Some projects need to prevent reordering of specific top level
declarations with LTO, in particular declarations defining init calls.
The only way to do that with LTO was to use -fno-toplevel-reorder,
which stops reordering for all declarations and makes LTO partitioning
less efficient.
This patch adds a new no_reorder attribute that stops reordering only
for the marked declaration. The program can then only mark e.g. the
initcalls and leave all the other declarations alone.
The patch does:
- Adds the new no_reorder attribute for the C family.
- Initializes a new no_reorder flag in the symtab_nodes in the
function visibility flag.
- Maintains the no_reorder flag when creating new nodes.
- Changes the partition code to always keep a separate
sorted queue of ordered nodes and flush them in order with the other
nodes. This is used by all nodes with -fno-toplevel-reorder,
and only the marked ones without it.
Parts of the old -fno-toplevel-reorder code paths are reused.
- Adds various checks throughout the tree to make no_reorder
marked functions behave the same as with -fno-toplevel-reorder
- Changes the LTO streamer to serialize the no_reorder attribute.
gcc/c-family/:
2014-09-23 Andi Kleen <ak@linux.intel.com>
* c-common.c (handle_no_reorder_attribute): New function.
(c_common_attribute_table): Add no_reorder attribute.
gcc/:
2014-09-23 Andi Kleen <ak@linux.intel.com>
* cgraph.h (symtab_node): Add no_reorder attribute.
(symbol_table::output_asm_statements): Remove.
* cgraphclones.c (cgraph_node::create_clone): Copy no_reorder.
(cgraph_node::create_version_clone): Dito.
(symbol_table::output_asm_statements): Remove.
* trans-mem.c (ipa_tm_create_version_alias): Dito.
* cgraphunit.c (varpool_node::finalize_decl): Check no_reorder.
(output_in_order): Add no_reorder flag. Only handle no_reorder
nodes when set.
(symbol_table::compile): Add separate pass for no_reorder nodes.
(process_common_attributes): Set no_reorder flag in symtab node.
Add node argument.
(process_function_and_variable_attributes): Pass symtab nodes to
process_common_attributes.
* doc/extend.texi (no_reorder): Document no_reorder attribute.
* lto-cgraph.c (lto_output_node): Serialize no_reorder.
(lto_output_varpool_node): Dito.
(input_overwrite_node): Dito.
(input_varpool_node): Dito.
* varpool.c (varpool_node::add): Set no_reorder attribute.
(symbol_table::remove_unreferenced_decls): Handle no_reorder.
(symbol_table::output_variables): Dito.
* symtab.c (symtab_node::dump_base): Print no_reorder.
gcc/lto/:
2014-09-23 Andi Kleen <ak@linux.intel.com>
* lto-partition.c (node_cmp): Update comment.
(varpool_node_cmp): Use symtab_node for comparison.
(add_sorted_nodes): New function.
(lto_balanced_map): Change to keep ordered queue
of ordered node. Handle no_reorder attribute.
From-SVN: r215537
