[analyzer] Run remove dead bindings right before leaving a function.

This is needed to ensure that we always report issues in the correct
function. For example, leaks are identified when we call remove dead
bindings. In order to make sure we report a callee's leak in the callee,
we have to run the operation in the callee's context.

This change required quite a bit of infrastructure work since:
 - We used to only run remove dead bindings before a given statement;
here we need to run it after the last statement in the function. For
this, we added additional Program Point and special mode in the
SymbolReaper to remove all symbols in context lower than the current
one.
 - The call exit operation turned into a sequence of nodes, which are
now guarded by CallExitBegin and CallExitEnd nodes for clarity and
convenience.

(Sorry for the long diff.)

llvm-svn: 155244

1 files changed, 11 insertions, 6 deletions

diff --git a/clang/lib/StaticAnalyzer/Core/CheckerManager.cpp b/clang/lib/StaticAnalyzer/Core/CheckerManager.cpp
index 0bcc343fba8..8a6ea1d0f80 100644
--- a/clang/lib/StaticAnalyzer/Core/CheckerManager.cpp
+++ b/clang/lib/StaticAnalyzer/Core/CheckerManager.cpp
@@ -381,21 +381,25 @@ namespace {
     SymbolReaper &SR;
     const Stmt *S;
     ExprEngine &Eng;
+    ProgramPoint::Kind ProgarmPointKind;
 
     CheckersTy::const_iterator checkers_begin() { return Checkers.begin(); }
     CheckersTy::const_iterator checkers_end() { return Checkers.end(); }
 
     CheckDeadSymbolsContext(const CheckersTy &checkers, SymbolReaper &sr,
-                            const Stmt *s, ExprEngine &eng)
-      : Checkers(checkers), SR(sr), S(s), Eng(eng) { }
+                            const Stmt *s, ExprEngine &eng,
+                            ProgramPoint::Kind K)
+      : Checkers(checkers), SR(sr), S(s), Eng(eng), ProgarmPointKind(K) { }
 
     void runChecker(CheckerManager::CheckDeadSymbolsFunc checkFn,
                     NodeBuilder &Bldr, ExplodedNode *Pred) {
-      ProgramPoint::Kind K = ProgramPoint::PostPurgeDeadSymbolsKind;
-      const ProgramPoint &L = ProgramPoint::getProgramPoint(S, K,
+      const ProgramPoint &L = ProgramPoint::getProgramPoint(S, ProgarmPointKind,
                                 Pred->getLocationContext(), checkFn.Checker);
       CheckerContext C(Bldr, Eng, Pred, L);
 
+      // Note, do not pass the statement to the checkers without letting them
+      // differentiate if we ran remove dead bindings before or after the
+      // statement.
       checkFn(SR, C);
     }
   };
@@ -406,8 +410,9 @@ void CheckerManager::runCheckersForDeadSymbols(ExplodedNodeSet &Dst,
                                                const ExplodedNodeSet &Src,
                                                SymbolReaper &SymReaper,
                                                const Stmt *S,
-                                               ExprEngine &Eng) {
-  CheckDeadSymbolsContext C(DeadSymbolsCheckers, SymReaper, S, Eng);
+                                               ExprEngine &Eng,
+                                               ProgramPoint::Kind K) {
+  CheckDeadSymbolsContext C(DeadSymbolsCheckers, SymReaper, S, Eng, K);
   expandGraphWithCheckers(C, Dst, Src);
 }