r347955 - [analyzer] MallocChecker: Avoid redundant transitions.

[Artem Dergachev via cfe-commits]

Author: dergachev
Date: Thu Nov 29 19:52:42 2018
New Revision: 347955

URL: http://llvm.org/viewvc/llvm-project?rev=347955&view=rev
Log:
[analyzer] MallocChecker: Avoid redundant transitions.

Don't generate a checker-tagged node unconditionally on the first
checkDeadSymbols callback when no pointers are tracked.

This is a tiny performance optimization; it may change the behavior slightly
by making Static Analyzer bail out on max-nodes one node later (which is good)
but any test would either break for no good reason or become useless
every time someone sneezes.

Differential Revision: https://reviews.llvm.org/D54013

Modified:
    cfe/trunk/lib/StaticAnalyzer/Checkers/MallocChecker.cpp

Modified: cfe/trunk/lib/StaticAnalyzer/Checkers/MallocChecker.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/StaticAnalyzer/Checkers/MallocChecker.cpp?rev=347955&r1=347954&r2=347955&view=diff
==============================================================================
--- cfe/trunk/lib/StaticAnalyzer/Checkers/MallocChecker.cpp (original)
+++ cfe/trunk/lib/StaticAnalyzer/Checkers/MallocChecker.cpp Thu Nov 29 19:52:42 2018
@@ -2346,9 +2346,10 @@ void MallocChecker::checkDeadSymbols(Sym
                                      CheckerContext &C) const
 {
   ProgramStateRef state = C.getState();
-  RegionStateTy RS = state->get<RegionState>();
+  RegionStateTy OldRS = state->get<RegionState>();
   RegionStateTy::Factory &F = state->get_context<RegionState>();
 
+  RegionStateTy RS = OldRS;
   SmallVector<SymbolRef, 2> Errors;
   for (RegionStateTy::iterator I = RS.begin(), E = RS.end(); I != E; ++I) {
     if (SymReaper.isDead(I->first)) {
@@ -2356,10 +2357,18 @@ void MallocChecker::checkDeadSymbols(Sym
         Errors.push_back(I->first);
       // Remove the dead symbol from the map.
       RS = F.remove(RS, I->first);
-
     }
   }
 
+  if (RS == OldRS) {
+    // We shouldn't have touched other maps yet.
+    assert(state->get<ReallocPairs>() ==
+           C.getState()->get<ReallocPairs>());
+    assert(state->get<FreeReturnValue>() ==
+           C.getState()->get<FreeReturnValue>());
+    return;
+  }
+
   // Cleanup the Realloc Pairs Map.
   ReallocPairsTy RP = state->get<ReallocPairs>();
   for (ReallocPairsTy::iterator I = RP.begin(), E = RP.end(); I != E; ++I) {