Use vec_perm_builder::series_p in shift_amt_for_vec_perm_mask

This patch makes shift_amt_for_vec_perm_mask use series_p to check
for the simple case of a natural linear series before falling back
to testing each element individually.  The series_p test works with
variable-length vectors but testing every individual element doesn't.

2018-01-02  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
	* optabs.c (shift_amt_for_vec_perm_mask): Try using series_p
	before testing each element individually.
	* tree-vect-generic.c (lower_vec_perm): Likewise.

From-SVN: r256099

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9e3face038b38f382527ebfb43d1eed989429ac1..1dfb6839d10bbc050faf9dd26c4f93b2959a071a 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2018-01-02  Richard Sandiford  <richard.sandiford@linaro.org>
+
+       * optabs.c (shift_amt_for_vec_perm_mask): Try using series_p
+       before testing each element individually.
+       * tree-vect-generic.c (lower_vec_perm): Likewise.
+
 2018-01-02  Richard Sandiford  <richard.sandiford@linaro.org>
 
        * selftest.h (selftest::vec_perm_indices_c_tests): Declare.

diff --git a/gcc/optabs.c b/gcc/optabs.c
index e9ce42fb9eefed64307792ec2d52d5e73d921877..dcd94cd5a301b783720353d2f21b39db14a9c624 100644 (file)
--- a/gcc/optabs.c
+++ b/gcc/optabs.c
@@ -5395,20 +5395,20 @@ vector_compare_rtx (machine_mode cmp_mode, enum tree_code tcode,
 static rtx
 shift_amt_for_vec_perm_mask (machine_mode mode, const vec_perm_indices &sel)
 {
-  unsigned int i, first, nelt = GET_MODE_NUNITS (mode);
+  unsigned int nelt = GET_MODE_NUNITS (mode);
   unsigned int bitsize = GET_MODE_UNIT_BITSIZE (mode);
-
-  first = sel[0];
+  unsigned int first = sel[0];
   if (first >= nelt)
     return NULL_RTX;
-  for (i = 1; i < nelt; i++)
-    {
-      int idx = sel[i];
-      unsigned int expected = i + first;
-      /* Indices into the second vector are all equivalent.  */
-      if (idx < 0 || (MIN (nelt, (unsigned) idx) != MIN (nelt, expected)))
-       return NULL_RTX;
-    }
+
+  if (!sel.series_p (0, 1, first, 1))
+    for (unsigned int i = 1; i < nelt; i++)
+      {
+       unsigned int expected = i + first;
+       /* Indices into the second vector are all equivalent.  */
+       if (MIN (nelt, sel[i]) != MIN (nelt, expected))
+         return NULL_RTX;
+      }
 
   return gen_int_shift_amount (mode, first * bitsize);
 }

diff --git a/gcc/tree-vect-generic.c b/gcc/tree-vect-generic.c
index 767721cd62ca0406d1f111b2b9b84f4c8a2058eb..602cea3775541ac889f6ba0fdb05dfe911216f4b 100644 (file)
--- a/gcc/tree-vect-generic.c
+++ b/gcc/tree-vect-generic.c
@@ -1320,15 +1320,20 @@ lower_vec_perm (gimple_stmt_iterator *gsi)
          && indices[0]
          && indices[0] < elements)
        {
-         for (i = 1; i < elements; ++i)
+         bool ok_p = indices.series_p (0, 1, indices[0], 1);
+         if (!ok_p)
            {
-             unsigned int expected = i + indices[0];
-             /* Indices into the second vector are all equivalent.  */
-             if (MIN (elements, (unsigned) indices[i])
-                 != MIN (elements, expected))
-               break;
+             for (i = 1; i < elements; ++i)
+               {
+                 unsigned int expected = i + indices[0];
+                 /* Indices into the second vector are all equivalent.  */
+                 if (MIN (elements, (unsigned) indices[i])
+                     != MIN (elements, expected))
+                   break;
+               }
+             ok_p = i == elements;
            }
-         if (i == elements)
+         if (ok_p)
            {
              gimple_assign_set_rhs3 (stmt, mask);
              update_stmt (stmt);