[polly] r262235 - [ScopDetection] Fix use-after-free.

[Michael Kruse via llvm-commits]

Author: meinersbur
Date: Mon Feb 29 10:54:18 2016
New Revision: 262235

URL: http://llvm.org/viewvc/llvm-project?rev=262235&view=rev
Log:
[ScopDetection] Fix use-after-free.

removeCachedResults deletes the DetectionContext from
DetectionContextMap such that any it cannot be used anymore.
Unfortunately invalid<ReportUnprofitable> and RejectLogs.insert still do
use it. Because the memory is part of a map and not returned to to the
OS immediatly, such that the observable effect was only a memory leak
due to reference counters not decreased when the second call to
removeCachedResults does not remove the DetectionContext because because
it already has been removed.

Fix by not removing the DetectionContext prematurely. The second call to
removeCachedResults will handle it anyway.

Modified:
    polly/trunk/lib/Analysis/ScopDetection.cpp

Modified: polly/trunk/lib/Analysis/ScopDetection.cpp
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Analysis/ScopDetection.cpp?rev=262235&r1=262234&r2=262235&view=diff
==============================================================================
--- polly/trunk/lib/Analysis/ScopDetection.cpp (original)
+++ polly/trunk/lib/Analysis/ScopDetection.cpp Mon Feb 29 10:54:18 2016
@@ -1150,10 +1150,9 @@ void ScopDetection::findScops(Region &R)
   DetectionContext &Context = It.first->second;
 
   bool RegionIsValid = false;
-  if (!PollyProcessUnprofitable && regionWithoutLoops(R, LI)) {
-    removeCachedResults(R);
+  if (!PollyProcessUnprofitable && regionWithoutLoops(R, LI))
     invalid<ReportUnprofitable>(Context, /*Assert=*/true, &R);
-  } else
+  else
     RegionIsValid = isValidRegion(Context);
 
   bool HasErrors = !RegionIsValid || Context.Log.size() > 0;