLVarMap[i].second != Map[i].second)
546       makePhiNodeVar(i, NPreds, Map[i].second);
547   }
548   if (ESz > MSz) {
549     CurrentLVarMap.makeWritable();
550     CurrentLVarMap.downsize(Map.size());
551   }
552 }
553 
554 
555 // Merge a back edge into the current variable map.
556 // This will create phi nodes for all variables in the variable map.
557 void SExprBuilder::mergeEntryMapBackEdge() {
558   // We don't have definitions for variables on the backedge, because we
559   // haven't gotten that far in the CFG.  Thus, when encountering a back edge,
560   // we conservatively create Phi nodes for all variables.  Unnecessary Phi
561   // nodes will be marked as incomplete, and stripped out at the end.
562   //
563   // An Phi node is unnecessary if it only refers to itself and one other
564   // variable, e.g. x = Phi(y, y, x)  can be reduced to x = y.
565 
566   assert(CurrentBlockInfo && "Not processing a block!");
567 
568   if (CurrentBlockInfo->HasBackEdges)
569     return;
570   CurrentBlockInfo->HasBackEdges = true;
571 
572   CurrentLVarMap.makeWritable();
573   unsigned Sz = CurrentLVarMap.size();
574   unsigned NPreds = CurrentBB->numPredecessors();
575 
576   for (unsigned i=0; i < Sz; ++i) {
577     makePhiNodeVar(i, NPreds, nullptr);
578   }
579 }
580 
581 
582 // Update the phi nodes that were initially created for a back edge
583 // once the variable definitions have been computed.
584 // I.e., merge the current variable map into the phi nodes for Blk.
585 void SExprBuilder::mergePhiNodesBackEdge(const CFGBlock *Blk) {
586   til::BasicBlock *BB = lookupBlock(Blk);
587   unsigned ArgIndex = BBInfo[Blk->getBlockID()].ProcessedPredecessors;
588   assert(ArgIndex > 0 && ArgIndex < BB->numPredecessors());
589 
590   for (til::Variable *V : BB->arguments()) {
591     til::Phi *Ph = dyn_cast_or_null<til::Phi>(V->definition());
592     assert(Ph && "Expecting Phi Node.");
593     assert(Ph->values()[ArgIndex] == nullptr && "Wrong index for back edge.");
594     assert(V->clangDecl() && "No local variable for Phi node.");
595 
596     til::SExpr *E = lookupVarDecl(V->clangDecl());
597     assert(E && "Couldn't find local variable for Phi node.");
598 
599     Ph->values()[ArgIndex] = E;
600   }
601 }
602 
603 
604 
605 void SExprBuilder::enterCFG(CFG *Cfg, const NamedDecl *D,
606                             const CFGBlock *First) {
607   // Perform initial setup operations.
608   unsigned NBlocks = Cfg->getNumBlockIDs();
609   Scfg = new (Arena) til::SCFG(Arena, NBlocks);
610 
611   // allocate all basic blocks immediately, to handle forward references.
612   BBInfo.resize(NBlocks);
613   BlockMap.resize(NBlocks, nullptr);
614   // create map from clang blockID to til::BasicBlocks
615   for (auto *B : *Cfg) {
616     auto *BB = new (Arena) til::BasicBlock(Arena, 0, B->size());
617     BlockMap[B->getBlockID()] = BB;
618   }
619   CallCtx = new SExprBuilder::CallingContext(D);
620 }
621 
622 
623 void SExprBuilder::enterCFGBlock(const CFGBlock *B) {
624   // Intialize TIL basic block and add it to the CFG.
625   CurrentBB = BlockMap[B->getBlockID()];
626   CurrentBB->setNumPredecessors(B->pred_size());
627   Scfg->add(CurrentBB);
628 
629   CurrentBlockInfo = &BBInfo[B->getBlockID()];
630   CurrentArguments.clear();
631   CurrentInstructions.clear();
632 
633   // CurrentLVarMap is moved to ExitMap on block exit.
634   assert(!CurrentLVarMap.valid() && "CurrentLVarMap already initialized.");
635 }
636 
637 
638 void SExprBuilder::handlePredecessor(const CFGBlock *Pred) {
639   // Compute CurrentLVarMap on entry from ExitMaps of predecessors
640 
641   BlockInfo *PredInfo = &BBInfo[Pred->getBlockID()];
642   assert(PredInfo->UnprocessedSuccessors > 0);
643 
644   if (--PredInfo->UnprocessedSuccessors == 0)
645     mergeEntryMap(std::move(PredInfo->ExitMap));
646   else
647     mergeEntryMap(PredInfo->ExitMap.clone());
648 
649   ++CurrentBlockInfo->ProcessedPredecessors;
650 }
651 
652 
653 void SExprBuilder::handlePredecessorBackEdge(const CFGBlock *Pred) {
654   mergeEntryMapBackEdge();
655 }
656 
657 
658 void SExprBuilder::enterCFGBlockBody(const CFGBlock *B) {
659   // The merge*() methods have created arguments.
660   // Push those arguments onto the basic block.
661   CurrentBB->arguments().reserve(
662     static_cast<unsigned>(CurrentArguments.size()), Arena);
663   for (auto *V : CurrentArguments)
664     CurrentBB->addArgument(V);
665 }
666 
667 
668 void SExprBuilder::handleStatement(const Stmt *S) {
669   til::SExpr *E = translate(S, CallCtx);
670   addStatement(E, S);
671 }
672 
673 
674 void SExprBuilder::handleDestructorCall(const VarDecl *VD,
675                                         const CXXDestructorDecl *DD) {
676   til::SExpr *Sf = new (Arena) til::LiteralPtr(VD);
677   til::SExpr *Dr = new (Arena) til::LiteralPtr(DD);
678   til::SExpr *Ap = new (Arena) til::Apply(Dr, Sf);
679   til::SExpr *E = new (Arena) til::Call(Ap);
680   addStatement(E, nullptr);
681 }
682 
683 
684 
685 void SExprBuilder::exitCFGBlockBody(const CFGBlock *B) {
686   CurrentBB->instructions().reserve(
687     static_cast<unsigned>(CurrentInstructions.size()), Arena);
688   for (auto *V : CurrentInstructions)
689     CurrentBB->addInstruction(V);
690 
691   // Create an appropriate terminator
692   unsigned N = B->succ_size();
693   auto It = B->succ_begin();
694   if (N == 1) {
695     til::BasicBlock *BB = *It ? lookupBlock(*It) : nullptr;
696     // TODO: set index
697     til::SExpr *Tm = new (Arena) til::Goto(BB, 0);
698     CurrentBB->setTerminator(Tm);
699   }
700   else if (N == 2) {
701     til::SExpr *C = translate(B->getTerminatorCondition(true), CallCtx);
702     til::BasicBlock *BB1 = *It ? lookupBlock(*It) : nullptr;
703     ++It;
704     til::BasicBlock *BB2 = *It ? lookupBlock(*It) : nullptr;
705     // TODO: set conditional, set index
706     til::SExpr *Tm = new (Arena) til::Branch(C, BB1, BB2);
707     CurrentBB->setTerminator(Tm);
708   }
709 }
710 
711 
712 void SExprBuilder::handleSuccessor(const CFGBlock *Succ) {
713   ++CurrentBlockInfo->UnprocessedSuccessors;
714 }
715 
716 
717 void SExprBuilder::handleSuccessorBackEdge(const CFGBlock *Succ) {
718   mergePhiNodesBackEdge(Succ);
719   ++BBInfo[Succ->getBlockID()].ProcessedPredecessors;
720 }
721 
722 
723 void SExprBuilder::exitCFGBlock(const CFGBlock *B) {
724   CurrentBlockInfo->ExitMap = std::move(CurrentLVarMap);
725   CurrentBB = nullptr;
726   CurrentBlockInfo = nullptr;
727 }
728 
729 
730 void SExprBuilder::exitCFG(const CFGBlock *Last) {
731   for (auto *V : IncompleteArgs) {
732     til::Phi *Ph = dyn_cast<til::Phi>(V->definition());
733     if (Ph && Ph->status() == til::Phi::PH_Incomplete)
734       simplifyIncompleteArg(V, Ph);
735   }
736 
737   CurrentArguments.clear();
738   CurrentInstructions.clear();
739   IncompleteArgs.clear();
740 }
741 
742 
743 
744 class LLVMPrinter : public til::PrettyPrinter<LLVMPrinter, llvm::raw_ostream> {
745 };
746 
747 
748 void printSCFG(CFGWalker &Walker) {
749   llvm::BumpPtrAllocator Bpa;
750   til::MemRegionRef Arena(&Bpa);
751   SExprBuilder builder(Arena);
752   til::SCFG *Cfg = builder.buildCFG(Walker);
753   LLVMPrinter::print(Cfg, llvm::errs());
754 }
755 
756 
757 
758 } // end namespace threadSafety
759 
760 } // end namespace clang
761