[analyzer] Add support for escape of const pointers and use it to allow “newed” pointers to escape

Add a new callback that notifies checkers when a const pointer escapes. Currently, this only works
for const pointers passed as a top level parameter into a function. We need to differentiate the const
pointers escape from regular escape since the content pointed by const pointer will not change;
if it’s a file handle, a file cannot be closed; but delete is allowed on const pointers.

This should suppress several false positives reported by the NewDelete checker on llvm codebase.

llvm-svn: 178310

1 files changed, 14 insertions, 3 deletions

diff --git a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
index f245bbf49e1..8ad5a3dbdee 100644
--- a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
@@ -1714,11 +1714,12 @@ ProgramStateRef ExprEngine::processPointerEscapedOnBind(ProgramStateRef State,
 }
 
 ProgramStateRef 
-ExprEngine::processPointerEscapedOnInvalidateRegions(ProgramStateRef State,
+ExprEngine::notifyCheckersOfPointerEscape(ProgramStateRef State,
     const InvalidatedSymbols *Invalidated,
     ArrayRef<const MemRegion *> ExplicitRegions,
     ArrayRef<const MemRegion *> Regions,
-    const CallEvent *Call) {
+    const CallEvent *Call,
+    bool IsConst) {
   
   if (!Invalidated || Invalidated->empty())
     return State;
@@ -1728,7 +1729,17 @@ ExprEngine::processPointerEscapedOnInvalidateRegions(ProgramStateRef State,
                                                            *Invalidated,
                                                            0,
                                                            PSK_EscapeOther);
-    
+
+  // Note: Due to current limitations of RegionStore, we only process the top
+  // level const pointers correctly. The lower level const pointers are
+  // currently treated as non-const.
+  if (IsConst)
+    return getCheckerManager().runCheckersForPointerEscape(State,
+                                                        *Invalidated,
+                                                        Call,
+                                                        PSK_DirectEscapeOnCall,
+                                                        true);
+
   // If the symbols were invalidated by a call, we want to find out which ones 
   // were invalidated directly due to being arguments to the call.
   InvalidatedSymbols SymbolsDirectlyInvalidated;