ranger: Improve nonnull_if_nonzero attribute [PR117023]

On Mon, Mar 31, 2025 at 11:30:20AM -0400, Andrew MacLeod wrote:
> Infer range processing was adjusted to allow a query to be specified,
> but during VRP folding, ranger w3as not providing a query.  This results
> in contextual ranges being missed.   Pass the cache in as the query
> which provide a read-only query of the current state.

Now that this patch is in, I've retested my patch and it works fine.
If we can determine a range for the arg2 argument and prove that it
doesn't include zero, we can imply nonzero for the arg1 argument.

2025-05-02  Jakub Jelinek  <jakub@redhat.com>
	    Andrew MacLeod  <amacleod@redhat.com>

	PR c/117023
	* gimple-range-infer.cc (gimple_infer_range::gimple_infer_range):
	For nonnull_if_nonzero attribute check also arg2 range if it doesn't
	include zero and in that case call add_nonzero too.

	* gcc.dg/tree-ssa/pr78154-2.c: New test.

diff --git a/gcc/gimple-range-infer.cc b/gcc/gimple-range-infer.cc
index 3b1abbef566374f186c55e0babaf19d5ca6f3f9f..72f71b980598c60cdd39094a309d2ce9905c0e88 100644 (file)
--- a/gcc/gimple-range-infer.cc
+++ b/gcc/gimple-range-infer.cc
@@ -208,8 +208,13 @@ gimple_infer_range::gimple_infer_range (gimple *s, range_query *q,
                  continue;
                if (integer_nonzerop (arg2))
                  add_nonzero (arg);
-               // FIXME: Can one query here whether arg2 has
-               // nonzero range if it is a SSA_NAME?
+               else
+                 {
+                   value_range r (TREE_TYPE (arg2));
+                   if (q->range_of_expr (r, arg2, s)
+                       && !r.contains_p (build_zero_cst (TREE_TYPE (arg2))))
+                     add_nonzero (arg);
+                 }
              }
          }
       // Fallthru and walk load/store ops now.

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr78154-2.c b/gcc/testsuite/gcc.dg/tree-ssa/pr78154-2.c
new file mode 100644 (file)
index 0000000..3b2cbd8
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr78154-2.c
@@ -0,0 +1,38 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-evrp-slim -fdelete-null-pointer-checks" } */
+/* { dg-skip-if "" { keeps_null_pointer_checks } } */
+
+void foo (void *, __SIZE_TYPE__) __attribute__((nonnull_if_nonzero (1, 2)));
+void baz (void);
+
+void
+bar (void *a, void *b, void *c, void *d, void *e, __SIZE_TYPE__ n)
+{
+  foo (a, 42);
+  if (a == 0)
+    __builtin_abort ();
+  if (n)
+    {
+      foo (b, n);
+      if (b == 0)
+       __builtin_abort ();
+    }
+  if (n >= 42)
+    {
+      foo (c, n - 10);
+      if (c == 0)
+       __builtin_abort ();
+    }
+  foo (d, 0);
+  if (d == 0)
+    baz ();
+  if (n != 42)
+    {
+      foo (e, n);
+      if (e == 0)
+       baz ();
+    }
+}
+
+/* { dg-final { scan-tree-dump-not "__builtin_abort" "evrp" } } */
+/* { dg-final { scan-tree-dump-times "baz \\\(" 2 "evrp" } } */