Re: [PATCH] c++: Optimize in maybe_clone_body aliases even when not at_eof [PR113208]

[Jason Merrill <jason@redhat.com>]

On 5/9/24 14:20, Jakub Jelinek wrote:
> On Thu, Apr 25, 2024 at 11:30:48AM -0400, Jason Merrill wrote:
>> Hmm, maybe maybe_clone_body shouldn't clear DECL_SAVED_TREE for aliases, but
>> rather set it to some stub like void_node?
>>
>> Though with all these changes, it's probably better to go with your first
>> patch for GCC 14 and delay this approach to 15.  Your v1 patch is OK for 14.
> 
> Ok, here is an updated patch, which sets DECL_SAVED_TREE to void_node for
> the aliases together with reversion of the earlier committed patch.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
> 
> 2024-05-09  Jakub Jelinek  <jakub@redhat.com>
> 	    Jason Merrill  <jason@redhat.com>
> 
> 	PR lto/113208
> 	* cp-tree.h (maybe_optimize_cdtor): Remove.
> 	* decl2.cc (tentative_decl_linkage): Call maybe_make_one_only
> 	for implicit instantiations of maybe in charge ctors/dtors
> 	declared inline.
> 	(import_export_decl): Don't call maybe_optimize_cdtor.
> 	(c_parse_final_cleanups): Formatting fixes.
> 	* optimize.cc (can_alias_cdtor): Adjust condition, for
> 	HAVE_COMDAT_GROUP && DECL_ONE_ONLY && DECL_WEAK return true even
> 	if not DECL_INTERFACE_KNOWN.

> --- gcc/cp/optimize.cc.jj	2024-04-25 20:33:30.771858912 +0200
> +++ gcc/cp/optimize.cc	2024-05-09 17:10:23.920478922 +0200
> @@ -220,10 +220,8 @@ can_alias_cdtor (tree fn)
>     gcc_assert (DECL_MAYBE_IN_CHARGE_CDTOR_P (fn));
>     /* Don't use aliases for weak/linkonce definitions unless we can put both
>        symbols in the same COMDAT group.  */
> -  return (DECL_INTERFACE_KNOWN (fn)
> -	  && (SUPPORTS_ONE_ONLY || !DECL_WEAK (fn))
> -	  && (!DECL_ONE_ONLY (fn)
> -	      || (HAVE_COMDAT_GROUP && DECL_WEAK (fn))));
> +  return (DECL_WEAK (fn) ? (HAVE_COMDAT_GROUP && DECL_ONE_ONLY (fn))
> +			 : (DECL_INTERFACE_KNOWN (fn) && !DECL_ONE_ONLY (fn)));

Hmm, would

(DECL_ONE_ONLY (fn) ? HAVE_COMDAT_GROUP
  : (DECL_INTERFACE_KNOWN (fn) && !DECL_WEAK (fn)))

make sense instead?  I don't think DECL_WEAK is necessary for COMDAT.

Jason