>
> I am playing with doing some internal interface static analysis
> using the first patch below (and looking at LTO bootstrap results).
>
> An example, obvious patch resulting from that is the 2nd patch,
> resuling from the static analysis output
>
> /space/rguenther/src/svn/trunk/gcc/tree-ssa-pre.c:add_to_value can be made
> static
> /space/rguenther/src/svn/trunk/gcc/tree-ssa-pre.c:print_value_expressions
> can be made static
>
> the static analysis is very verbose (and does not consider ipa-refs yet).
> You also need to union results for building all frontends and all
> targets (well, in theory, or you can simply manually verify things
> which is a good idea anyway - even unused functions may be useful
> exported when they implement a generic data structure for example).
>
> Excercise for the reader: turn the analysis into a plugin.
>
> Richard.
>
>
> Index: gcc/lto/lto.c
> ===================================================================
> --- gcc/lto/lto.c (revision 185918)
> +++ gcc/lto/lto.c (working copy)
> @@ -2721,6 +2721,65 @@ read_cgraph_and_symbols (unsigned nfiles
> lto_symtab_merge_cgraph_nodes ();
> ggc_collect ();
>
> + if (flag_wpa)
> + {
> + struct cgraph_node *node;
> + FILE *f = fopen (concat (dump_base_name, ".callers", NULL), "w");
> + for (node = cgraph_nodes; node; node = node->next)
> + {
> + tree caller_tu = NULL_TREE;
> + struct cgraph_edge *caller;
> + bool found = true;
> +
> + if (!TREE_PUBLIC (node->decl)
> + || !TREE_STATIC (node->decl)
> + || resolution_used_from_other_file_p (node->resolution))
> + continue;
> +
> + if (!node->callers)
> + {
> + expanded_location loc = expand_location (DECL_SOURCE_LOCATION
> (node->decl));
> + fprintf (f, "%s:%s no calls\n",
> + loc.file, IDENTIFIER_POINTER (DECL_NAME (node->decl)));
> + }
With Mozilla folks I used the dumps from first WPA unreachable function removal
pass
with some degree of success. This gets a lot of non-trivial cases of dead code,
but also there are a lot of funny false positives wrt comdats etc.
> + for (caller = node->callers; caller; caller = caller->next_caller)
> + {
> + if (!caller_tu)
> + caller_tu = DECL_CONTEXT (caller->caller->decl);
> + else if (caller_tu
> + && DECL_CONTEXT (caller->caller->decl) != caller_tu)
> + found = false;
> + }
Extending to IPA-REF should be straighforward.
> + if (found && caller_tu)
> + {
> + expanded_location loc1 = expand_location (DECL_SOURCE_LOCATION
> (node->decl));
> + expanded_location loc2 = expand_location (DECL_SOURCE_LOCATION
> (node->callers->caller->decl));
> +
> + if (DECL_CONTEXT (node->decl) == caller_tu)
> + fprintf (f, "%s:%s can be made static\n",
> + loc1.file, IDENTIFIER_POINTER (DECL_NAME
> (node->decl)));
Indeed, this is also useful. Any plans to turn this into general -W<something>,
or you will also stay just with an internal hack like I did? :)
Honza
