https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92412
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2019-11-07
Assignee|unassigned at gcc dot gnu.org |msebor at gcc dot
gnu.org
Ever confirmed|0 |1
--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
The otherwise untested change below allows the test case to be optimized as I
expect:
index fee4cc271cd..2af88f4dff3 100644
--- a/gcc/targhooks.c
+++ b/gcc/targhooks.c
@@ -1415,9 +1415,12 @@ default_ref_may_alias_errno (ao_ref *ref)
if (TYPE_UNSIGNED (TREE_TYPE (base))
|| TYPE_MODE (TREE_TYPE (base)) != TYPE_MODE (integer_type_node))
return false;
- /* The default implementation assumes an errno location
- declaration is never defined in the current compilation unit. */
+ /* The default implementation assumes an errno location declaration
+ is never defined in the current compilation unit and be aliased
+ by a local or read-only variable. */
if (DECL_P (base)
+ && DECL_EXTERNAL (base)
+ && !TREE_READONLY (base)
&& !TREE_STATIC (base))
return true;
else if (TREE_CODE (base) == MEM_REF
