https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63459
--- Comment #5 from Jan Hubicka <hubicka at ucw dot cz> ---
Hi,
does something like this make sense (I also updated the DECL_BY_REFERENCE
check.
We allow to put variable at address NULL with -fno-delete-null-pointer-checks
that IMO can let me to pass it by reference.
Why this is not part of tree_expr_nonzero_p and vrp is not simply calling
it to set up the value ranges?
Honza
Index: tree-vrp.c
===================================================================
--- tree-vrp.c (revision 215901)
+++ tree-vrp.c (working copy)
@@ -365,6 +365,18 @@ nonnull_arg_p (const_tree arg)
if (arg == cfun->static_chain_decl)
return true;
+ /* THIS argument of method is always non-NULL. */
+ if (TREE_CODE (TREE_TYPE (current_function_decl)) == METHOD_TYPE
+ && arg == DECL_ARGUMENTS (current_function_decl))
+ return true;
+
+ /* Parameters passed by invisible reference are also always non-NULL
+ unsless we explicitly allow symbol to have NULL address, that is
+ permitted by -fno-delete-null-pointer-checks. */
+ if (DECL_BY_REFERENCE (arg)
+ && flag_delete_null_pointer_checks)
+ return true;
+
fntype = TREE_TYPE (current_function_decl);
for (attrs = TYPE_ATTRIBUTES (fntype); attrs; attrs = TREE_CHAIN (attrs))
{
@@ -772,7 +784,8 @@ get_value_range (const_tree var)
set_value_range_to_varying (vr);
}
else if (TREE_CODE (sym) == RESULT_DECL
- && DECL_BY_REFERENCE (sym))
+ && DECL_BY_REFERENCE (sym)
+ && flag_delete_null_pointer_checks)
set_value_range_to_nonnull (vr, TREE_TYPE (sym));
}
