Re: [PATCH, Pointer Bounds Checker 9/x] Cgraph extension

[Jeff Law <law@redhat.com>]

On 04/16/14 08:03, Ilya Enkovich wrote:
> Hi,
>
> This patch introduces changes in call graph for Pointer Bounds Checker.
>
> New fields instrumented_version, instrumentation_clone and orig_decl are added for cgraph_node:
>   - instrumentation_clone field is 1 for nodes created for instrumented version of functions
>   - instrumented_version points to instrumented/original node
>   - orig_decl holds original function declaration for instrumented nodes in case original node is removed
>
> IPA_REF_CHKP reference type is introduced for nodes to reference instrumented function versions from originals.  It is used to have proper reachability analysis.
>
> When original function bodies are not needed anymore, functions are transformed into thunks having call edge to the instrumented function.  Therefore new field appeared in cgraph_thunk_info to mark such thunks.
>
> Does it look OK?
>
> Bootstrapped and tested on linux-x86_64.
>
> Thanks,
> Ilya
> --
> gcc/
>
> 2014-04-16  Ilya Enkovich  <ilya.enkovich@intel.com>
>
> 	* cgraph.h (cgraph_thunk_info): Add add_pointer_bounds_args
> 	field.
> 	(cgraph_node): Add instrumented_version, orig_decl and
> 	instrumentation_clone fields.
> 	(symtab_alias_target): Allow IPA_REF_CHKP reference.
> 	* cgraph.c (cgraph_remove_node): Fix instrumented_version
> 	of the referenced node if any.
> 	(dump_cgraph_node): Dump instrumentation_clone and
> 	instrumented_version fields.
> 	(verify_cgraph_node): Check correctness of IPA_REF_CHKP
> 	references and instrumentation thunks.
> 	* cgraphbuild.c (rebuild_cgraph_edges): Rebuild IPA_REF_CHKP
> 	reference.
> 	(cgraph_rebuild_references): Likewise.
> 	* cgraphunit.c (assemble_thunks_and_aliases): Skip thunks
> 	calling instrumneted function version.
> 	* ipa-ref.h (ipa_ref_use): Add IPA_REF_CHKP.
> 	(ipa_ref): increase size of use field.
> 	* ipa-ref.c (ipa_ref_use_name): Add element for IPA_REF_CHKP.
> 	* lto-cgraph.c (lto_output_node): Output instrumentation_clone,
> 	thunk.add_pointer_bounds_args and orig_decl field.
> 	(lto_output_ref): Adjust to new ipa_ref::use field size.
> 	(input_overwrite_node): Read instrumentation_clone field.
> 	(input_node): Read thunk.add_pointer_bounds_args and orig_decl
> 	fields.
> 	(input_ref): Adjust to new ipa_ref::use field size.
> 	(input_cgraph_1): Compute instrumented_version fields and restore
> 	IDENTIFIER_TRANSPARENT_ALIAS chains.
> 	* lto-streamer.h (LTO_minor_version): Change minor version from
> 	0 to 1.
> 	* ipa.c (symtab_remove_unreachable_nodes): Consider instrumented
> 	clone as address taken if the original one is address taken.
> 	(cgraph_externally_visible_p): Mark instrumented 'main' as
> 	externally visible.
> 	(function_and_variable_visibility): Filter instrumentation
> 	thunks.
>
>
> diff --git a/gcc/cgraph.c b/gcc/cgraph.c
> index be3661a..6210c68 100644
> --- a/gcc/cgraph.c
> +++ b/gcc/cgraph.c
> @@ -2850,7 +2861,9 @@ verify_cgraph_node (struct cgraph_node *node)
>   	}
>         for (i = 0; ipa_ref_list_reference_iterate (&node->ref_list,
>   						  i, ref); i++)
> -	if (ref->use != IPA_REF_ALIAS)
> +	if (ref->use == IPA_REF_CHKP)
> +	  ;
> +	else if (ref->use != IPA_REF_ALIAS)
>   	  {
>   	    error ("Alias has non-alias reference");
>   	    error_found = true;
Is there any checking you can/should be doing here?    And I'm asking 
because I'm pretty sure there's something you ought to be checking here :-)

There's a general desire for key datastructures to sanity check them as 
much as possible.

> +  /* If instrumentation_clone is 1 then instrumented_version points
> +     to the original function used to make instrumented version.
> +     Otherwise points to instrumented version of the function.  */
> +  struct cgraph_node *instrumented_version;
> +  /* If instrumentation_clone is 1 then orig_decl is the original
> +     function declaration.  */
> +  tree orig_decl;
So I don't see anything which checks these two invariants.

Mostly it looks good.  I do want to look at it again once the 
verification stuff is beefed up.


Jeff