[analyzer] Fixit for r158136.

I falsely assumed that the memory spaces are equal when we reach this
point, they might not be when memory space of one or more is stack or
Unknown. We don't want a region from Heap space alias something with
another memory space.

llvm-svn: 158165

clang/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp

@@ -701,7 +701,7 @@ SVal SimpleSValBuilder::evalBinOpLL(ProgramStateRef state,
     // on each invocation.
     if (LeftBase != RightBase &&
         ((!isa<SymbolicRegion>(LeftBase) && !isa<SymbolicRegion>(RightBase)) ||
-         isa<HeapSpaceRegion>(LeftMS)) ){
+         (isa<HeapSpaceRegion>(LeftMS) || isa<HeapSpaceRegion>(RightMS))) ){
       switch (op) {
       default:
         return UnknownVal();

clang/test/Analysis/malloc.c

@@ -902,6 +902,23 @@ int HeapAssignment() {
   return 0;
 }
 
+int *retPtr();
+int *retPtrMightAlias(int *x);
+int cmpHeapAllocationToUnknown() {
+  int zero = 0;
+  int *yBefore = retPtr();
+  int *m = malloc(8);
+  int *yAfter = retPtrMightAlias(m);
+  if (yBefore == m) {
+    return 5/zero; // expected-warning {{This statement is never executed}}
+  }
+  if (yAfter == m) {
+    return 5/zero; // expected-warning {{This statement is never executed}}
+  }
+  free(m);
+  return 0;
+}
+
 // ----------------------------------------------------------------------------
 // False negatives.