r338420 - [analyzer] Don't try to simplify mixed Loc/NonLoc expressions.

[Artem Dergachev via cfe-commits]

Author: dergachev
Date: Tue Jul 31 12:26:34 2018
New Revision: 338420

URL: http://llvm.org/viewvc/llvm-project?rev=338420&view=rev
Log:
[analyzer] Don't try to simplify mixed Loc/NonLoc expressions.

This fix is similar to r337769 and addresses a regression caused by r337167.

When an operation between a nonloc::LocAsInteger and a non-pointer symbol
is performed, the LocAsInteger-specific part of information is lost.
When the non-pointer symbol is collapsing into a constant, we cannot easily
re-evaluate the result, because we need to recover the missing
LocAsInteger-specific information (eg., integer type, or the very fact that
this pointer was at some point converted to an integer).

Add one more defensive check to prevent crashes on trying to simplify a
SymSymExpr with different Loc-ness of operands.

Differential Revision: 

Modified:
    cfe/trunk/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp
    cfe/trunk/test/Analysis/casts.c

Modified: cfe/trunk/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp?rev=338420&r1=338419&r2=338420&view=diff
==============================================================================
--- cfe/trunk/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp (original)
+++ cfe/trunk/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp Tue Jul 31 12:26:34 2018
@@ -1291,6 +1291,17 @@ SVal SimpleSValBuilder::simplifySVal(Pro
       if (I != Cached.end())
         return I->second;
 
+      // For now don't try to simplify mixed Loc/NonLoc expressions
+      // because they often appear from LocAsInteger operations
+      // and we don't know how to combine a LocAsInteger
+      // with a concrete value.
+      if (Loc::isLocType(S->getLHS()->getType()) !=
+          Loc::isLocType(S->getRHS()->getType())) {
+        SVal V = SVB.makeSymbolVal(S);
+        Cached[S] = V;
+        return V;
+      }
+
       SVal LHS = Visit(S->getLHS());
       SVal RHS = Visit(S->getRHS());
       if (isUnchanged(S->getLHS(), LHS) && isUnchanged(S->getRHS(), RHS)) {

Modified: cfe/trunk/test/Analysis/casts.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/casts.c?rev=338420&r1=338419&r2=338420&view=diff
==============================================================================
--- cfe/trunk/test/Analysis/casts.c (original)
+++ cfe/trunk/test/Analysis/casts.c Tue Jul 31 12:26:34 2018
@@ -175,3 +175,10 @@ void testCastVoidPtrToIntPtrThroughUIntT
 void testLocNonLocSymbolAssume(int a, int *b) {
   if ((int)b < a) {} // no-crash
 }
+
+void testLocNonLocSymbolRemainder(int a, int *b) {
+  int c = ((int)b) % a;
+  if (a == 1) {
+    c += 1;
+  }
+}