[polly] r280938 - DependenceInfo: Make clear that no double-free problem exists

[Tobias Grosser via llvm-commits]

Author: grosser
Date: Thu Sep  8 09:08:01 2016
New Revision: 280938

URL: http://llvm.org/viewvc/llvm-project?rev=280938&view=rev
Log:
DependenceInfo: Make clear that no double-free problem exists

When running the clang static analyser to check for memory issues, this code
originally showed a double free, as the analyser was unable to understand that
isl_union_map_free always returns NULL and consequently later uses of the isl
object we just freed will never be reached. Without this knowledge, the analyser
has to issue a warning.

We refactor the code to make it clear that for empty maps the current loop
iteration is aborted.

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

Modified: polly/trunk/lib/Analysis/DependenceInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Analysis/DependenceInfo.cpp?rev=280938&r1=280937&r2=280938&view=diff
==============================================================================
--- polly/trunk/lib/Analysis/DependenceInfo.cpp (original)
+++ polly/trunk/lib/Analysis/DependenceInfo.cpp Thu Sep  8 09:08:01 2016
@@ -537,8 +537,10 @@ void Dependences::calculateDependences(S
       isl_set *AccDomW = isl_map_wrap(MA->getAccessRelation());
       isl_union_map *AccRedDepU = isl_union_map_intersect_domain(
           isl_union_map_copy(TC_RED), isl_union_set_from_set(AccDomW));
-      if (isl_union_map_is_empty(AccRedDepU) && !isl_union_map_free(AccRedDepU))
+      if (isl_union_map_is_empty(AccRedDepU)) {
+        isl_union_map_free(AccRedDepU);
         continue;
+      }
 
       isl_map *AccRedDep = isl_map_from_union_map(AccRedDepU);
       RED_SIN = isl_union_map_add_map(RED_SIN, isl_map_copy(AccRedDep));