diff options
Diffstat (limited to 'gcc/alias.c')
| -rw-r--r-- | gcc/alias.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/gcc/alias.c b/gcc/alias.c index 1e4c4d1..dd1dfd3 100644 --- a/gcc/alias.c +++ b/gcc/alias.c @@ -619,6 +619,14 @@ component_uses_parent_alias_set_from (const_tree t) case COMPONENT_REF: if (DECL_NONADDRESSABLE_P (TREE_OPERAND (t, 1))) found = t; + /* Permit type-punning when accessing a union, provided the access + is directly through the union. For example, this code does not + permit taking the address of a union member and then storing + through it. Even the type-punning allowed here is a GCC + extension, albeit a common and useful one; the C standard says + that such accesses have implementation-defined behavior. */ + else if (TREE_CODE (TREE_TYPE (TREE_OPERAND (t, 0))) == UNION_TYPE) + found = t; break; case ARRAY_REF: |