Re: RFA (ipa-prop): PATCHes to avoid use of deprecated copy ctor and op=

[Martin Jambor]

Hi,

On Tue, May 15 2018, Jason Merrill wrote:
> In C++11 and up, the implicitly-declared copy constructor and
> assignment operator are deprecated if one of them, or the destructor,
> is user-provided.  Implementing that in G++ turned up a few dodgy uses
> in the compiler.
>
> In general it's unsafe to copy an ipa_edge_args, because if one of the
> pointers is non-null you get two copies of a vec pointer, and when one
> of the objects is destroyed it frees the vec and leaves the other
> object pointing to freed memory.  This specific example is safe
> because it only copies from an object with null pointers, but it would
> be better to avoid the copy.  OK for trunk?

I have had a look and found out that the function in question
(ipa_free_edge_args_substructures) has no uses, apparently I forgot to
remove it when I did the conversion of jump functions to be stored in
call graph edge summaries.  So thanks lot for spotting this but I'd
prefer the following (compiled but untested) patch:

Martin


2018-05-16  Martin Jambor  <mjam...@suse.cz>

        * ipa-prop.c (ipa_free_all_edge_args): Remove.
        * ipa-prop.h (ipa_free_all_edge_args): Likewise.


diff --git a/gcc/ipa-prop.c b/gcc/ipa-prop.c
index 38441cc49bc..19d55cda009 100644
--- a/gcc/ipa-prop.c
+++ b/gcc/ipa-prop.c
@@ -3708,16 +3708,6 @@ ipa_check_create_edge_args (void)
     ipa_vr_hash_table = hash_table<ipa_vr_ggc_hash_traits>::create_ggc (37);
 }
 
-/* Frees all dynamically allocated structures that the argument info points
-   to.  */
-
-void
-ipa_free_edge_args_substructures (struct ipa_edge_args *args)
-{
-  vec_free (args->jump_functions);
-  *args = ipa_edge_args ();
-}
-
 /* Free all ipa_edge structures.  */
 
 void
diff --git a/gcc/ipa-prop.h b/gcc/ipa-prop.h
index a61e06135e3..dc45cea9c71 100644
--- a/gcc/ipa-prop.h
+++ b/gcc/ipa-prop.h
@@ -664,7 +664,6 @@ extern GTY(()) vec<ipcp_transformation_summary, va_gc> 
*ipcp_transformations;
 void ipa_create_all_node_params (void);
 void ipa_create_all_edge_args (void);
 void ipa_check_create_edge_args (void);
-void ipa_free_edge_args_substructures (struct ipa_edge_args *);
 void ipa_free_all_node_params (void);
 void ipa_free_all_edge_args (void);
 void ipa_free_all_structures_after_ipa_cp (void);