[analyzer] Overhaul how the static analyzer expects CFGs by forcing CFGs to be linearized only when used by the static analyzer. This required a rewrite of LiveVariables, and exposed a ton of subtle bugs.

The motivation of this large change is to drastically simplify the logic in ExprEngine going forward.

Some fallout is that the output of some BugReporterVisitors is not as accurate as before; those will
need to be fixed over time.  There is also some possible performance regression as RemoveDeadBindings
will be called frequently; this can also be improved over time.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@136419 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 30 insertions, 32 deletions

diff --git a/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp b/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp
index 2c5a1a255d..f86bf55c32 100644
--- a/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp
+++ b/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp
@@ -68,12 +68,12 @@ void ReachableCode::computeReachableBlocks() {
 }
 
 namespace {
-class DeadStoreObs : public LiveVariables::ObserverTy {
+class DeadStoreObs : public LiveVariables::Observer {
   const CFG &cfg;
   ASTContext &Ctx;
   BugReporter& BR;
   ParentMap& Parents;
-  llvm::SmallPtrSet<VarDecl*, 20> Escaped;
+  llvm::SmallPtrSet<const VarDecl*, 20> Escaped;
   llvm::OwningPtr<ReachableCode> reachableCode;
   const CFGBlock *currentBlock;
 
@@ -82,13 +82,14 @@ class DeadStoreObs : public LiveVariables::ObserverTy {
 public:
   DeadStoreObs(const CFG &cfg, ASTContext &ctx,
                BugReporter& br, ParentMap& parents,
-               llvm::SmallPtrSet<VarDecl*, 20> &escaped)
+               llvm::SmallPtrSet<const VarDecl*, 20> &escaped)
     : cfg(cfg), Ctx(ctx), BR(br), Parents(parents),
       Escaped(escaped), currentBlock(0) {}
 
   virtual ~DeadStoreObs() {}
 
-  void Report(VarDecl* V, DeadStoreKind dsk, SourceLocation L, SourceRange R) {
+  void Report(const VarDecl* V, DeadStoreKind dsk,
+              SourceLocation L, SourceRange R) {
     if (Escaped.count(V))
       return;
     
@@ -134,10 +135,9 @@ public:
     BR.EmitBasicReport(BugType, "Dead store", msg, L, R);
   }
 
-  void CheckVarDecl(VarDecl* VD, Expr* Ex, Expr* Val,
+  void CheckVarDecl(const VarDecl* VD, const Expr* Ex, const Expr* Val,
                     DeadStoreKind dsk,
-                    const LiveVariables::AnalysisDataTy& AD,
-                    const LiveVariables::ValTy& Live) {
+                    const LiveVariables::LivenessValues &Live) {
 
     if (!VD->hasLocalStorage())
       return;
@@ -146,30 +146,29 @@ public:
     if (VD->getType()->getAs<ReferenceType>())
       return;
 
-    if (!Live(VD, AD) && 
+    if (!Live.isLive(VD) && 
         !(VD->getAttr<UnusedAttr>() || VD->getAttr<BlocksAttr>()))
       Report(VD, dsk, Ex->getSourceRange().getBegin(),
              Val->getSourceRange());
   }
 
-  void CheckDeclRef(DeclRefExpr* DR, Expr* Val, DeadStoreKind dsk,
-                    const LiveVariables::AnalysisDataTy& AD,
-                    const LiveVariables::ValTy& Live) {
-    if (VarDecl* VD = dyn_cast<VarDecl>(DR->getDecl()))
-      CheckVarDecl(VD, DR, Val, dsk, AD, Live);
+  void CheckDeclRef(const DeclRefExpr* DR, const Expr* Val, DeadStoreKind dsk,
+                    const LiveVariables::LivenessValues& Live) {
+    if (const VarDecl* VD = dyn_cast<VarDecl>(DR->getDecl()))
+      CheckVarDecl(VD, DR, Val, dsk, Live);
   }
 
-  bool isIncrement(VarDecl* VD, BinaryOperator* B) {
+  bool isIncrement(VarDecl* VD, const BinaryOperator* B) {
     if (B->isCompoundAssignmentOp())
       return true;
 
-    Expr* RHS = B->getRHS()->IgnoreParenCasts();
-    BinaryOperator* BRHS = dyn_cast<BinaryOperator>(RHS);
+    const Expr* RHS = B->getRHS()->IgnoreParenCasts();
+    const BinaryOperator* BRHS = dyn_cast<BinaryOperator>(RHS);
 
     if (!BRHS)
       return false;
 
-    DeclRefExpr *DR;
+    const DeclRefExpr *DR;
 
     if ((DR = dyn_cast<DeclRefExpr>(BRHS->getLHS()->IgnoreParenCasts())))
       if (DR->getDecl() == VD)
@@ -182,9 +181,8 @@ public:
     return false;
   }
 
-  virtual void ObserveStmt(Stmt* S, const CFGBlock *block,
-                           const LiveVariables::AnalysisDataTy& AD,
-                           const LiveVariables::ValTy& Live) {
+  virtual void observeStmt(const Stmt* S, const CFGBlock *block,
+                           const LiveVariables::LivenessValues &Live) {
 
     currentBlock = block;
     
@@ -194,7 +192,7 @@ public:
 
     // Only cover dead stores from regular assignments.  ++/-- dead stores
     // have never flagged a real bug.
-    if (BinaryOperator* B = dyn_cast<BinaryOperator>(S)) {
+    if (const BinaryOperator* B = dyn_cast<BinaryOperator>(S)) {
       if (!B->isAssignmentOp()) return; // Skip non-assignments.
 
       if (DeclRefExpr* DR = dyn_cast<DeclRefExpr>(B->getLHS()))
@@ -220,26 +218,26 @@ public:
                               ? Enclosing
                               : (isIncrement(VD,B) ? DeadIncrement : Standard);
 
-          CheckVarDecl(VD, DR, B->getRHS(), dsk, AD, Live);
+          CheckVarDecl(VD, DR, B->getRHS(), dsk, Live);
         }
     }
-    else if (UnaryOperator* U = dyn_cast<UnaryOperator>(S)) {
+    else if (const UnaryOperator* U = dyn_cast<UnaryOperator>(S)) {
       if (!U->isIncrementOp() || U->isPrefix())
         return;
 
-      Stmt *parent = Parents.getParentIgnoreParenCasts(U);
+      const Stmt *parent = Parents.getParentIgnoreParenCasts(U);
       if (!parent || !isa<ReturnStmt>(parent))
         return;
 
-      Expr *Ex = U->getSubExpr()->IgnoreParenCasts();
+      const Expr *Ex = U->getSubExpr()->IgnoreParenCasts();
 
-      if (DeclRefExpr* DR = dyn_cast<DeclRefExpr>(Ex))
-        CheckDeclRef(DR, U, DeadIncrement, AD, Live);
+      if (const DeclRefExpr* DR = dyn_cast<DeclRefExpr>(Ex))
+        CheckDeclRef(DR, U, DeadIncrement, Live);
     }
-    else if (DeclStmt* DS = dyn_cast<DeclStmt>(S))
+    else if (const DeclStmt* DS = dyn_cast<DeclStmt>(S))
       // Iterate through the decls.  Warn if any initializers are complex
       // expressions that are not live (never used).
-      for (DeclStmt::decl_iterator DI=DS->decl_begin(), DE=DS->decl_end();
+      for (DeclStmt::const_decl_iterator DI=DS->decl_begin(), DE=DS->decl_end();
            DI != DE; ++DI) {
 
         VarDecl* V = dyn_cast<VarDecl>(*DI);
@@ -265,7 +263,7 @@ public:
             // A dead initialization is a variable that is dead after it
             // is initialized.  We don't flag warnings for those variables
             // marked 'unused'.
-            if (!Live(V, AD) && V->getAttr<UnusedAttr>() == 0) {
+            if (!Live.isLive(V) && V->getAttr<UnusedAttr>() == 0) {
               // Special case: check for initializations with constants.
               //
               //  e.g. : int x = 0;
@@ -318,7 +316,7 @@ public:
 
   CFG& getCFG() { return *cfg; }
 
-  llvm::SmallPtrSet<VarDecl*, 20> Escaped;
+  llvm::SmallPtrSet<const VarDecl*, 20> Escaped;
 
   void VisitUnaryOperator(UnaryOperator* U) {
     // Check for '&'.  Any VarDecl whose value has its address-taken we
@@ -351,7 +349,7 @@ public:
       FindEscaped FS(&cfg);
       FS.getCFG().VisitBlockStmts(FS);
       DeadStoreObs A(cfg, BR.getContext(), BR, pmap, FS.Escaped);
-      L->runOnAllBlocks(cfg, &A);
+      L->runOnAllBlocks(A);
     }
   }
 };