https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61969
--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Andi Kleen from comment #6)
> I looked at this a bit more. It's definitely the nrv pass that causes the
> problem.
>
> When I disable it in the source code the 32bit version compiles correctly.
> I also tried disabling the next pass (cfgcleanup), but that didn't make a
> difference.
>
> It converts the local variable to be a value-expr.
>
> It's still not exactly clear who deletes the variable declaration though.
>
> There are two possibilities:
> - nrv shouldn't convert the variable in the first place
> - someone who messes with the variables forgets to check for value-exprs.
>
> ;; Function func_52 (func_52, funcdef_no=86, decl_uid=2858, cgraph_uid=54,
> symbol_order=1152)
>
> NRV Replaced: l_55 with: <retval>
> func_52 (uint32_t p_53)
> {
> extern const struct S0 l_55 = {.f0=4, .f1=40290, .f2=10, .f3=4}
> [value-expr: <retval>];
only automatic vars may have a VALUE_EXPR, certainly not 'extern const' stuff.
What does func_52 look like before the NRV pass? It must be sth like
<retval> = l_55;
?
Looks like a bug in nrv to me:
/* The returned value must be a local automatic variable of the
same type and alignment as the function's result. */
if (TREE_CODE (found) != VAR_DECL
|| TREE_THIS_VOLATILE (found)
|| DECL_CONTEXT (found) != current_function_decl
|| TREE_STATIC (found)
|| TREE_ADDRESSABLE (found)
|| DECL_ALIGN (found) > DECL_ALIGN (result)
|| !useless_type_conversion_p (result_type,
TREE_TYPE (found)))
return 0;
should probably use auto_var_in_fn_p which checks for !DECL_EXTERNAL as well.
Index: gcc/tree-nrv.c
===================================================================
--- gcc/tree-nrv.c (revision 215917)
+++ gcc/tree-nrv.c (working copy)
@@ -216,8 +216,7 @@ pass_nrv::execute (function *fun)
same type and alignment as the function's result. */
if (TREE_CODE (found) != VAR_DECL
|| TREE_THIS_VOLATILE (found)
- || DECL_CONTEXT (found) != current_function_decl
- || TREE_STATIC (found)
+ || !auto_var_in_fn_p (found, current_function_decl)
|| TREE_ADDRESSABLE (found)
|| DECL_ALIGN (found) > DECL_ALIGN (result)
|| !useless_type_conversion_p (result_type,
> <bb 2>:
> return <retval>;
>
> }
