[gcc r13-3468] analyzer: handle (NULL == &VAR) [PR107345]

[gcc r13-3468] analyzer: handle (NULL == &VAR) [PR107345]

[David Malcolm]

https://gcc.gnu.org/g:18faaeb3af42f3d7dc609b9b91df77d0d59b16f6

commit r13-3468-g18faaeb3af42f3d7dc609b9b91df77d0d59b16f6
Author: David Malcolm <dmalcolm@redhat.com>
Date:   Mon Oct 24 16:38:23 2022 -0400

    analyzer: handle (NULL == &VAR) [PR107345]
    
    gcc/analyzer/ChangeLog:
            PR analyzer/107345
            * region-model.cc (region_model::eval_condition_without_cm):
            Ensure that constants are on the right-hand side before checking
            for them.
    
    gcc/testsuite/ChangeLog:
            PR analyzer/107345
            * gcc.dg/analyzer/pr107345.c: New test.
    
    Signed-off-by: David Malcolm <dmalcolm@redhat.com>

Diff:
---
 gcc/analyzer/region-model.cc             | 15 ++++++++++++---
 gcc/testsuite/gcc.dg/analyzer/pr107345.c | 17 +++++++++++++++++
 2 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/gcc/analyzer/region-model.cc b/gcc/analyzer/region-model.cc
index 608fcd58fab..7c44fc9e253 100644
--- a/gcc/analyzer/region-model.cc
+++ b/gcc/analyzer/region-model.cc
@@ -4212,10 +4212,19 @@ region_model::eval_condition_without_cm (const svalue *lhs,
 	/* Otherwise, only known through constraints.  */
       }
 
-  /* If we have a pair of constants, compare them.  */
   if (const constant_svalue *cst_lhs = lhs->dyn_cast_constant_svalue ())
-    if (const constant_svalue *cst_rhs = rhs->dyn_cast_constant_svalue ())
-      return constant_svalue::eval_condition (cst_lhs, op, cst_rhs);
+    {
+      /* If we have a pair of constants, compare them.  */
+      if (const constant_svalue *cst_rhs = rhs->dyn_cast_constant_svalue ())
+	return constant_svalue::eval_condition (cst_lhs, op, cst_rhs);
+      else
+	{
+	  /* When we have one constant, put it on the RHS.  */
+	  std::swap (lhs, rhs);
+	  op = swap_tree_comparison (op);
+	}
+    }
+  gcc_assert (lhs->get_kind () != SK_CONSTANT);
 
   /* Handle comparison against zero.  */
   if (const constant_svalue *cst_rhs = rhs->dyn_cast_constant_svalue ())
diff --git a/gcc/testsuite/gcc.dg/analyzer/pr107345.c b/gcc/testsuite/gcc.dg/analyzer/pr107345.c
new file mode 100644
index 00000000000..540596d1182
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/pr107345.c
@@ -0,0 +1,17 @@
+/* Ensure the analyzer treats (NULL == &e) as being false for this case,
+   where the logic is sufficiently complicated to not be optimized away.  */
+
+#include <stdio.h>
+
+int main() {   
+  int e = 10086;
+  int *f = &e;
+  int g = 0;
+  int *h[2][1];
+  h[1][0] = f;
+  if (g == (h[1][0])) { /* { dg-warning "comparison between pointer and integer" } */
+    unsigned int *i = 0;
+  }
+  printf("NPD_FLAG: %d\n ", *f);
+  return 0;
+}