> Hi,
>
> this patch fixes PR 60640 by creating thunks to clones when that is
> necessary to properly redirect edges to them. I mostly does what
> cgraph_add_thunk does and what analyze_function does to thunks. It
> fixes the testcases on trunk (it does not apply to 4.8, I have not
> looked how easily fixable that it) and passes bootstrap and testing on
> x86_64-linux.
>
> OK for trunk?
>
> Thanks,
>
> Martin
>
>
> 2014-03-26 Martin Jambor <mjam...@suse.cz>
>
> * cgraph.h (cgraph_clone_node): New parameter added to declaration.
> Adjust all callers.
> * cgraphclones.c (build_function_type_skip_args): Moved upwards in the
> file.
> (build_function_decl_skip_args): Likewise.
> (duplicate_thunk_for_node): New function.
> (redirect_edge_duplicating_thunks): Likewise.
> (cgraph_clone_node): New parameter args_to_skip, pass it to
> redirect_edge_duplicating_thunks which is called instead of
> cgraph_redirect_edge_callee.
> (cgraph_create_virtual_clone): Pass args_to_skip to cgraph_clone_node.
> +/* Duplicate thunk THUNK but make it to refer to NODE. ARGS_TO_SKIP, if
> + non-NULL, determines which parameters should be omitted. */
> +
> +static cgraph_node *
> +duplicate_thunk_for_node (cgraph_node *thunk, cgraph_node *node,
> + bitmap args_to_skip)
> +{
> + cgraph_node *new_thunk, *thunk_of;
> + thunk_of = cgraph_function_or_thunk_node (thunk->callees->callee);
> +
> + if (thunk_of->thunk.thunk_p)
> + node = duplicate_thunk_for_node (thunk_of, node, args_to_skip);
> +
> + tree new_decl;
> + if (!args_to_skip)
> + new_decl = copy_node (thunk->decl);
> + else
> + new_decl = build_function_decl_skip_args (thunk->decl, args_to_skip,
> false);
> +
> + gcc_checking_assert (!DECL_STRUCT_FUNCTION (new_decl));
> + gcc_checking_assert (!DECL_INITIAL (new_decl));
> + gcc_checking_assert (!DECL_RESULT (new_decl));
> + gcc_checking_assert (!DECL_RTL_SET_P (new_decl));
> +
> + DECL_NAME (new_decl) = clone_function_name (thunk->decl,
> "artificial_thunk");
> + SET_DECL_ASSEMBLER_NAME (new_decl, DECL_NAME (new_decl));
> + DECL_EXTERNAL (new_decl) = 0;
> + DECL_SECTION_NAME (new_decl) = NULL;
> + DECL_COMDAT_GROUP (new_decl) = 0;
> + TREE_PUBLIC (new_decl) = 0;
> + DECL_COMDAT (new_decl) = 0;
> + DECL_WEAK (new_decl) = 0;
> + DECL_VIRTUAL_P (new_decl) = 0;
> + DECL_STATIC_CONSTRUCTOR (new_decl) = 0;
> + DECL_STATIC_DESTRUCTOR (new_decl) = 0;
We probably ought to factor out this to common subfunction.
> +
> + new_thunk = cgraph_create_node (new_decl);
> + new_thunk->definition = true;
> + new_thunk->thunk = thunk->thunk;
> + new_thunk->unique_name = in_lto_p;
> + new_thunk->externally_visible = 0;
> + new_thunk->local.local = 1;
> + new_thunk->lowered = true;
> + new_thunk->former_clone_of = thunk->decl;
> +
> + struct cgraph_edge *e = cgraph_create_edge (new_thunk, node, NULL, 0,
> + CGRAPH_FREQ_BASE);
> + e->call_stmt_cannot_inline_p = true;
> + cgraph_call_edge_duplication_hooks (thunk->callees, e);
> + if (!expand_thunk (new_thunk, false))
> + new_thunk->analyzed = true;
> + cgraph_call_node_duplication_hooks (thunk, new_thunk);
> + return new_thunk;
> +}
> +
> +/* If E does not lead to a thunk, simply redirect it to N. Otherwise create
> + one or more equivalent thunks for N and redirect E to the first in the
> + chain. */
> +
> +void
> +redirect_edge_duplicating_thunks (struct cgraph_edge *e, struct cgraph_node
> *n,
> + bitmap args_to_skip)
> +{
> + cgraph_node *orig_to = cgraph_function_or_thunk_node (e->callee);
> + if (orig_to->thunk.thunk_p)
> + n = duplicate_thunk_for_node (orig_to, n, args_to_skip);
Is there anything that would pevent us from creating a new thunk for each call?
Also I think you need to avoid this logic when THIS parameter is being
optimized out
(i.e. it is part of skip_args)
Thanks for looking into this!
Honza
