[PATCH v3] Use range-based for loops for traversing loops

[Martin Sebor]

On 7/23/21 2:35 AM, Kewen.Lin wrote:
> Hi,
> 
> Comparing to v2, this v3 removed the new CTOR with struct loops *loops
> as Richi clarified.  I'd like to support it in a separated follow up
> patch by extending the existing CTOR with an optional argument loop_p
> root.

Looks very nice (and quite a bit work)!  Thanks again!

Not to make even more work for you, but it occurred to me that
the declaration of the loop control variable could be simplified
by the use of auto like so:

   for (auto loop: loops_list (cfun, ...))

I spotted what looks to me like a few minor typos in the docs
diff:

diff --git a/gcc/doc/loop.texi b/gcc/doc/loop.texi
index a135656ed01..27697b08728 100644
--- a/gcc/doc/loop.texi
+++ b/gcc/doc/loop.texi
@@ -79,14 +79,14 @@ and its subloops in the numbering.  The index of a 
loop never changes.

  The entries of the @code{larray} field should not be accessed directly.
  The function @code{get_loop} returns the loop description for a loop with
-the given index.  @code{number_of_loops} function returns number of
-loops in the function.  To traverse all loops, use @code{FOR_EACH_LOOP}
-macro.  The @code{flags} argument of the macro is used to determine
-the direction of traversal and the set of loops visited.  Each loop is
-guaranteed to be visited exactly once, regardless of the changes to the
-loop tree, and the loops may be removed during the traversal.  The newly
-created loops are never traversed, if they need to be visited, this
-must be done separately after their creation.
+the given index.  @code{number_of_loops} function returns number of loops
+in the function.  To traverse all loops, use range-based for loop with

Missing article:

    use <ins>a </a>range-based for loop

+class @code{loop_list} instance. The @code{flags} argument of the macro

Is that loop_list or loops_list?

IIUC, it's also not a macro anymore, right?  The flags argument
is passed to the loop_list ctor, no?

Martin

> 
> Bootstrapped and regtested again on powerpc64le-linux-gnu P9,
> x86_64-redhat-linux and aarch64-linux-gnu, also
> bootstrapped again on ppc64le P9 with bootstrap-O3 config.
> 
> Is it ok for trunk?
> 
> BR,
> Kewen
> -----
> gcc/ChangeLog:
> 
> 	* cfgloop.h (as_const): New function.
> 	(class loop_iterator): Rename to ...
> 	(class loops_list): ... this.
> 	(loop_iterator::next): Rename to ...
> 	(loops_list::Iter::fill_curr_loop): ... this and adjust.
> 	(loop_iterator::loop_iterator): Rename to ...
> 	(loops_list::loops_list): ... this and adjust.
> 	(loops_list::Iter): New class.
> 	(loops_list::iterator): New type.
> 	(loops_list::const_iterator): New type.
> 	(loops_list::begin): New function.
> 	(loops_list::end): Likewise.
> 	(loops_list::begin const): Likewise.
> 	(loops_list::end const): Likewise.
> 	(FOR_EACH_LOOP): Remove.
> 	(FOR_EACH_LOOP_FN): Remove.
> 	* cfgloop.c (flow_loops_dump): Adjust FOR_EACH_LOOP* with range-based
> 	for loop with loops_list instance.
> 	(sort_sibling_loops): Likewise.
> 	(disambiguate_loops_with_multiple_latches): Likewise.
> 	(verify_loop_structure): Likewise.
> 	* cfgloopmanip.c (create_preheaders): Likewise.
> 	(force_single_succ_latches): Likewise.
> 	* config/aarch64/falkor-tag-collision-avoidance.c
> 	(execute_tag_collision_avoidance): Likewise.
> 	* config/mn10300/mn10300.c (mn10300_scan_for_setlb_lcc): Likewise.
> 	* config/s390/s390.c (s390_adjust_loops): Likewise.
> 	* doc/loop.texi: Likewise.
> 	* gimple-loop-interchange.cc (pass_linterchange::execute): Likewise.
> 	* gimple-loop-jam.c (tree_loop_unroll_and_jam): Likewise.
> 	* gimple-loop-versioning.cc (loop_versioning::analyze_blocks): Likewise.
> 	(loop_versioning::make_versioning_decisions): Likewise.
> 	* gimple-ssa-split-paths.c (split_paths): Likewise.
> 	* graphite-isl-ast-to-gimple.c (graphite_regenerate_ast_isl): Likewise.
> 	* graphite.c (canonicalize_loop_form): Likewise.
> 	(graphite_transform_loops): Likewise.
> 	* ipa-fnsummary.c (analyze_function_body): Likewise.
> 	* ipa-pure-const.c (analyze_function): Likewise.
> 	* loop-doloop.c (doloop_optimize_loops): Likewise.
> 	* loop-init.c (loop_optimizer_finalize): Likewise.
> 	(fix_loop_structure): Likewise.
> 	* loop-invariant.c (calculate_loop_reg_pressure): Likewise.
> 	(move_loop_invariants): Likewise.
> 	* loop-unroll.c (decide_unrolling): Likewise.
> 	(unroll_loops): Likewise.
> 	* modulo-sched.c (sms_schedule): Likewise.
> 	* predict.c (predict_loops): Likewise.
> 	(pass_profile::execute): Likewise.
> 	* profile.c (branch_prob): Likewise.
> 	* sel-sched-ir.c (sel_finish_pipelining): Likewise.
> 	(sel_find_rgns): Likewise.
> 	* tree-cfg.c (replace_loop_annotate): Likewise.
> 	(replace_uses_by): Likewise.
> 	(move_sese_region_to_fn): Likewise.
> 	* tree-if-conv.c (pass_if_conversion::execute): Likewise.
> 	* tree-loop-distribution.c (loop_distribution::execute): Likewise.
> 	* tree-parloops.c (parallelize_loops): Likewise.
> 	* tree-predcom.c (tree_predictive_commoning): Likewise.
> 	* tree-scalar-evolution.c (scev_initialize): Likewise.
> 	(scev_reset): Likewise.
> 	* tree-ssa-dce.c (find_obviously_necessary_stmts): Likewise.
> 	* tree-ssa-live.c (remove_unused_locals): Likewise.
> 	* tree-ssa-loop-ch.c (ch_base::copy_headers): Likewise.
> 	* tree-ssa-loop-im.c (analyze_memory_references): Likewise.
> 	(tree_ssa_lim_initialize): Likewise.
> 	* tree-ssa-loop-ivcanon.c (canonicalize_induction_variables): Likewise.
> 	* tree-ssa-loop-ivopts.c (tree_ssa_iv_optimize): Likewise.
> 	* tree-ssa-loop-manip.c (get_loops_exits): Likewise.
> 	* tree-ssa-loop-niter.c (estimate_numbers_of_iterations): Likewise.
> 	(free_numbers_of_iterations_estimates): Likewise.
> 	* tree-ssa-loop-prefetch.c (tree_ssa_prefetch_arrays): Likewise.
> 	* tree-ssa-loop-split.c (tree_ssa_split_loops): Likewise.
> 	* tree-ssa-loop-unswitch.c (tree_ssa_unswitch_loops): Likewise.
> 	* tree-ssa-loop.c (gate_oacc_kernels): Likewise.
> 	(pass_scev_cprop::execute): Likewise.
> 	* tree-ssa-propagate.c (clean_up_loop_closed_phi): Likewise.
> 	* tree-ssa-sccvn.c (do_rpo_vn): Likewise.
> 	* tree-ssa-threadupdate.c
> 	(jump_thread_path_registry::thread_through_all_blocks): Likewise.
> 	* tree-vectorizer.c (vectorize_loops): Likewise.
> 	* tree-vrp.c (vrp_asserts::find_assert_locations): Likewise.
>