[PATCH] D37120: [analyzer] Fix modeling arithmetic

[Alexander Shaposhnikov via Phabricator via cfe-commits]

alexshap created this revision.
Herald added a subscriber: xazax.hun.

This diff attempts to fix modeling of arithmetic expressions
where pointers are treated as integers (i.e. via C-style / reinterpret casts).
In particular, it resolves https://bugs.llvm.org/show_bug.cgi?id=34309

Test plan: make check-all


Repository:
  rL LLVM

https://reviews.llvm.org/D37120

Files:
  lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp
  test/Analysis/ptr-arith.cpp


Index: test/Analysis/ptr-arith.cpp
===================================================================
--- test/Analysis/ptr-arith.cpp
+++ test/Analysis/ptr-arith.cpp
@@ -105,3 +105,9 @@
     return 0;
   return N;
 }
+
+// Bug 34309
+bool ptrAsIntegerSubtractionNoCrash(long x, char *p) {
+  long y = (long)p - 1;
+  return y == x;
+}
Index: lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp
===================================================================
--- lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp
+++ lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp
@@ -364,6 +364,13 @@
                              rhs.castAs<nonloc::LocAsInteger>().getLoc(),
                              resultTy);
         case nonloc::ConcreteIntKind: {
+          // Evaluate pointers treated as integers
+          // (for example, results of C-style casts (long)((void *)ptr))
+          // in arithmetic expressions with integers.
+          if (!BinaryOperator::isComparisonOp(op))
+            return makeSymExprValNN(
+                state, op, lhs.castAs<nonloc::LocAsInteger>(),
+                rhs.castAs<nonloc::ConcreteInt>(), resultTy);
           // Transform the integer into a location and compare.
           // FIXME: This only makes sense for comparisons. If we want to, say,
           // add 1 to a LocAsInteger, we'd better unpack the Loc and add to it,


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