re PR tree-optimization/68892 (Excessive dead loads produced by BB vectorization)

2015-12-16  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/68892
	* tree-vect-slp.c (vect_analyze_slp_cost_1): Properly compute
	cost for permuted loads.

	* gcc.dg/vect/bb-slp-pr68892.c: New testcase.

From-SVN: r231674

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c68fd132e34b5de5a39edba0ebef523b7142423b..6450d52b0c2c1688dd230f7e987fbd9e7027eb5b 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2015-12-16  Richard Biener  <rguenther@suse.de>
+
+       PR tree-optimization/68892
+       * tree-vect-slp.c (vect_analyze_slp_cost_1): Properly compute
+       cost for permuted loads.
+
 2015-12-16  Jakub Jelinek  <jakub@redhat.com>
 
        PR rtl-optimization/65980

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index a0b8fda8b3c74aa0e558b6e2e5d2d6fad745530d..7a3c5e469957494a18f732b8bda4d4e039798f61 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2015-12-16  Richard Biener  <rguenther@suse.de>
+
+       PR tree-optimization/68892
+       * gcc.dg/vect/bb-slp-pr68892.c: New testcase.
+
 2015-12-16  Jakub Jelinek  <jakub@redhat.com>
 
        PR rtl-optimization/65980

diff --git a/gcc/testsuite/gcc.dg/vect/bb-slp-pr68892.c b/gcc/testsuite/gcc.dg/vect/bb-slp-pr68892.c
new file mode 100644 (file)
index 0000000..648fe48
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/bb-slp-pr68892.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-fvect-cost-model=dynamic" } */
+
+double a[128][128];
+double b[128];
+
+void foo(void)
+{
+  b[0] = a[0][0];
+  b[1] = a[1][0];
+  b[2] = a[2][0];
+  b[3] = a[3][0];
+}
+
+/* { dg-final { scan-tree-dump "not profitable" "slp2" } } */
+/* { dg-final { scan-tree-dump-times "Basic block will be vectorized" 0 "slp2" } } */

diff --git a/gcc/tree-vect-slp.c b/gcc/tree-vect-slp.c
index 3fdc988b4d6693d9dcd010bf51b00687c810deed..f57c859cd4ad1cc7008acb3b31520e9fb7256d4d 100644 (file)
--- a/gcc/tree-vect-slp.c
+++ b/gcc/tree-vect-slp.c
@@ -1402,10 +1402,9 @@ vect_analyze_slp_cost_1 (slp_instance instance, slp_tree node,
 {
   unsigned i, j;
   slp_tree child;
-  gimple *stmt, *s;
+  gimple *stmt;
   stmt_vec_info stmt_info;
   tree lhs;
-  unsigned group_size = SLP_INSTANCE_GROUP_SIZE (instance);
 
   /* Recurse down the SLP tree.  */
   FOR_EACH_VEC_ELT (SLP_TREE_CHILDREN (node), i, child)
@@ -1424,44 +1423,39 @@ vect_analyze_slp_cost_1 (slp_instance instance, slp_tree node,
                               node, prologue_cost_vec, body_cost_vec);
       else
        {
-         int i;
          gcc_checking_assert (DR_IS_READ (STMT_VINFO_DATA_REF (stmt_info)));
-         /* If the load is permuted then the alignment is determined by
-            the first group element not by the first scalar stmt DR.  */
          if (SLP_TREE_LOAD_PERMUTATION (node).exists ())
            {
+             /* If the load is permuted then the alignment is determined by
+                the first group element not by the first scalar stmt DR.  */
              stmt = GROUP_FIRST_ELEMENT (stmt_info);
              stmt_info = vinfo_for_stmt (stmt);
+             /* Record the cost for the permutation.  */
+             record_stmt_cost (body_cost_vec, ncopies_for_cost, vec_perm,
+                               stmt_info, 0, vect_body);
+             /* And adjust the number of loads performed.  */
+             unsigned nunits
+               = TYPE_VECTOR_SUBPARTS (STMT_VINFO_VECTYPE (stmt_info));
+             ncopies_for_cost
+               = (GROUP_SIZE (stmt_info) - GROUP_GAP (stmt_info)
+                  + nunits - 1) / nunits;
+             ncopies_for_cost *= SLP_INSTANCE_UNROLLING_FACTOR (instance);
            }
+         /* Record the cost for the vector loads.  */
          vect_model_load_cost (stmt_info, ncopies_for_cost, false,
                                node, prologue_cost_vec, body_cost_vec);
-         /* If the load is permuted record the cost for the permutation.
-            ???  Loads from multiple chains are let through here only
-            for a single special case involving complex numbers where
-            in the end no permutation is necessary.  */
-         FOR_EACH_VEC_ELT (SLP_TREE_SCALAR_STMTS (node), i, s)
-           if ((STMT_VINFO_GROUP_FIRST_ELEMENT (vinfo_for_stmt (s))
-                == STMT_VINFO_GROUP_FIRST_ELEMENT (stmt_info))
-               && vect_get_place_in_interleaving_chain
-                    (s, STMT_VINFO_GROUP_FIRST_ELEMENT (stmt_info)) != i)
-             {
-               record_stmt_cost (body_cost_vec, group_size, vec_perm,
-                                 stmt_info, 0, vect_body);
-               break;
-             }
        }
+      return;
     }
-  else
+
+  record_stmt_cost (body_cost_vec, ncopies_for_cost, vector_stmt,
+                   stmt_info, 0, vect_body);
+  if (SLP_TREE_TWO_OPERATORS (node))
     {
       record_stmt_cost (body_cost_vec, ncopies_for_cost, vector_stmt,
                        stmt_info, 0, vect_body);
-      if (SLP_TREE_TWO_OPERATORS (node))
-       {
-         record_stmt_cost (body_cost_vec, ncopies_for_cost, vector_stmt,
-                           stmt_info, 0, vect_body);
-         record_stmt_cost (body_cost_vec, ncopies_for_cost, vec_perm,
-                           stmt_info, 0, vect_body);
-       }
+      record_stmt_cost (body_cost_vec, ncopies_for_cost, vec_perm,
+                       stmt_info, 0, vect_body);
     }
 
   /* Push SLP node def-type to stmts.  */