On Wed, Mar 17, 2010 at 5:32 PM, Jakub Jelinek <ja...@redhat.com> wrote:
> On Wed, Mar 17, 2010 at 12:06:49PM -0400, Aldy Hernandez wrote:
>> What happens is that rtl_for_decl_location():dwarf2out.c will call
>> make_decl_rtl() which further down the call chain will call
>> get_alias_set/new_alias_set. It matters not that we reset DECL_RTL
>> immediately after, we have already created a new alias set for first
>> time callers:
>>
>> /* Try harder to get a rtl. If this symbol ends up not being emitted
>> in the current CU, resolve_addr will remove the expression referencing
>> it. */
>> ...
>> ...
>> {
>> rtl = DECL_RTL (decl);
>> /* Reset DECL_RTL back, as various parts of the compiler expects
>> DECL_RTL set meaning it is actually going to be output. */
>> SET_DECL_RTL (decl, NULL);
>
> expand_debug_expr is another such spot.
> I guess best would be to make sure no new alias set is created in these
> places. Perhaps
> int save_strict_aliasing = flag_strict_aliasing;
> flag_strict_aliasing = 0;
> rtl = DECL_RTL (decl);
> flag_strict_aliasing = save_strict_aliasing;
> in both places?
> The rtls created this way are used only for DEBUG purposes.
> I bet C/C++ FEs create the alias set for the decls much earlier...
Ugh. I'd rather simply drop alias-sets from compare-debug dumps.
But ..
rtl = DECL_RTL (decl);
/* Reset DECL_RTL back, as various parts of the compiler expects
DECL_RTL set meaning it is actually going to be output. */
SET_DECL_RTL (decl, NULL);
... why do this in the first place? Is this an issue for all decls or just
for DEBUG_DECLs? For DEBUG_DECLs you could refuse to assign
alias-sets in get_alias_set by returning 0 for them.
Richard.
> Jakub
>
