> Hi,
> this patch drops test for TYPE_NEEDS_CONSTRUCTING in tree.h and instead
> sets TREE_READONLY to 0 for external vars of this type. For vars
> declared locally we drop TREE_READONLY while expanding constructor.
> Note that I have tried to drop TREE_READONLY always (not only for
> DECL_EXTERNAL) and it breaks a testcase where constructor is constexpr.
> So perhaps this is unnecesarily conservative for external vars having
> constexpr cotr and perhaps it is better done by frontend.
>
> Curiously enough, this does not fix the actual testcase in PR88677.
This turned out to be bug in my patch: I cleared the flag too late so
free_lang_data caused very much same effect as the may_be_aliased flag.
Here is updated patch, bootstrapped/regtested x86_64-linux. It also
fixes the testcase though I am not quite sure how to add it to
testsuite.
>
> Bootstrapped/regtested x86_64-linux, makes sense?
>
PR lto/88777
* cgraphunit.c (analyze_functions): Clear READONLY flag for external
types that needs constructiong.
* tree.h (may_be_aliased): Do not check TYPE_NEEDS_CONSTRUCTING.
Index: cgraphunit.c
===================================================================
--- cgraphunit.c (revision 268741)
+++ cgraphunit.c (working copy)
@@ -1226,6 +1226,15 @@ analyze_functions (bool first_time)
&& node != first_handled_var; node = next)
{
next = node->next;
+ /* For symbols declared locally we clear TREE_READONLY when emitting
+ the construtor (if one is needed). For external declarations we can
+ not safely assume that the type is readonly because we may be called
+ during its construction. */
+ if (TREE_CODE (node->decl) == VAR_DECL
+ && TYPE_P (TREE_TYPE (node->decl))
+ && TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (node->decl))
+ && DECL_EXTERNAL (node->decl))
+ TREE_READONLY (node->decl) = 0;
if (!node->aux && !node->referred_to_p ())
{
if (symtab->dump_file)
Index: tree.h
===================================================================
--- tree.h (revision 268741)
+++ tree.h (working copy)
@@ -5371,8 +5371,7 @@ may_be_aliased (const_tree var)
|| DECL_EXTERNAL (var)
|| TREE_ADDRESSABLE (var))
&& !((TREE_STATIC (var) || TREE_PUBLIC (var) || DECL_EXTERNAL (var))
- && ((TREE_READONLY (var)
- && !TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (var)))
+ && (TREE_READONLY (var)
|| (TREE_CODE (var) == VAR_DECL
&& DECL_NONALIASED (var)))));
}
