tree-vect-loop.c (vect_analyze_loop_2): Check and skip loop if it has no enough…

tree-vect-loop.c (vect_analyze_loop_2): Check and skip loop if it has no enough iterations for LOOP_VINFO_PEELING_FOR_GAPS.

	* tree-vect-loop.c (vect_analyze_loop_2): Check and skip loop if it
	has no enough iterations for LOOP_VINFO_PEELING_FOR_GAPS.

	gcc/testsuite
	* gcc.dg/vect/vect-98.c: Refine test case.
	* gcc.dg/vect/vect-strided-a-u8-i8-gap2.c: Increase niters.
	* gcc.dg/vect/vect-strided-u8-i8-gap2.c: Ditto.
	* gcc.dg/vect/vect-strided-u8-i8-gap4.c: Ditto.

From-SVN: r241097

gcc/ChangeLog

 2016-10-13  Bin Cheng  <bin.cheng@arm.com>
 
+	* tree-vect-loop.c (vect_analyze_loop_2): Check and skip loop if it
+	has no enough iterations for LOOP_VINFO_PEELING_FOR_GAPS.
+
+2016-10-13  Bin Cheng  <bin.cheng@arm.com>
+
 	* tree-vect-loop.c (vectorizable_live_operation): Support handling
 	for live variable outside loop but not in lcssa form.
 

gcc/testsuite/ChangeLog

+2016-10-13  Bin Cheng  <bin.cheng@arm.com>
+
+	* gcc.dg/vect/vect-98.c: Refine test case.
+	* gcc.dg/vect/vect-strided-a-u8-i8-gap2.c: Increase niters.
+	* gcc.dg/vect/vect-strided-u8-i8-gap2.c: Ditto.
+	* gcc.dg/vect/vect-strided-u8-i8-gap4.c: Ditto.
+
 2016-10-13  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c/77946

gcc/testsuite/gcc.dg/vect/vect-98.c

@@ -3,6 +3,7 @@
 #include <stdarg.h>
 #include "tree-vect.h"
 
+#define M 8
 #define N 4
 #define DOT4( a, b )  ( a[0]*b[0] + a[1]*b[1] + a[2]*b[2] + a[3]*b[3] )
 
@@ -11,15 +12,15 @@ int main1 (int ia[][N])
 {
   int i, j;
   int ib[N] = {0,3,6,9};
-  int ic[N][N];
+  int ic[M][M];
 
-  for (i = 0; i < N; i++)
+  for (i = 0; i < M; i++)
     {
 	ic[0][i] = DOT4 (ia[i], ib);
     }
 
   /* check results: */  
-  for (i = 0; i < N; i++)
+  for (i = 0; i < M; i++)
     {
        if (ic[0][i] != DOT4 (ia[i], ib))
            abort();
@@ -30,7 +31,8 @@ int main1 (int ia[][N])
 
 int main (void)
 { 
-  int ia[N][N] = {{1,2,3,4},{2,3,5,7},{2,4,6,8},{22,43,55,77}};
+  int ia[M][N] = {{1,2,3,4},{2,3,5,7},{2,4,6,8},{22,43,55,77},
+		  {13,17,19,23},{29,31,37,41},{3,7,2,1},{4,9,8,3}};
 
   check_vect ();
 

gcc/testsuite/gcc.dg/vect/vect-strided-a-u8-i8-gap2.c

@@ -3,7 +3,7 @@
 #include <stdarg.h>
 #include "tree-vect.h"
 
-#define N 16 
+#define N 24
 
 typedef struct {
    unsigned char a;

gcc/testsuite/gcc.dg/vect/vect-strided-u8-i8-gap2.c

@@ -3,7 +3,7 @@
 #include <stdarg.h>
 #include "tree-vect.h"
 
-#define N 16 
+#define N 24
 
 typedef struct {
    unsigned char a;

gcc/testsuite/gcc.dg/vect/vect-strided-u8-i8-gap4.c

@@ -3,7 +3,7 @@
 #include <stdarg.h>
 #include "tree-vect.h"
 
-#define N 16 
+#define N 24
 
 typedef struct {
    unsigned char a;

gcc/tree-vect-loop.c

@@ -2059,6 +2059,25 @@ start_over:
       return false;
     }
 
+  /* If epilog loop is required because of data accesses with gaps,
+     one additional iteration needs to be peeled.  Check if there is
+     enough iterations for vectorization.  */
+  if (LOOP_VINFO_PEELING_FOR_GAPS (loop_vinfo)
+      && LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo))
+    {
+      int vf = LOOP_VINFO_VECT_FACTOR (loop_vinfo);
+      tree scalar_niters = LOOP_VINFO_NITERSM1 (loop_vinfo);
+
+      if (wi::to_widest (scalar_niters) < vf)
+	{
+	  if (dump_enabled_p ())
+	    dump_printf_loc (MSG_NOTE, vect_location,
+			     "loop has no enough iterations to support"
+			     " peeling for gaps.\n");
+	  return false;
+	}
+    }
+
   /* Analyze cost.  Decide if worth while to vectorize.  */
   int min_profitable_estimate, min_profitable_iters;
   vect_estimate_min_profitable_iters (loop_vinfo, &min_profitable_iters,