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

["Kewen.Lin" <linkw@linux.ibm.com>]

[-- Attachment #1: Type: text/plain, Size: 4337 bytes --]

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.

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.

[-- Attachment #2: range-based-v3.patch --]
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---
 gcc/cfgloop.c                                 |  19 +--
 gcc/cfgloop.h                                 | 140 +++++++++++++-----
 gcc/cfgloopmanip.c                            |   7 +-
 .../aarch64/falkor-tag-collision-avoidance.c  |   4 +-
 gcc/config/mn10300/mn10300.c                  |   4 +-
 gcc/config/s390/s390.c                        |   4 +-
 gcc/doc/loop.texi                             |  16 +-
 gcc/gimple-loop-interchange.cc                |   3 +-
 gcc/gimple-loop-jam.c                         |   3 +-
 gcc/gimple-loop-versioning.cc                 |   6 +-
 gcc/gimple-ssa-split-paths.c                  |   3 +-
 gcc/graphite-isl-ast-to-gimple.c              |   5 +-
 gcc/graphite.c                                |   6 +-
 gcc/ipa-fnsummary.c                           |   2 +-
 gcc/ipa-pure-const.c                          |   3 +-
 gcc/loop-doloop.c                             |   8 +-
 gcc/loop-init.c                               |   5 +-
 gcc/loop-invariant.c                          |  14 +-
 gcc/loop-unroll.c                             |   7 +-
 gcc/modulo-sched.c                            |   5 +-
 gcc/predict.c                                 |   5 +-
 gcc/profile.c                                 |   3 +-
 gcc/sel-sched-ir.c                            |  12 +-
 gcc/tree-cfg.c                                |  13 +-
 gcc/tree-if-conv.c                            |   3 +-
 gcc/tree-loop-distribution.c                  |   2 +-
 gcc/tree-parloops.c                           |   3 +-
 gcc/tree-predcom.c                            |   3 +-
 gcc/tree-scalar-evolution.c                   |  16 +-
 gcc/tree-ssa-dce.c                            |   3 +-
 gcc/tree-ssa-live.c                           |   3 +-
 gcc/tree-ssa-loop-ch.c                        |   3 +-
 gcc/tree-ssa-loop-im.c                        |   7 +-
 gcc/tree-ssa-loop-ivcanon.c                   |   3 +-
 gcc/tree-ssa-loop-ivopts.c                    |   3 +-
 gcc/tree-ssa-loop-manip.c                     |   3 +-
 gcc/tree-ssa-loop-niter.c                     |   8 +-
 gcc/tree-ssa-loop-prefetch.c                  |   3 +-
 gcc/tree-ssa-loop-split.c                     |   7 +-
 gcc/tree-ssa-loop-unswitch.c                  |   3 +-
 gcc/tree-ssa-loop.c                           |   6 +-
 gcc/tree-ssa-propagate.c                      |   3 +-
 gcc/tree-ssa-sccvn.c                          |   3 +-
 gcc/tree-ssa-threadupdate.c                   |   3 +-
 gcc/tree-vectorizer.c                         |   4 +-
 gcc/tree-vrp.c                                |   3 +-
 46 files changed, 195 insertions(+), 197 deletions(-)

diff --git a/gcc/cfgloop.c b/gcc/cfgloop.c
index f094538b9ff..d16591b2e1b 100644
--- a/gcc/cfgloop.c
+++ b/gcc/cfgloop.c
@@ -162,14 +162,12 @@ flow_loop_dump (const class loop *loop, FILE *file,
 void
 flow_loops_dump (FILE *file, void (*loop_dump_aux) (const class loop *, FILE *, int), int verbose)
 {
-  class loop *loop;
-
   if (!current_loops || ! file)
     return;
 
   fprintf (file, ";; %d loops found\n", number_of_loops (cfun));
 
-  FOR_EACH_LOOP (loop, LI_INCLUDE_ROOT)
+  for (class loop *loop : loops_list (cfun, LI_INCLUDE_ROOT))
     {
       flow_loop_dump (loop, file, loop_dump_aux, verbose);
     }
@@ -559,8 +557,7 @@ sort_sibling_loops (function *fn)
   free (rc_order);
 
   auto_vec<loop_p, 3> siblings;
-  loop_p loop;
-  FOR_EACH_LOOP_FN (fn, loop, LI_INCLUDE_ROOT)
+  for (class loop *loop : loops_list (fn, LI_INCLUDE_ROOT))
     if (loop->inner && loop->inner->next)
       {
 	loop_p sibling = loop->inner;
@@ -836,9 +833,7 @@ disambiguate_multiple_latches (class loop *loop)
 void
 disambiguate_loops_with_multiple_latches (void)
 {
-  class loop *loop;
-
-  FOR_EACH_LOOP (loop, 0)
+  for (class loop *loop : loops_list (cfun, 0))
     {
       if (!loop->latch)
 	disambiguate_multiple_latches (loop);
@@ -1457,7 +1452,7 @@ verify_loop_structure (void)
   auto_sbitmap visited (last_basic_block_for_fn (cfun));
   bitmap_clear (visited);
   bbs = XNEWVEC (basic_block, n_basic_blocks_for_fn (cfun));
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     {
       unsigned n;
 
@@ -1503,7 +1498,7 @@ verify_loop_structure (void)
   free (bbs);
 
   /* Check headers and latches.  */
-  FOR_EACH_LOOP (loop, 0)
+  for (class loop *loop : loops_list (cfun, 0))
     {
       i = loop->num;
       if (loop->header == NULL)
@@ -1629,7 +1624,7 @@ verify_loop_structure (void)
     }
 
   /* Check the recorded loop exits.  */
-  FOR_EACH_LOOP (loop, 0)
+  for (class loop *loop : loops_list (cfun, 0))
     {
       if (!loop->exits || loop->exits->e != NULL)
 	{
@@ -1723,7 +1718,7 @@ verify_loop_structure (void)
 	  err = 1;
 	}
 
-      FOR_EACH_LOOP (loop, 0)
+      for (class loop *loop : loops_list (cfun, 0))
 	{
 	  eloops = 0;
 	  for (exit = loop->exits->next; exit->e; exit = exit->next)
diff --git a/gcc/cfgloop.h b/gcc/cfgloop.h
index 5e699276c88..741df44ea51 100644
--- a/gcc/cfgloop.h
+++ b/gcc/cfgloop.h
@@ -658,55 +658,141 @@ enum li_flags
   LI_ONLY_INNERMOST = 4		/* Iterate only over innermost loops.  */
 };
 
-/* The iterator for loops.  */
+/* Provide the functionality of std::as_const to support range-based for
+   to use const iterator.  (We can't use std::as_const itself because it's
+   a C++17 feature.)  */
+template <typename T>
+constexpr const T &
+as_const (T &t)
+{
+  return t;
+}
+
+/* A list for visiting loops, which contains the loop numbers instead of
+   the loop pointers.  The scope is restricted in function FN and the
+   visiting order is specified by FLAGS.  */
 
-class loop_iterator
+class loops_list
 {
 public:
-  loop_iterator (function *fn, loop_p *loop, unsigned flags);
+  loops_list (function *fn, unsigned flags);
+
+  template <typename T> class Iter
+  {
+  public:
+    Iter (const loops_list &l, unsigned idx) : list (l), curr_idx (idx)
+    {
+      fill_curr_loop ();
+    }
+
+    T operator* () const { return curr_loop; }
+
+    Iter &
+    operator++ ()
+    {
+      if (curr_idx < list.to_visit.length ())
+	{
+	  /* Bump the index and fill a new one.  */
+	  curr_idx++;
+	  fill_curr_loop ();
+	}
+      else
+	gcc_assert (!curr_loop);
+
+      return *this;
+    }
+
+    bool
+    operator!= (const Iter &rhs) const
+    {
+      return this->curr_idx != rhs.curr_idx;
+    }
+
+  private:
+    /* Fill the current loop starting from the current index.  */
+    void fill_curr_loop ();
+
+    /* Reference to the loop list to visit.  */
+    const loops_list &list;
+
+    /* The current index in the list to visit.  */
+    unsigned curr_idx;
 
-  inline loop_p next ();
+    /* The loop implied by the current index.  */
+    loop_p curr_loop;
+  };
 
+  using iterator = Iter<loop_p>;
+  using const_iterator = Iter<const loop_p>;
+
+  iterator
+  begin ()
+  {
+    return iterator (*this, 0);
+  }
+
+  iterator
+  end ()
+  {
+    return iterator (*this, to_visit.length ());
+  }
+
+  const_iterator
+  begin () const
+  {
+    return const_iterator (*this, 0);
+  }
+
+  const_iterator
+  end () const
+  {
+    return const_iterator (*this, to_visit.length ());
+  }
+
+private:
   /* The function we are visiting.  */
   function *fn;
 
   /* The list of loops to visit.  */
   auto_vec<int, 16> to_visit;
-
-  /* The index of the actual loop.  */
-  unsigned idx;
 };
 
-inline loop_p
-loop_iterator::next ()
+/* Starting from current index CURR_IDX (inclusive), find one index
+   which stands for one valid loop and fill the found loop as CURR_LOOP,
+   if we can't find one, set CURR_LOOP as null.  */
+
+template <typename T>
+inline void
+loops_list::Iter<T>::fill_curr_loop ()
 {
   int anum;
 
-  while (this->to_visit.iterate (this->idx, &anum))
+  while (this->list.to_visit.iterate (this->curr_idx, &anum))
     {
-      this->idx++;
-      loop_p loop = get_loop (fn, anum);
+      loop_p loop = get_loop (this->list.fn, anum);
       if (loop)
-	return loop;
+	{
+	  curr_loop = loop;
+	  return;
+	}
+      this->curr_idx++;
     }
 
-  return NULL;
+  curr_loop = nullptr;
 }
 
-inline
-loop_iterator::loop_iterator (function *fn, loop_p *loop, unsigned flags)
+/* Set up the loops list to visit according to the specified
+   function scope FN and iterating order FLAGS.  */
+
+inline loops_list::loops_list (function *fn, unsigned flags)
 {
   class loop *aloop;
   unsigned i;
   int mn;
 
-  this->idx = 0;
   this->fn = fn;
   if (!loops_for_fn (fn))
-    {
-      *loop = NULL;
-      return;
-    }
+    return;
 
   this->to_visit.reserve_exact (number_of_loops (fn));
   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
@@ -766,20 +852,8 @@ loop_iterator::loop_iterator (function *fn, loop_p *loop, unsigned flags)
 	    }
 	}
     }
-
-  *loop = this->next ();
 }
 
-#define FOR_EACH_LOOP(LOOP, FLAGS) \
-  for (loop_iterator li(cfun, &(LOOP), FLAGS); \
-       (LOOP); \
-       (LOOP) = li.next ())
-
-#define FOR_EACH_LOOP_FN(FN, LOOP, FLAGS) \
-  for (loop_iterator li(FN, &(LOOP), FLAGS); \
-       (LOOP); \
-       (LOOP) = li.next ())
-
 /* The properties of the target.  */
 struct target_cfgloop {
   /* Number of available registers.  */
diff --git a/gcc/cfgloopmanip.c b/gcc/cfgloopmanip.c
index 2af59fedc92..28087a14e0f 100644
--- a/gcc/cfgloopmanip.c
+++ b/gcc/cfgloopmanip.c
@@ -1572,12 +1572,10 @@ create_preheader (class loop *loop, int flags)
 void
 create_preheaders (int flags)
 {
-  class loop *loop;
-
   if (!current_loops)
     return;
 
-  FOR_EACH_LOOP (loop, 0)
+  for (class loop *loop : loops_list (cfun, 0))
     create_preheader (loop, flags);
   loops_state_set (LOOPS_HAVE_PREHEADERS);
 }
@@ -1587,10 +1585,9 @@ create_preheaders (int flags)
 void
 force_single_succ_latches (void)
 {
-  class loop *loop;
   edge e;
 
-  FOR_EACH_LOOP (loop, 0)
+  for (class loop *loop : loops_list (cfun, 0))
     {
       if (loop->latch != loop->header && single_succ_p (loop->latch))
 	continue;
diff --git a/gcc/config/aarch64/falkor-tag-collision-avoidance.c b/gcc/config/aarch64/falkor-tag-collision-avoidance.c
index de214e4a0f7..d9b1b3fe835 100644
--- a/gcc/config/aarch64/falkor-tag-collision-avoidance.c
+++ b/gcc/config/aarch64/falkor-tag-collision-avoidance.c
@@ -808,8 +808,6 @@ record_loads (tag_map_t &tag_map, struct loop *loop)
 void
 execute_tag_collision_avoidance ()
 {
-  struct loop *loop;
-
   df_set_flags (DF_RD_PRUNE_DEAD_DEFS);
   df_chain_add_problem (DF_UD_CHAIN);
   df_compute_regs_ever_live (true);
@@ -824,7 +822,7 @@ execute_tag_collision_avoidance ()
   calculate_dominance_info (CDI_DOMINATORS);
   loop_optimizer_init (AVOID_CFG_MODIFICATIONS);
 
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     {
       tag_map_t tag_map (512);
 
diff --git a/gcc/config/mn10300/mn10300.c b/gcc/config/mn10300/mn10300.c
index 6f842a3ad32..d9229ff5cc6 100644
--- a/gcc/config/mn10300/mn10300.c
+++ b/gcc/config/mn10300/mn10300.c
@@ -3234,8 +3234,6 @@ mn10300_loop_contains_call_insn (loop_p loop)
 static void
 mn10300_scan_for_setlb_lcc (void)
 {
-  loop_p loop;
-
   DUMP ("Looking for loops that can use the SETLB insn", NULL_RTX);
 
   df_analyze ();
@@ -3248,7 +3246,7 @@ mn10300_scan_for_setlb_lcc (void)
      if an inner loop is not suitable for use with the SETLB/Lcc insns, it may
      be the case that its parent loop is suitable.  Thus we should check all
      loops, but work from the innermost outwards.  */
-  FOR_EACH_LOOP (loop, LI_ONLY_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_ONLY_INNERMOST))
     {
       const char * reason = NULL;
 
diff --git a/gcc/config/s390/s390.c b/gcc/config/s390/s390.c
index b1d3b99784d..a98e1beebf1 100644
--- a/gcc/config/s390/s390.c
+++ b/gcc/config/s390/s390.c
@@ -14479,15 +14479,13 @@ s390_adjust_loop_scan_osc (struct loop* loop)
 static void
 s390_adjust_loops ()
 {
-  struct loop *loop = NULL;
-
   df_analyze ();
   compute_bb_for_insn ();
 
   /* Find the loops.  */
   loop_optimizer_init (AVOID_CFG_MODIFICATIONS);
 
-  FOR_EACH_LOOP (loop, LI_ONLY_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_ONLY_INNERMOST))
     {
       if (dump_file)
 	{
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
+class @code{loop_list} instance. 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.
 
 Each basic block contains the reference to the innermost loop it belongs
 to (@code{loop_father}).  For this reason, it is only possible to have
diff --git a/gcc/gimple-loop-interchange.cc b/gcc/gimple-loop-interchange.cc
index 7a88faa2c07..a9044182a59 100644
--- a/gcc/gimple-loop-interchange.cc
+++ b/gcc/gimple-loop-interchange.cc
@@ -2089,8 +2089,7 @@ pass_linterchange::execute (function *fun)
     return 0;
 
   bool changed_p = false;
-  class loop *loop;
-  FOR_EACH_LOOP (loop, LI_ONLY_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_ONLY_INNERMOST))
     {
       vec<loop_p> loop_nest = vNULL;
       vec<data_reference_p> datarefs = vNULL;
diff --git a/gcc/gimple-loop-jam.c b/gcc/gimple-loop-jam.c
index 4842f0dff80..271139a1d87 100644
--- a/gcc/gimple-loop-jam.c
+++ b/gcc/gimple-loop-jam.c
@@ -486,13 +486,12 @@ adjust_unroll_factor (class loop *inner, struct data_dependence_relation *ddr,
 static unsigned int
 tree_loop_unroll_and_jam (void)
 {
-  class loop *loop;
   bool changed = false;
 
   gcc_assert (scev_initialized_p ());
 
   /* Go through all innermost loops.  */
-  FOR_EACH_LOOP (loop, LI_ONLY_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_ONLY_INNERMOST))
     {
       class loop *outer = loop_outer (loop);
 
diff --git a/gcc/gimple-loop-versioning.cc b/gcc/gimple-loop-versioning.cc
index 4b70c5a4aab..3fd086c0c65 100644
--- a/gcc/gimple-loop-versioning.cc
+++ b/gcc/gimple-loop-versioning.cc
@@ -1428,8 +1428,7 @@ loop_versioning::analyze_blocks ()
      versioning at that level could be useful in some cases.  */
   get_loop_info (get_loop (m_fn, 0)).rejected_p = true;
 
-  class loop *loop;
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     {
       loop_info &linfo = get_loop_info (loop);
 
@@ -1650,8 +1649,7 @@ loop_versioning::make_versioning_decisions ()
   AUTO_DUMP_SCOPE ("make_versioning_decisions",
 		   dump_user_location_t::from_function_decl (m_fn->decl));
 
-  class loop *loop;
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     {
       loop_info &linfo = get_loop_info (loop);
       if (decide_whether_loop_is_versionable (loop))
diff --git a/gcc/gimple-ssa-split-paths.c b/gcc/gimple-ssa-split-paths.c
index 2dd953d5ef9..1470de279d6 100644
--- a/gcc/gimple-ssa-split-paths.c
+++ b/gcc/gimple-ssa-split-paths.c
@@ -473,13 +473,12 @@ static bool
 split_paths ()
 {
   bool changed = false;
-  loop_p loop;
 
   loop_optimizer_init (LOOPS_NORMAL | LOOPS_HAVE_RECORDED_EXITS);
   initialize_original_copy_tables ();
   calculate_dominance_info (CDI_DOMINATORS);
 
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     {
       /* Only split paths if we are optimizing this loop for speed.  */
       if (!optimize_loop_for_speed_p (loop))
diff --git a/gcc/graphite-isl-ast-to-gimple.c b/gcc/graphite-isl-ast-to-gimple.c
index c202213f39b..30370859460 100644
--- a/gcc/graphite-isl-ast-to-gimple.c
+++ b/gcc/graphite-isl-ast-to-gimple.c
@@ -1535,9 +1535,8 @@ graphite_regenerate_ast_isl (scop_p scop)
       if_region->false_region->region.entry->flags |= EDGE_FALLTHRU;
       /* remove_edge_and_dominated_blocks marks loops for removal but
 	 doesn't actually remove them (fix that...).  */
-      loop_p loop;
-      FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
-	if (! loop->header)
+      for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
+	if (!loop->header)
 	  delete_loop (loop);
     }
 
diff --git a/gcc/graphite.c b/gcc/graphite.c
index 6c4fb42282b..a26d5a3a818 100644
--- a/gcc/graphite.c
+++ b/gcc/graphite.c
@@ -377,8 +377,7 @@ canonicalize_loop_closed_ssa (loop_p loop, edge e)
 static void
 canonicalize_loop_form (void)
 {
-  loop_p loop;
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     {
       edge e = single_exit (loop);
       if (!e || (e->flags & (EDGE_COMPLEX|EDGE_FAKE)))
@@ -494,10 +493,9 @@ graphite_transform_loops (void)
 
   if (dump_file && (dump_flags & TDF_DETAILS))
     {
-      loop_p loop;
       int num_no_dependency = 0;
 
-      FOR_EACH_LOOP (loop, 0)
+      for (class loop *loop : loops_list (cfun, 0))
 	if (loop->can_be_parallel)
 	  num_no_dependency++;
 
diff --git a/gcc/ipa-fnsummary.c b/gcc/ipa-fnsummary.c
index 95d28757f95..883773abe12 100644
--- a/gcc/ipa-fnsummary.c
+++ b/gcc/ipa-fnsummary.c
@@ -2923,7 +2923,7 @@ analyze_function_body (struct cgraph_node *node, bool early)
       if (dump_file && (dump_flags & TDF_DETAILS))
 	flow_loops_dump (dump_file, NULL, 0);
       scev_initialize ();
-      FOR_EACH_LOOP (loop, 0)
+      for (class loop *loop : loops_list (cfun, 0))
 	{
 	  predicate loop_iterations = true;
 	  sreal header_freq;
diff --git a/gcc/ipa-pure-const.c b/gcc/ipa-pure-const.c
index f045108af21..f1724e4f46d 100644
--- a/gcc/ipa-pure-const.c
+++ b/gcc/ipa-pure-const.c
@@ -1087,9 +1087,8 @@ end:
 	    }
 	  else
 	    {
-	      class loop *loop;
 	      scev_initialize ();
-	      FOR_EACH_LOOP (loop, 0)
+	      for (class loop *loop : loops_list (cfun, 0))
 		if (!finite_loop_p (loop))
 		  {
 		    if (dump_file)
diff --git a/gcc/loop-doloop.c b/gcc/loop-doloop.c
index dda7b9e268f..12288bd64d8 100644
--- a/gcc/loop-doloop.c
+++ b/gcc/loop-doloop.c
@@ -789,18 +789,14 @@ doloop_optimize (class loop *loop)
 void
 doloop_optimize_loops (void)
 {
-  class loop *loop;
-
   if (optimize == 1)
     {
       df_live_add_problem ();
       df_live_set_all_dirty ();
     }
 
-  FOR_EACH_LOOP (loop, 0)
-    {
-      doloop_optimize (loop);
-    }
+  for (class loop *loop : loops_list (cfun, 0))
+    doloop_optimize (loop);
 
   if (optimize == 1)
     df_remove_problem (df_live);
diff --git a/gcc/loop-init.c b/gcc/loop-init.c
index 1fde0ede441..1f75f509f53 100644
--- a/gcc/loop-init.c
+++ b/gcc/loop-init.c
@@ -137,7 +137,6 @@ loop_optimizer_init (unsigned flags)
 void
 loop_optimizer_finalize (struct function *fn, bool clean_loop_closed_phi)
 {
-  class loop *loop;
   basic_block bb;
 
   timevar_push (TV_LOOP_FINI);
@@ -167,7 +166,7 @@ loop_optimizer_finalize (struct function *fn, bool clean_loop_closed_phi)
       goto loop_fini_done;
     }
 
-  FOR_EACH_LOOP_FN (fn, loop, 0)
+  for (class loop *loop : loops_list (fn, 0))
     free_simple_loop_desc (loop);
 
   /* Clean up.  */
@@ -229,7 +228,7 @@ fix_loop_structure (bitmap changed_bbs)
      loops, so that when we remove the loops, we know that the loops inside
      are preserved, and do not waste time relinking loops that will be
      removed later.  */
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     {
       /* Detect the case that the loop is no longer present even though
          it wasn't marked for removal.
diff --git a/gcc/loop-invariant.c b/gcc/loop-invariant.c
index bdc7b59dd5f..059ef8fe7f4 100644
--- a/gcc/loop-invariant.c
+++ b/gcc/loop-invariant.c
@@ -2136,7 +2136,7 @@ calculate_loop_reg_pressure (void)
   rtx link;
   class loop *loop, *parent;
 
-  FOR_EACH_LOOP (loop, 0)
+  for (class loop *loop : loops_list (cfun, 0))
     if (loop->aux == NULL)
       {
 	loop->aux = xcalloc (1, sizeof (class loop_data));
@@ -2203,7 +2203,7 @@ calculate_loop_reg_pressure (void)
   bitmap_release (&curr_regs_live);
   if (flag_ira_region == IRA_REGION_MIXED
       || flag_ira_region == IRA_REGION_ALL)
-    FOR_EACH_LOOP (loop, 0)
+    for (class loop *loop : loops_list (cfun, 0))
       {
 	EXECUTE_IF_SET_IN_BITMAP (&LOOP_DATA (loop)->regs_live, 0, j, bi)
 	  if (! bitmap_bit_p (&LOOP_DATA (loop)->regs_ref, j))
@@ -2217,7 +2217,7 @@ calculate_loop_reg_pressure (void)
       }
   if (dump_file == NULL)
     return;
-  FOR_EACH_LOOP (loop, 0)
+  for (class loop *loop : loops_list (cfun, 0))
     {
       parent = loop_outer (loop);
       fprintf (dump_file, "\n  Loop %d (parent %d, header bb%d, depth %d)\n",
@@ -2251,8 +2251,6 @@ calculate_loop_reg_pressure (void)
 void
 move_loop_invariants (void)
 {
-  class loop *loop;
-
   if (optimize == 1)
     df_live_add_problem ();
   /* ??? This is a hack.  We should only need to call df_live_set_all_dirty
@@ -2271,7 +2269,7 @@ move_loop_invariants (void)
     }
   df_set_flags (DF_EQ_NOTES + DF_DEFER_INSN_RESCAN);
   /* Process the loops, innermost first.  */
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     {
       curr_loop = loop;
       /* move_single_loop_invariants for very large loops is time consuming
@@ -2284,10 +2282,8 @@ move_loop_invariants (void)
 	move_single_loop_invariants (loop);
     }
 
-  FOR_EACH_LOOP (loop, 0)
-    {
+  for (class loop *loop : loops_list (cfun, 0))
       free_loop_data (loop);
-    }
 
   if (flag_ira_loop_pressure)
     /* There is no sense to keep this info because it was most
diff --git a/gcc/loop-unroll.c b/gcc/loop-unroll.c
index 66d93487e29..f11c9c396ae 100644
--- a/gcc/loop-unroll.c
+++ b/gcc/loop-unroll.c
@@ -214,10 +214,8 @@ report_unroll (class loop *loop, dump_location_t locus)
 static void
 decide_unrolling (int flags)
 {
-  class loop *loop;
-
   /* Scan the loops, inner ones first.  */
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     {
       loop->lpt_decision.decision = LPT_NONE;
       dump_user_location_t locus = get_loop_location (loop);
@@ -278,14 +276,13 @@ decide_unrolling (int flags)
 void
 unroll_loops (int flags)
 {
-  class loop *loop;
   bool changed = false;
 
   /* Now decide rest of unrolling.  */
   decide_unrolling (flags);
 
   /* Scan the loops, inner ones first.  */
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     {
       /* And perform the appropriate transformations.  */
       switch (loop->lpt_decision.decision)
diff --git a/gcc/modulo-sched.c b/gcc/modulo-sched.c
index e72e46db387..fc761cf60c5 100644
--- a/gcc/modulo-sched.c
+++ b/gcc/modulo-sched.c
@@ -1353,7 +1353,6 @@ sms_schedule (void)
   int maxii, max_asap;
   partial_schedule_ptr ps;
   basic_block bb = NULL;
-  class loop *loop;
   basic_block condition_bb = NULL;
   edge latch_edge;
   HOST_WIDE_INT trip_count, max_trip_count;
@@ -1397,7 +1396,7 @@ sms_schedule (void)
 
   /* Build DDGs for all the relevant loops and hold them in G_ARR
      indexed by the loop index.  */
-  FOR_EACH_LOOP (loop, 0)
+  for (class loop *loop : loops_list (cfun, 0))
     {
       rtx_insn *head, *tail;
       rtx count_reg;
@@ -1543,7 +1542,7 @@ sms_schedule (void)
   }
 
   /* We don't want to perform SMS on new loops - created by versioning.  */
-  FOR_EACH_LOOP (loop, 0)
+  for (class loop *loop : loops_list (cfun, 0))
     {
       rtx_insn *head, *tail;
       rtx count_reg;
diff --git a/gcc/predict.c b/gcc/predict.c
index d751e6cecce..5876b6e44a8 100644
--- a/gcc/predict.c
+++ b/gcc/predict.c
@@ -1949,7 +1949,7 @@ predict_loops (void)
 
   /* Try to predict out blocks in a loop that are not part of a
      natural loop.  */
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     {
       basic_block bb, *bbs;
       unsigned j, n_exits = 0;
@@ -4111,8 +4111,7 @@ pass_profile::execute (function *fun)
     profile_status_for_fn (fun) = PROFILE_GUESSED;
  if (dump_file && (dump_flags & TDF_DETAILS))
    {
-     class loop *loop;
-     FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+     for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
        if (loop->header->count.initialized_p ())
          fprintf (dump_file, "Loop got predicted %d to iterate %i times.\n",
        	   loop->num,
diff --git a/gcc/profile.c b/gcc/profile.c
index 1fa4196fa16..6357fb37cfd 100644
--- a/gcc/profile.c
+++ b/gcc/profile.c
@@ -1466,13 +1466,12 @@ branch_prob (bool thunk)
   if (flag_branch_probabilities
       && (profile_status_for_fn (cfun) == PROFILE_READ))
     {
-      class loop *loop;
       if (dump_file && (dump_flags & TDF_DETAILS))
 	report_predictor_hitrates ();
 
       /* At this moment we have precise loop iteration count estimates.
 	 Record them to loop structure before the profile gets out of date. */
-      FOR_EACH_LOOP (loop, 0)
+      for (class loop *loop : loops_list (cfun, 0))
 	if (loop->header->count > 0 && loop->header->count.reliable_p ())
 	  {
 	    gcov_type nit = expected_loop_iterations_unbounded (loop);
diff --git a/gcc/sel-sched-ir.c b/gcc/sel-sched-ir.c
index eef9d6969f4..3dff69f21ce 100644
--- a/gcc/sel-sched-ir.c
+++ b/gcc/sel-sched-ir.c
@@ -6247,10 +6247,8 @@ make_regions_from_the_rest (void)
 /* Free data structures used in pipelining of loops.  */
 void sel_finish_pipelining (void)
 {
-  class loop *loop;
-
   /* Release aux fields so we don't free them later by mistake.  */
-  FOR_EACH_LOOP (loop, 0)
+  for (class loop *loop : loops_list (cfun, 0))
     loop->aux = NULL;
 
   loop_optimizer_finalize ();
@@ -6271,11 +6269,11 @@ sel_find_rgns (void)
 
   if (current_loops)
     {
-      loop_p loop;
+      unsigned flags = flag_sel_sched_pipelining_outer_loops
+			 ? LI_FROM_INNERMOST
+			 : LI_ONLY_INNERMOST;
 
-      FOR_EACH_LOOP (loop, (flag_sel_sched_pipelining_outer_loops
-			    ? LI_FROM_INNERMOST
-			    : LI_ONLY_INNERMOST))
+      for (class loop *loop : loops_list (cfun, flags))
 	make_regions_from_loop_nest (loop);
     }
 
diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index c8b0f7b33e1..0d082851f2f 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -312,12 +312,11 @@ replace_loop_annotate_in_block (basic_block bb, class loop *loop)
 static void
 replace_loop_annotate (void)
 {
-  class loop *loop;
   basic_block bb;
   gimple_stmt_iterator gsi;
   gimple *stmt;
 
-  FOR_EACH_LOOP (loop, 0)
+  for (class loop *loop : loops_list (cfun, 0))
     {
       /* First look into the header.  */
       replace_loop_annotate_in_block (loop->header, loop);
@@ -2027,12 +2026,8 @@ replace_uses_by (tree name, tree val)
   /* Also update the trees stored in loop structures.  */
   if (current_loops)
     {
-      class loop *loop;
-
-      FOR_EACH_LOOP (loop, 0)
-	{
+      for (class loop *loop : loops_list (cfun, 0))
 	  substitute_in_loop_info (loop, name, val);
-	}
     }
 }
 
@@ -7752,9 +7747,9 @@ move_sese_region_to_fn (struct function *dest_cfun, basic_block entry_bb,
 
   /* Fix up orig_loop_num.  If the block referenced in it has been moved
      to dest_cfun, update orig_loop_num field, otherwise clear it.  */
-  class loop *dloop;
+  class loop *dloop = NULL;
   signed char *moved_orig_loop_num = NULL;
-  FOR_EACH_LOOP_FN (dest_cfun, dloop, 0)
+  for (class loop *dloop : loops_list (dest_cfun, 0))
     if (dloop->orig_loop_num)
       {
 	if (moved_orig_loop_num == NULL)
diff --git a/gcc/tree-if-conv.c b/gcc/tree-if-conv.c
index 345488e2a19..1bf68455f72 100644
--- a/gcc/tree-if-conv.c
+++ b/gcc/tree-if-conv.c
@@ -3300,14 +3300,13 @@ pass_if_conversion::gate (function *fun)
 unsigned int
 pass_if_conversion::execute (function *fun)
 {
-  class loop *loop;
   unsigned todo = 0;
 
   if (number_of_loops (fun) <= 1)
     return 0;
 
   auto_vec<gimple *> preds;
-  FOR_EACH_LOOP (loop, 0)
+  for (class loop *loop : loops_list (cfun, 0))
     if (flag_tree_loop_if_convert == 1
 	|| ((flag_tree_loop_vectorize || loop->force_vectorize)
 	    && !loop->dont_vectorize))
diff --git a/gcc/tree-loop-distribution.c b/gcc/tree-loop-distribution.c
index 65aa1df4aba..1f0b6eb3a95 100644
--- a/gcc/tree-loop-distribution.c
+++ b/gcc/tree-loop-distribution.c
@@ -3312,7 +3312,7 @@ loop_distribution::execute (function *fun)
 
   /* We can at the moment only distribute non-nested loops, thus restrict
      walking to innermost loops.  */
-  FOR_EACH_LOOP (loop, LI_ONLY_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_ONLY_INNERMOST))
     {
       /* Don't distribute multiple exit edges loop, or cold loop when
          not doing pattern detection.  */
diff --git a/gcc/tree-parloops.c b/gcc/tree-parloops.c
index fe1baef32a7..9d73f241204 100644
--- a/gcc/tree-parloops.c
+++ b/gcc/tree-parloops.c
@@ -3989,7 +3989,6 @@ parallelize_loops (bool oacc_kernels_p)
 {
   unsigned n_threads;
   bool changed = false;
-  class loop *loop;
   class loop *skip_loop = NULL;
   class tree_niter_desc niter_desc;
   struct obstack parloop_obstack;
@@ -4020,7 +4019,7 @@ parallelize_loops (bool oacc_kernels_p)
 
   calculate_dominance_info (CDI_DOMINATORS);
 
-  FOR_EACH_LOOP (loop, 0)
+  for (class loop *loop : loops_list (cfun, 0))
     {
       if (loop == skip_loop)
 	{
diff --git a/gcc/tree-predcom.c b/gcc/tree-predcom.c
index cf85517e1c7..b8ae6b66df9 100644
--- a/gcc/tree-predcom.c
+++ b/gcc/tree-predcom.c
@@ -3419,11 +3419,10 @@ pcom_worker::tree_predictive_commoning_loop (bool allow_unroll_p)
 unsigned
 tree_predictive_commoning (bool allow_unroll_p)
 {
-  class loop *loop;
   unsigned ret = 0, changed = 0;
 
   initialize_original_copy_tables ();
-  FOR_EACH_LOOP (loop, LI_ONLY_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_ONLY_INNERMOST))
     if (optimize_loop_for_speed_p (loop))
       {
 	pcom_worker w(loop);
diff --git a/gcc/tree-scalar-evolution.c b/gcc/tree-scalar-evolution.c
index b22d49a0ab6..c6a3b7f9bd7 100644
--- a/gcc/tree-scalar-evolution.c
+++ b/gcc/tree-scalar-evolution.c
@@ -2977,16 +2977,12 @@ gather_stats_on_scev_database (void)
 void
 scev_initialize (void)
 {
-  class loop *loop;
-
   gcc_assert (! scev_initialized_p ());
 
   scalar_evolution_info = hash_table<scev_info_hasher>::create_ggc (100);
 
-  FOR_EACH_LOOP (loop, 0)
-    {
-      loop->nb_iterations = NULL_TREE;
-    }
+  for (class loop *loop : loops_list (cfun, 0))
+    loop->nb_iterations = NULL_TREE;
 }
 
 /* Return true if SCEV is initialized.  */
@@ -3015,14 +3011,10 @@ scev_reset_htab (void)
 void
 scev_reset (void)
 {
-  class loop *loop;
-
   scev_reset_htab ();
 
-  FOR_EACH_LOOP (loop, 0)
-    {
-      loop->nb_iterations = NULL_TREE;
-    }
+  for (class loop *loop : loops_list (cfun, 0))
+    loop->nb_iterations = NULL_TREE;
 }
 
 /* Return true if the IV calculation in TYPE can overflow based on the knowledge
diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c
index e2d3b63a30c..226cbc18a2f 100644
--- a/gcc/tree-ssa-dce.c
+++ b/gcc/tree-ssa-dce.c
@@ -417,7 +417,6 @@ find_obviously_necessary_stmts (bool aggressive)
   /* Prevent the empty possibly infinite loops from being removed.  */
   if (aggressive)
     {
-      class loop *loop;
       if (mark_irreducible_loops ())
 	FOR_EACH_BB_FN (bb, cfun)
 	  {
@@ -433,7 +432,7 @@ find_obviously_necessary_stmts (bool aggressive)
 		}
 	  }
 
-      FOR_EACH_LOOP (loop, 0)
+      for (class loop *loop : loops_list (cfun, 0))
 	if (!finite_loop_p (loop))
 	  {
 	    if (dump_file)
diff --git a/gcc/tree-ssa-live.c b/gcc/tree-ssa-live.c
index a2aab25e862..16a3f7bb0bb 100644
--- a/gcc/tree-ssa-live.c
+++ b/gcc/tree-ssa-live.c
@@ -908,8 +908,7 @@ remove_unused_locals (void)
 
   if (cfun->has_simduid_loops)
     {
-      class loop *loop;
-      FOR_EACH_LOOP (loop, 0)
+      for (class loop *loop : loops_list (cfun, 0))
 	if (loop->simduid && !is_used_p (loop->simduid))
 	  loop->simduid = NULL_TREE;
     }
diff --git a/gcc/tree-ssa-loop-ch.c b/gcc/tree-ssa-loop-ch.c
index dfa5dc87c34..57fa3ee3608 100644
--- a/gcc/tree-ssa-loop-ch.c
+++ b/gcc/tree-ssa-loop-ch.c
@@ -348,7 +348,6 @@ protected:
 unsigned int
 ch_base::copy_headers (function *fun)
 {
-  class loop *loop;
   basic_block header;
   edge exit, entry;
   basic_block *bbs, *copied_bbs;
@@ -365,7 +364,7 @@ ch_base::copy_headers (function *fun)
 
   auto_vec<std::pair<edge, loop_p> > copied;
 
-  FOR_EACH_LOOP (loop, 0)
+  for (class loop *loop : loops_list (cfun, 0))
     {
       int initial_limit = param_max_loop_header_insns;
       int remaining_limit = initial_limit;
diff --git a/gcc/tree-ssa-loop-im.c b/gcc/tree-ssa-loop-im.c
index 81b4ec21d6e..a8cc9bc8151 100644
--- a/gcc/tree-ssa-loop-im.c
+++ b/gcc/tree-ssa-loop-im.c
@@ -1662,7 +1662,7 @@ analyze_memory_references (bool store_motion)
 {
   gimple_stmt_iterator bsi;
   basic_block bb, *bbs;
-  class loop *loop, *outer;
+  class loop *outer;
   unsigned i, n;
 
   /* Collect all basic-blocks in loops and sort them after their
@@ -1706,7 +1706,7 @@ analyze_memory_references (bool store_motion)
 
   /* Propagate the information about accessed memory references up
      the loop hierarchy.  */
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     {
       /* Finalize the overall touched references (including subloops).  */
       bitmap_ior_into (&memory_accesses.all_refs_stored_in_loop[loop->num],
@@ -3133,7 +3133,6 @@ fill_always_executed_in (void)
 static void
 tree_ssa_lim_initialize (bool store_motion)
 {
-  class loop *loop;
   unsigned i;
 
   bitmap_obstack_initialize (&lim_bitmap_obstack);
@@ -3177,7 +3176,7 @@ tree_ssa_lim_initialize (bool store_motion)
      its postorder index.  */
   i = 0;
   bb_loop_postorder = XNEWVEC (unsigned, number_of_loops (cfun));
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     bb_loop_postorder[loop->num] = i++;
 }
 
diff --git a/gcc/tree-ssa-loop-ivcanon.c b/gcc/tree-ssa-loop-ivcanon.c
index b1971f83544..81e9a22be4c 100644
--- a/gcc/tree-ssa-loop-ivcanon.c
+++ b/gcc/tree-ssa-loop-ivcanon.c
@@ -1285,14 +1285,13 @@ canonicalize_loop_induction_variables (class loop *loop,
 unsigned int
 canonicalize_induction_variables (void)
 {
-  class loop *loop;
   bool changed = false;
   bool irred_invalidated = false;
   bitmap loop_closed_ssa_invalidated = BITMAP_ALLOC (NULL);
 
   estimate_numbers_of_iterations (cfun);
 
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     {
       changed |= canonicalize_loop_induction_variables (loop,
 							true, UL_SINGLE_ITER,
diff --git a/gcc/tree-ssa-loop-ivopts.c b/gcc/tree-ssa-loop-ivopts.c
index 12a8a49a307..43668463b21 100644
--- a/gcc/tree-ssa-loop-ivopts.c
+++ b/gcc/tree-ssa-loop-ivopts.c
@@ -8066,14 +8066,13 @@ finish:
 void
 tree_ssa_iv_optimize (void)
 {
-  class loop *loop;
   struct ivopts_data data;
   auto_bitmap toremove;
 
   tree_ssa_iv_optimize_init (&data);
 
   /* Optimize the loops starting with the innermost ones.  */
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     {
       if (!dbg_cnt (ivopts_loop))
 	continue;
diff --git a/gcc/tree-ssa-loop-manip.c b/gcc/tree-ssa-loop-manip.c
index 28ae1316fa0..15dab0c1451 100644
--- a/gcc/tree-ssa-loop-manip.c
+++ b/gcc/tree-ssa-loop-manip.c
@@ -362,11 +362,10 @@ add_exit_phis (bitmap names_to_rename, bitmap *use_blocks, bitmap *loop_exits)
 static void
 get_loops_exits (bitmap *loop_exits)
 {
-  class loop *loop;
   unsigned j;
   edge e;
 
-  FOR_EACH_LOOP (loop, 0)
+  for (class loop *loop : loops_list (cfun, 0))
     {
       auto_vec<edge> exit_edges = get_loop_exit_edges (loop);
       loop_exits[loop->num] = BITMAP_ALLOC (&loop_renamer_obstack);
diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c
index 6fabf10a215..84e5ce064fe 100644
--- a/gcc/tree-ssa-loop-niter.c
+++ b/gcc/tree-ssa-loop-niter.c
@@ -4559,13 +4559,11 @@ estimated_stmt_executions (class loop *loop, widest_int *nit)
 void
 estimate_numbers_of_iterations (function *fn)
 {
-  class loop *loop;
-
   /* We don't want to issue signed overflow warnings while getting
      loop iteration estimates.  */
   fold_defer_overflow_warnings ();
 
-  FOR_EACH_LOOP_FN (fn, loop, 0)
+  for (class loop *loop : loops_list (fn, 0))
     estimate_numbers_of_iterations (loop);
 
   fold_undefer_and_ignore_overflow_warnings ();
@@ -5031,9 +5029,7 @@ free_numbers_of_iterations_estimates (class loop *loop)
 void
 free_numbers_of_iterations_estimates (function *fn)
 {
-  class loop *loop;
-
-  FOR_EACH_LOOP_FN (fn, loop, 0)
+  for (class loop *loop : loops_list (fn, 0))
     free_numbers_of_iterations_estimates (loop);
 }
 
diff --git a/gcc/tree-ssa-loop-prefetch.c b/gcc/tree-ssa-loop-prefetch.c
index 98062eb4616..b1af922d403 100644
--- a/gcc/tree-ssa-loop-prefetch.c
+++ b/gcc/tree-ssa-loop-prefetch.c
@@ -1980,7 +1980,6 @@ fail:
 unsigned int
 tree_ssa_prefetch_arrays (void)
 {
-  class loop *loop;
   bool unrolled = false;
   int todo_flags = 0;
 
@@ -2025,7 +2024,7 @@ tree_ssa_prefetch_arrays (void)
       set_builtin_decl (BUILT_IN_PREFETCH, decl, false);
     }
 
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     {
       if (dump_file && (dump_flags & TDF_DETAILS))
 	fprintf (dump_file, "Processing loop %d:\n", loop->num);
diff --git a/gcc/tree-ssa-loop-split.c b/gcc/tree-ssa-loop-split.c
index 3a09bbc39e5..40629227863 100644
--- a/gcc/tree-ssa-loop-split.c
+++ b/gcc/tree-ssa-loop-split.c
@@ -1598,18 +1598,17 @@ split_loop_on_cond (struct loop *loop)
 static unsigned int
 tree_ssa_split_loops (void)
 {
-  class loop *loop;
   bool changed = false;
 
   gcc_assert (scev_initialized_p ());
 
   calculate_dominance_info (CDI_POST_DOMINATORS);
 
-  FOR_EACH_LOOP (loop, LI_INCLUDE_ROOT)
+  for (class loop *loop : loops_list (cfun, LI_INCLUDE_ROOT))
     loop->aux = NULL;
 
   /* Go through all loops starting from innermost.  */
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     {
       if (loop->aux)
 	{
@@ -1630,7 +1629,7 @@ tree_ssa_split_loops (void)
 	}
     }
 
-  FOR_EACH_LOOP (loop, LI_INCLUDE_ROOT)
+  for (class loop *loop : loops_list (cfun, LI_INCLUDE_ROOT))
     loop->aux = NULL;
 
   clear_aux_for_blocks ();
diff --git a/gcc/tree-ssa-loop-unswitch.c b/gcc/tree-ssa-loop-unswitch.c
index 04d4553f13e..c4adb52a67c 100644
--- a/gcc/tree-ssa-loop-unswitch.c
+++ b/gcc/tree-ssa-loop-unswitch.c
@@ -90,11 +90,10 @@ static tree get_vop_from_header (class loop *);
 unsigned int
 tree_ssa_unswitch_loops (void)
 {
-  class loop *loop;
   bool changed = false;
 
   /* Go through all loops starting from innermost.  */
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     {
       if (!loop->inner)
 	/* Unswitch innermost loop.  */
diff --git a/gcc/tree-ssa-loop.c b/gcc/tree-ssa-loop.c
index 957ac0f3baa..2255c228780 100644
--- a/gcc/tree-ssa-loop.c
+++ b/gcc/tree-ssa-loop.c
@@ -157,8 +157,7 @@ gate_oacc_kernels (function *fn)
   if (!lookup_attribute ("oacc kernels", DECL_ATTRIBUTES (fn->decl)))
     return false;
 
-  class loop *loop;
-  FOR_EACH_LOOP (loop, 0)
+  for (class loop *loop : loops_list (cfun, 0))
     if (loop->in_oacc_kernels_region)
       return true;
 
@@ -455,12 +454,11 @@ public:
 unsigned
 pass_scev_cprop::execute (function *)
 {
-  class loop *loop;
   bool any = false;
 
   /* Perform final value replacement in loops, in case the replacement
      expressions are cheap.  */
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     any |= final_value_replacement_loop (loop);
 
   return any ? TODO_cleanup_cfg | TODO_update_ssa_only_virtuals : 0;
diff --git a/gcc/tree-ssa-propagate.c b/gcc/tree-ssa-propagate.c
index d93ec90b002..1ac4d050f99 100644
--- a/gcc/tree-ssa-propagate.c
+++ b/gcc/tree-ssa-propagate.c
@@ -1262,7 +1262,6 @@ clean_up_loop_closed_phi (function *fun)
   tree rhs;
   tree lhs;
   gphi_iterator gsi;
-  struct loop *loop;
 
   /* Avoid possibly quadratic work when scanning for loop exits across
    all loops of a nest.  */
@@ -1274,7 +1273,7 @@ clean_up_loop_closed_phi (function *fun)
   calculate_dominance_info  (CDI_DOMINATORS);
 
   /* Walk over loop in function.  */
-  FOR_EACH_LOOP_FN (fun, loop, 0)
+  for (class loop *loop : loops_list (fun, 0))
     {
       /* Check each exit edege of loop.  */
       auto_vec<edge> exits = get_loop_exit_edges (loop);
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c
index 7900df946f4..1bc22950790 100644
--- a/gcc/tree-ssa-sccvn.c
+++ b/gcc/tree-ssa-sccvn.c
@@ -7637,9 +7637,8 @@ do_rpo_vn (function *fn, edge entry, bitmap exit_bbs,
      loops and the outermost one optimistically.  */
   if (iterate)
     {
-      loop_p loop;
       unsigned max_depth = param_rpo_vn_max_loop_depth;
-      FOR_EACH_LOOP (loop, LI_ONLY_INNERMOST)
+      for (class loop *loop : loops_list (cfun, LI_ONLY_INNERMOST))
 	if (loop_depth (loop) > max_depth)
 	  for (unsigned i = 2;
 	       i < loop_depth (loop) - max_depth; ++i)
diff --git a/gcc/tree-ssa-threadupdate.c b/gcc/tree-ssa-threadupdate.c
index f496dd3eb8c..ad1fd115161 100644
--- a/gcc/tree-ssa-threadupdate.c
+++ b/gcc/tree-ssa-threadupdate.c
@@ -2561,7 +2561,6 @@ jump_thread_path_registry::thread_through_all_blocks
 {
   bool retval = false;
   unsigned int i;
-  class loop *loop;
   auto_bitmap threaded_blocks;
   hash_set<edge> visited_starting_edges;
 
@@ -2702,7 +2701,7 @@ jump_thread_path_registry::thread_through_all_blocks
   /* Then perform the threading through loop headers.  We start with the
      innermost loop, so that the changes in cfg we perform won't affect
      further threading.  */
-  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
+  for (class loop *loop : loops_list (cfun, LI_FROM_INNERMOST))
     {
       if (!loop->header
 	  || !bitmap_bit_p (threaded_blocks, loop->header->index))
diff --git a/gcc/tree-vectorizer.c b/gcc/tree-vectorizer.c
index f1035a83826..ebf237d054a 100644
--- a/gcc/tree-vectorizer.c
+++ b/gcc/tree-vectorizer.c
@@ -1194,7 +1194,7 @@ vectorize_loops (void)
   /* If some loop was duplicated, it gets bigger number
      than all previously defined loops.  This fact allows us to run
      only over initial loops skipping newly generated ones.  */
-  FOR_EACH_LOOP (loop, 0)
+  for (class loop *loop : loops_list (cfun, 0))
     if (loop->dont_vectorize)
       {
 	any_ifcvt_loops = true;
@@ -1213,7 +1213,7 @@ vectorize_loops (void)
 		  loop4 (copy of loop2)
 		else
 		  loop5 (copy of loop4)
-	   If FOR_EACH_LOOP gives us loop3 first (which has
+	   If loops' iteration gives us loop3 first (which has
 	   dont_vectorize set), make sure to process loop1 before loop4;
 	   so that we can prevent vectorization of loop4 if loop1
 	   is successfully vectorized.  */
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index 0565c9b5073..abcf33c4f26 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -3337,8 +3337,7 @@ vrp_asserts::find_assert_locations (void)
   /* Pre-seed loop latch liveness from loop header PHI nodes.  Due to
      the order we compute liveness and insert asserts we otherwise
      fail to insert asserts into the loop latch.  */
-  loop_p loop;
-  FOR_EACH_LOOP (loop, 0)
+  for (class loop *loop : loops_list (cfun, 0))
     {
       i = loop->latch->index;
       unsigned int j = single_succ_edge (loop->latch)->dest_idx;