[gcc(refs/users/guojiufu/heads/guojiufu-branch)] refine loop unroll heuristic.

[gcc(refs/users/guojiufu/heads/guojiufu-branch)] refine loop unroll heuristic.

[Jiu Fu Guo]

https://gcc.gnu.org/g:8df3e68e22700ab4f24c42d1b05079e889a5da5b

commit 8df3e68e22700ab4f24c42d1b05079e889a5da5b
Author: guojiufu <guojiufu@linux.ibm.com>
Date:   Mon Jun 29 12:50:11 2020 +0800

    refine loop unroll heuristic.

Diff:
---
 gcc/config/rs6000/rs6000.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index d62e413670a..1c5e76953ac 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -5130,11 +5130,33 @@ rs6000_destroy_cost_data (void *data)
   free (data);
 }
 
+/* Count call insns in a loop.  */
+static unsigned int
+count_call_in_loop (struct loop *loop)
+{
+  basic_block *bbs;
+  rtx_insn *insn;
+  unsigned int i;
+  unsigned int call_ins_num = 0;
+
+  bbs = get_loop_body (loop);
+  for (i = 0; i < loop->num_nodes; i++)
+    FOR_BB_INSNS (bbs[i], insn)
+      if (CALL_P (insn))
+	call_ins_num++;
+
+  free (bbs);
+
+  return call_ins_num;
+}
+
 /* Implement targetm.loop_unroll_adjust.  */
 
 static unsigned
 rs6000_loop_unroll_adjust (unsigned nunroll, struct loop *loop)
 {
+  unsigned call_num;
+
   if (unroll_only_small_loops)
     {
       /* TODO: Hardcoded here, PARAM may be used for this.  */
@@ -5142,9 +5164,17 @@ rs6000_loop_unroll_adjust (unsigned nunroll, struct loop *loop)
 	return MIN (4, nunroll);
       if (loop->ninsns <= 10)
 	return MIN (2, nunroll);
+
       return 0;
     }
 
+  /* Do not unroll very complex loop.  */
+  if (loop->ninsns > 10
+      && (call_num = count_call_in_loop (loop)) > 0
+      && (call_num + num_loop_branches (loop)) * 5 > loop->ninsns
+      && !single_exit (loop))
+    return 0;
+
   return nunroll;
 }