diff options
Diffstat (limited to 'gcc/tree-vrp.c')
| -rw-r--r-- | gcc/tree-vrp.c | 23 |
1 files changed, 20 insertions, 3 deletions
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c index 6fd1fd2..15ac65b 100644 --- a/gcc/tree-vrp.c +++ b/gcc/tree-vrp.c @@ -1673,9 +1673,26 @@ extract_range_from_binary_expr (value_range_base *vr, else if (code == POINTER_PLUS_EXPR) { /* For pointer types, we are really only interested in asserting - whether the expression evaluates to non-NULL. */ - if (!range_includes_zero_p (&vr0) - || !range_includes_zero_p (&vr1)) + whether the expression evaluates to non-NULL. + With -fno-delete-null-pointer-checks we need to be more + conservative. As some object might reside at address 0, + then some offset could be added to it and the same offset + subtracted again and the result would be NULL. + E.g. + static int a[12]; where &a[0] is NULL and + ptr = &a[6]; + ptr -= 6; + ptr will be NULL here, even when there is POINTER_PLUS_EXPR + where the first range doesn't include zero and the second one + doesn't either. As the second operand is sizetype (unsigned), + consider all ranges where the MSB could be set as possible + subtractions where the result might be NULL. */ + if ((!range_includes_zero_p (&vr0) + || !range_includes_zero_p (&vr1)) + && !TYPE_OVERFLOW_WRAPS (expr_type) + && (flag_delete_null_pointer_checks + || (range_int_cst_p (&vr1) + && !tree_int_cst_sign_bit (vr1.max ())))) vr->set_nonnull (expr_type); else if (range_is_null (&vr0) && range_is_null (&vr1)) vr->set_null (expr_type); |