[PATCH GCC8][25/33]New loop constraint flags

[Bin Cheng]

Hi,
This patch adds new loop constraint flags marking prologue, epilogue and 
versioned loops generated
by vectorizer, unroller and versioning.  These flags will be used in IVOPTs in 
order to differentiate
possible hot innermost loop from others.  I also plan to use them to avoid 
unnecessary cunroll on
such loops.
Is it OK?

Thanks,
bin
2017-04-11  Bin Cheng  <bin.ch...@arm.com>

        * cfgloop.h (LOOP_C_PROLOG, LOOP_C_EPILOG, LOOP_C_VERSION): New.
        * tree-ssa-loop-manip.c (tree_transform_and_unroll_loop): Set
        LOOP_C_EPILOG for unrolled epilogue loop.
        (vect_do_peeling): Set LOOP_C_PROLOG and LOOP_C_EPILOG for peeled
        loops.
        (vect_loop_versioning): Set LOOP_C_VERSION for versioned loop.
From 432006f72b95826eadb4c972a55b1aeb89c9998b Mon Sep 17 00:00:00 2001
From: Bin Cheng <binch...@e108451-lin.cambridge.arm.com>
Date: Thu, 30 Mar 2017 10:56:19 +0100
Subject: [PATCH 25/33] new-loop-constraint-flags-20170310.txt

---
 gcc/cfgloop.h              | 6 ++++++
 gcc/tree-ssa-loop-manip.c  | 1 +
 gcc/tree-vect-loop-manip.c | 3 +++
 3 files changed, 10 insertions(+)

diff --git a/gcc/cfgloop.h b/gcc/cfgloop.h
index a8bec1d..90be4cc 100644
--- a/gcc/cfgloop.h
+++ b/gcc/cfgloop.h
@@ -248,6 +248,12 @@ struct GTY ((chain_next ("%h.next"))) loop {
 #define LOOP_C_INFINITE                (1 << 0)
 /* Set if the loop is known to be finite without any assumptions.  */
 #define LOOP_C_FINITE          (1 << 1)
+/* Set if the loop is peeled prologue loop.  */
+#define LOOP_C_PROLOG          (1 << 2)
+/* Set if the loop is peeled epilogue loop.  */
+#define LOOP_C_EPILOG          (1 << 3)
+/* Set if the loop is versioned loop.  */
+#define LOOP_C_VERSION         (1 << 4)
 
 /* Set C to the LOOP constraint.  */
 static inline void
diff --git a/gcc/tree-ssa-loop-manip.c b/gcc/tree-ssa-loop-manip.c
index 22c832a..0559904 100644
--- a/gcc/tree-ssa-loop-manip.c
+++ b/gcc/tree-ssa-loop-manip.c
@@ -1233,6 +1233,7 @@ tree_transform_and_unroll_loop (struct loop *loop, 
unsigned factor,
                           scale_unrolled, scale_rest, true);
   gcc_assert (new_loop != NULL);
   update_ssa (TODO_update_ssa);
+  loop_constraint_set (new_loop, LOOP_C_EPILOG);
 
   /* Prepare the cfg and update the phi nodes.  Move the loop exit to the
      loop latch (and make its condition dummy, for the moment).  */
diff --git a/gcc/tree-vect-loop-manip.c b/gcc/tree-vect-loop-manip.c
index f48336b..faeaa6d 100644
--- a/gcc/tree-vect-loop-manip.c
+++ b/gcc/tree-vect-loop-manip.c
@@ -1735,6 +1735,7 @@ vect_do_peeling (loop_vec_info loop_vinfo, tree niters, 
tree nitersm1,
          gcc_unreachable ();
        }
       slpeel_update_phi_nodes_for_loops (loop_vinfo, prolog, loop, true);
+      loop_constraint_set (prolog, LOOP_C_PROLOG);
       first_loop = prolog;
       reset_original_copy_tables ();
 
@@ -1799,6 +1800,7 @@ vect_do_peeling (loop_vec_info loop_vinfo, tree niters, 
tree nitersm1,
          gcc_unreachable ();
        }
       slpeel_update_phi_nodes_for_loops (loop_vinfo, loop, epilog, false);
+      loop_constraint_set (epilog, LOOP_C_EPILOG);
 
       /* Scalar version loop may be preferred.  In this case, add guard
         and skip to epilog.  Note this only happens when the number of
@@ -2400,6 +2402,7 @@ vect_loop_versioning (loop_vec_info loop_vinfo,
                          prob, REG_BR_PROB_BASE - prob,
                          prob, REG_BR_PROB_BASE - prob, true);
 
+  loop_constraint_set (nloop, LOOP_C_VERSION);
   if (version_niter)
     {
       /* The versioned loop could be infinite, we need to clear existing
-- 
1.9.1