[vect]Account for epilogue's peeling for gaps when checking if we have enough

niters for epilogue

gcc/ChangeLog:
2019-11-11  Andre Vieira  <andre.simoesdiasvieira@arm.com>

	* tree-vect-loop-manip.c (vect_do_peeling): Take epilogue gaps into
	account when checking if there are enough iterations to vectorize
	epilogue.

gcc/testsuite/ChangeLog:
2019-11-11  Andre Vieira  <andre.simoesdiasvieira@arm.com>

	* gcc.dg/vect/vect-reduc-epilogue-gaps.c: New test.

From-SVN: r278049

gcc/ChangeLog

+2019-11-11  Andre Vieira  <andre.simoesdiasvieira@arm.com>
+
+	* tree-vect-loop-manip.c (vect_do_peeling): Take epilogue gaps into
+	account when checking if there are enough iterations to vectorize
+	epilogue.
+
 2019-11-11  Tobias Burnus  <tobias@codesourcery.com>
 	    Kwok Cheung Yeung  <kcy@codesourcery.com>
 

gcc/testsuite/ChangeLog

+2019-11-11  Andre Vieira  <andre.simoesdiasvieira@arm.com>
+
+	* gcc.dg/vect/vect-reduc-epilogue-gaps.c: New test.
+
 2019-11-11  José Rui Faustino de Sousa  <jrfsousa@gmail.com>
 
 	PR fortran/92142

gcc/testsuite/gcc.dg/vect/vect-reduc-epilogue-gaps.c

+/* { dg-options "-O3 -fno-vect-cost-model" } */
+struct {
+    float real;
+    float img;
+} g[11];
+
+float __attribute__ ((noclone))
+foo_11 (void)
+{
+  float sum = 0.0;
+  for (int i = 0; i < 11; ++i)
+    sum += g[i].real;
+  return sum;
+}
+
+float __attribute__ ((noclone))
+foo_10 (void)
+{
+  float sum = 0.0;
+  for (int i = 0; i < 10; ++i)
+    sum += g[i].real;
+  return sum;
+}
+
+int main (void)
+{
+  float check_10 = 0.0;
+  float check_11 = 0.0;
+  for (int i = 0; i < 11; ++i)
+    {
+      asm volatile ("" : : : "memory");
+      g[i].real = (float) i;
+      g[i].img = (float) -i;
+      if (i < 10)
+	check_10 += (float) i;
+      check_11 += (float) i;
+    }
+
+  if (foo_10 () != check_10)
+    __builtin_abort ();
+  if (foo_11 () != check_11)
+    __builtin_abort ();
+
+  return 0;
+}

gcc/tree-vect-loop-manip.c

@@ -2530,9 +2530,11 @@ vect_do_peeling (loop_vec_info loop_vinfo, tree niters, tree nitersm1,
 	= eiters % lowest_vf + LOOP_VINFO_PEELING_FOR_GAPS (loop_vinfo);
 
       unsigned int ratio;
+      unsigned int epilogue_gaps
+	= LOOP_VINFO_PEELING_FOR_GAPS (epilogue_vinfo);
       while (!(constant_multiple_p (loop_vinfo->vector_size,
 				    epilogue_vinfo->vector_size, &ratio)
-	       && eiters >= lowest_vf / ratio))
+	       && eiters >= lowest_vf / ratio + epilogue_gaps))
 	{
 	  delete epilogue_vinfo;
 	  epilogue_vinfo = NULL;
@@ -2543,6 +2545,7 @@ vect_do_peeling (loop_vec_info loop_vinfo, tree niters, tree nitersm1,
 	    }
 	  epilogue_vinfo = loop_vinfo->epilogue_vinfos[0];
 	  loop_vinfo->epilogue_vinfos.ordered_remove (0);
+	  epilogue_gaps = LOOP_VINFO_PEELING_FOR_GAPS (epilogue_vinfo);
 	}
     }
   /* Prolog loop may be skipped.  */