tree-optimization/114375 - disallow SLP discovery of permuted mask loads

We cannot currently handle permutations of mask loads in code generation
or permute optimization.  But we simply drop any permutation on the
floor, so the following instead rejects the SLP build rather than
producing wrong-code.  I've also made sure to reject them in
vectorizable_load for completeness.

	PR tree-optimization/114375
	* tree-vect-slp.cc (vect_build_slp_tree_2): Compute the
	load permutation for masked loads but reject it when any
	such is necessary.
	* tree-vect-stmts.cc (vectorizable_load): Reject masked
	VMAT_ELEMENTWISE and VMAT_STRIDED_SLP as those are not
	supported.

	* gcc.dg/vect/vect-pr114375.c: New testcase.

(cherry picked from commit 4f2a35a76cca503749c696e7772d2e8eadc77ba5)

diff --git a/gcc/testsuite/gcc.dg/vect/vect-pr114375.c b/gcc/testsuite/gcc.dg/vect/vect-pr114375.c
new file mode 100644 (file)
index 0000000..1e1cb01
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-pr114375.c
@@ -0,0 +1,44 @@
+/* { dg-additional-options "-mavx2" { target avx2_runtime } } */
+
+#include "tree-vect.h"
+
+int a[512];
+int b[512];
+int c[512];
+
+void __attribute__((noipa))
+foo(int * __restrict p)
+{
+  for (int i = 0; i < 64; ++i)
+    {
+      int tem = 2, tem2 = 2;
+      if (a[4*i + 1])
+        tem = p[4*i];
+      if (a[4*i])
+        tem2 = p[4*i + 2];
+      b[2*i] = tem2;
+      b[2*i+1] = tem;
+      if (a[4*i + 2])
+        tem = p[4*i + 1];
+      if (a[4*i + 3])
+        tem2 = p[4*i + 3];
+      c[2*i] = tem2;
+      c[2*i+1] = tem;
+    }
+}
+int main()
+{
+  check_vect ();
+
+  for (int i = 0; i < 512; ++i)
+    a[i] = (i >> 1) & 1;
+
+  foo (a);
+
+  if (c[0] != 1 || c[1] != 0 || c[2] != 1 || c[3] != 0
+      || b[0] != 2 || b[1] != 2 || b[2] != 2 || b[3] != 2)
+    abort ();
+
+  return 0;
+}
+

diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
index f33e85337abd550e43bde845cade5cbc7f99e26a..26c989cbff9ac6ba702acbca12789fb2e4ee9954 100644 (file)
--- a/gcc/tree-vect-slp.cc
+++ b/gcc/tree-vect-slp.cc
@@ -1722,10 +1722,8 @@ vect_build_slp_tree_2 (vec_info *vinfo, slp_tree node,
   if (STMT_VINFO_GROUPED_ACCESS (stmt_info)
       && DR_IS_READ (STMT_VINFO_DATA_REF (stmt_info)))
     {
-      if (gcall *stmt = dyn_cast <gcall *> (stmt_info->stmt))
-       gcc_assert (gimple_call_internal_p (stmt, IFN_MASK_LOAD)
-                   || gimple_call_internal_p (stmt, IFN_GATHER_LOAD)
-                   || gimple_call_internal_p (stmt, IFN_MASK_GATHER_LOAD));
+      if (STMT_VINFO_GATHER_SCATTER_P (stmt_info))
+       gcc_assert (DR_IS_READ (STMT_VINFO_DATA_REF (stmt_info)));
       else
        {
          *max_nunits = this_max_nunits;
@@ -1741,15 +1739,37 @@ vect_build_slp_tree_2 (vec_info *vinfo, slp_tree node,
          load_permutation.create (group_size);
          stmt_vec_info first_stmt_info
            = DR_GROUP_FIRST_ELEMENT (SLP_TREE_SCALAR_STMTS (node)[0]);
+         bool any_permute = false;
          FOR_EACH_VEC_ELT (SLP_TREE_SCALAR_STMTS (node), j, load_info)
            {
              int load_place = vect_get_place_in_interleaving_chain
                  (load_info, first_stmt_info);
              gcc_assert (load_place != -1);
-             load_permutation.safe_push (load_place);
+             any_permute |= load_place != j;
+             load_permutation.quick_push (load_place);
+           }
+
+         if (gcall *stmt = dyn_cast <gcall *> (stmt_info->stmt))
+           {
+             gcc_assert (gimple_call_internal_p (stmt, IFN_MASK_LOAD)
+                         || gimple_call_internal_p (stmt, IFN_GATHER_LOAD)
+                         || gimple_call_internal_p (stmt, IFN_MASK_GATHER_LOAD));
+             load_permutation.release ();
+             /* We cannot handle permuted masked loads, see PR114375.  */
+             if (any_permute
+                 || (STMT_VINFO_GROUPED_ACCESS (stmt_info)
+                     && DR_GROUP_SIZE (first_stmt_info) != group_size)
+                 || STMT_VINFO_STRIDED_P (stmt_info))
+               {
+                 matches[0] = false;
+                 return NULL;
+               }
+           }
+         else
+           {
+             SLP_TREE_LOAD_PERMUTATION (node) = load_permutation;
+             return node;
            }
-         SLP_TREE_LOAD_PERMUTATION (node) = load_permutation;
-         return node;
        }
     }
   else if (gimple_assign_single_p (stmt_info->stmt)

diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index 34920041116bba750efaffcf5ee839db99bdd6ae..b1ab4bce7d28a8c04ec8d6512eac5f63beddb35f 100644 (file)
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -8994,6 +8994,14 @@ vectorizable_load (vec_info *vinfo,
                             "unsupported masked emulated gather.\n");
          return false;
        }
+      else if (memory_access_type == VMAT_ELEMENTWISE
+              || memory_access_type == VMAT_STRIDED_SLP)
+       {
+         if (dump_enabled_p ())
+           dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+                            "unsupported masked strided access.\n");
+         return false;
+       }
     }
 
   if (!vec_stmt) /* transformation not required.  */