tree-optimization/102139 - fix SLP DR base alignment

When doing whole-function SLP we have to make sure the recorded
base alignments we compute as the maximum alignment seen for a
base anywhere in the function is actually valid at the point
we want to make use of it.

To make this work we now record the stmt the alignment was derived
from in addition to the DRs innermost behavior and we use a
dominance check to verify the recorded info is valid when doing
BB vectorization.  For this to work for groups inside a BB that are
separate by a call that might not return we now store the DR
analysis group-id permanently and use that for an additional check
when the DRs are in the same BB.

2021-08-31  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/102139
	* tree-vectorizer.h (vec_base_alignments): Adjust hash-map
	type to record a std::pair of the stmt-info and the innermost
	loop behavior.
	(dr_vec_info::group): New member.
	* tree-vect-data-refs.c (vect_record_base_alignment): Adjust.
	(vect_compute_data_ref_alignment): Verify the recorded
	base alignment can be used.
	(data_ref_pair): Remove.
	(dr_group_sort_cmp): Adjust.
	(vect_analyze_data_ref_accesses): Store the group-ID in the
	dr_vec_info and operate on a vector of dr_vec_infos.

	* gcc.dg/torture/pr102139.c: New testcase.

(cherry picked from commit 153766ec8351d55cfe8bd6d69bdfc0c2cef71e56)

diff --git a/gcc/testsuite/gcc.dg/torture/pr102139.c b/gcc/testsuite/gcc.dg/torture/pr102139.c
new file mode 100644 (file)
index 0000000..06c1357
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr102139.c
@@ -0,0 +1,43 @@
+/* { dg-do run } */
+/* { dg-additional-options "-ftree-slp-vectorize" } */
+
+typedef double aligned_double __attribute__((aligned(2*sizeof(double))));
+
+void __attribute__((noipa))
+bar (int aligned, double *p)
+{
+  if (aligned)
+    {
+      *(aligned_double *)p = 3.;
+      p[1] = 4.;
+    }
+  else
+    {
+      p[2] = 0.;
+      p[3] = 1.;
+    }
+}
+
+void __attribute__((noipa))
+foo (int i)
+{
+  if (i)
+    __builtin_exit (0);
+}
+void __attribute__((noipa))
+baz (double *p)
+{
+  p[0] = 0.;
+  p[1] = 1.;
+  foo (1);
+  *(aligned_double *)p = 3.;
+  p[1] = 4.;
+}
+
+double x[8] __attribute__((aligned(2*sizeof (double))));
+int main()
+{
+  bar (0, &x[1]);
+  baz (&x[1]);
+  return 0;
+}

diff --git a/gcc/tree-vect-data-refs.c b/gcc/tree-vect-data-refs.c
index 4fa6e156204271e644eca1eab777e06ec307893f..23f4a7ef15f85ded76fe11b1884b4422761f6c54 100644 (file)
--- a/gcc/tree-vect-data-refs.c
+++ b/gcc/tree-vect-data-refs.c
@@ -892,11 +892,11 @@ vect_record_base_alignment (vec_info *vinfo, stmt_vec_info stmt_info,
                            innermost_loop_behavior *drb)
 {
   bool existed;
-  innermost_loop_behavior *&entry
+  std::pair<stmt_vec_info, innermost_loop_behavior *> &entry
     = vinfo->base_alignments.get_or_insert (drb->base_address, &existed);
-  if (!existed || entry->base_alignment < drb->base_alignment)
+  if (!existed || entry.second->base_alignment < drb->base_alignment)
     {
-      entry = drb;
+      entry = std::make_pair (stmt_info, drb);
       if (dump_enabled_p ())
        dump_printf_loc (MSG_NOTE, vect_location,
                         "recording new base alignment for %T\n"
@@ -1059,11 +1059,18 @@ vect_compute_data_ref_alignment (vec_info *vinfo, dr_vec_info *dr_info)
 
   /* Calculate the maximum of the pooled base address alignment and the
      alignment that we can compute for DR itself.  */
-  innermost_loop_behavior **entry = base_alignments->get (drb->base_address);
-  if (entry && base_alignment < (*entry)->base_alignment)
+  std::pair<stmt_vec_info, innermost_loop_behavior *> *entry
+    = base_alignments->get (drb->base_address);
+  if (entry
+      && base_alignment < (*entry).second->base_alignment
+      && (loop_vinfo
+         || (dominated_by_p (CDI_DOMINATORS, gimple_bb (stmt_info->stmt),
+                             gimple_bb (entry->first->stmt))
+             && (gimple_bb (stmt_info->stmt) != gimple_bb (entry->first->stmt)
+                 || (entry->first->dr_aux.group <= dr_info->group)))))
     {
-      base_alignment = (*entry)->base_alignment;
-      base_misalignment = (*entry)->base_misalignment;
+      base_alignment = entry->second->base_alignment;
+      base_misalignment = entry->second->base_misalignment;
     }
 
   if (drb->offset_alignment < vect_align_c
@@ -2817,18 +2824,16 @@ vect_analyze_data_ref_access (vec_info *vinfo, dr_vec_info *dr_info)
   return vect_analyze_group_access (vinfo, dr_info);
 }
 
-typedef std::pair<data_reference_p, int> data_ref_pair;
-
 /* Compare two data-references DRA and DRB to group them into chunks
    suitable for grouping.  */
 
 static int
 dr_group_sort_cmp (const void *dra_, const void *drb_)
 {
-  data_ref_pair dra_pair = *(data_ref_pair *)const_cast<void *>(dra_);
-  data_ref_pair drb_pair = *(data_ref_pair *)const_cast<void *>(drb_);
-  data_reference_p dra = dra_pair.first;
-  data_reference_p drb = drb_pair.first;
+  dr_vec_info *dra_info = *(dr_vec_info **)const_cast<void *>(dra_);
+  dr_vec_info *drb_info = *(dr_vec_info **)const_cast<void *>(drb_);
+  data_reference_p dra = dra_info->dr;
+  data_reference_p drb = drb_info->dr;
   int cmp;
 
   /* Stabilize sort.  */
@@ -2836,8 +2841,8 @@ dr_group_sort_cmp (const void *dra_, const void *drb_)
     return 0;
 
   /* Different group IDs lead never belong to the same group.  */
-  if (dra_pair.second != drb_pair.second)
-    return dra_pair.second < drb_pair.second ? -1 : 1;
+  if (dra_info->group != drb_info->group)
+    return dra_info->group < drb_info->group ? -1 : 1;
 
   /* Ordering of DRs according to base.  */
   cmp = data_ref_compare_tree (DR_BASE_ADDRESS (dra),
@@ -2957,18 +2962,18 @@ vect_analyze_data_ref_accesses (vec_info *vinfo,
   /* Sort the array of datarefs to make building the interleaving chains
      linear.  Don't modify the original vector's order, it is needed for
      determining what dependencies are reversed.  */
-  vec<data_ref_pair> datarefs_copy;
+  vec<dr_vec_info *> datarefs_copy;
   datarefs_copy.create (datarefs.length ());
   for (unsigned i = 0; i < datarefs.length (); i++)
     {
-      int group_id;
+      dr_vec_info *dr_info = vinfo->lookup_dr (datarefs[i]);
       /* If the caller computed DR grouping use that, otherwise group by
         basic blocks.  */
       if (dataref_groups)
-       group_id = (*dataref_groups)[i];
+       dr_info->group = (*dataref_groups)[i];
       else
-       group_id = gimple_bb (DR_STMT (datarefs[i]))->index;
-      datarefs_copy.quick_push (data_ref_pair (datarefs[i], group_id));
+       dr_info->group = gimple_bb (DR_STMT (datarefs[i]))->index;
+      datarefs_copy.quick_push (dr_info);
     }
   datarefs_copy.qsort (dr_group_sort_cmp);
   hash_set<stmt_vec_info> to_fixup;
@@ -2976,9 +2981,9 @@ vect_analyze_data_ref_accesses (vec_info *vinfo,
   /* Build the interleaving chains.  */
   for (i = 0; i < datarefs_copy.length () - 1;)
     {
-      data_reference_p dra = datarefs_copy[i].first;
-      int dra_group_id = datarefs_copy[i].second;
-      dr_vec_info *dr_info_a = vinfo->lookup_dr (dra);
+      dr_vec_info *dr_info_a = datarefs_copy[i];
+      data_reference_p dra = dr_info_a->dr;
+      int dra_group_id = dr_info_a->group;
       stmt_vec_info stmtinfo_a = dr_info_a->stmt;
       stmt_vec_info lastinfo = NULL;
       if (!STMT_VINFO_VECTORIZABLE (stmtinfo_a)
@@ -2989,9 +2994,9 @@ vect_analyze_data_ref_accesses (vec_info *vinfo,
        }
       for (i = i + 1; i < datarefs_copy.length (); ++i)
        {
-         data_reference_p drb = datarefs_copy[i].first;
-         int drb_group_id = datarefs_copy[i].second;
-         dr_vec_info *dr_info_b = vinfo->lookup_dr (drb);
+         dr_vec_info *dr_info_b = datarefs_copy[i];
+         data_reference_p drb = dr_info_b->dr;
+         int drb_group_id = dr_info_b->group;
          stmt_vec_info stmtinfo_b = dr_info_b->stmt;
          if (!STMT_VINFO_VECTORIZABLE (stmtinfo_b)
              || STMT_VINFO_GATHER_SCATTER_P (stmtinfo_b))
@@ -3052,7 +3057,7 @@ vect_analyze_data_ref_accesses (vec_info *vinfo,
          HOST_WIDE_INT init_a = TREE_INT_CST_LOW (DR_INIT (dra));
          HOST_WIDE_INT init_b = TREE_INT_CST_LOW (DR_INIT (drb));
          HOST_WIDE_INT init_prev
-           = TREE_INT_CST_LOW (DR_INIT (datarefs_copy[i-1].first));
+           = TREE_INT_CST_LOW (DR_INIT (datarefs_copy[i-1]->dr));
          gcc_assert (init_a <= init_b
                      && init_a <= init_prev
                      && init_prev <= init_b);
@@ -3060,7 +3065,7 @@ vect_analyze_data_ref_accesses (vec_info *vinfo,
          /* Do not place the same access in the interleaving chain twice.  */
          if (init_b == init_prev)
            {
-             gcc_assert (gimple_uid (DR_STMT (datarefs_copy[i-1].first))
+             gcc_assert (gimple_uid (DR_STMT (datarefs_copy[i-1]->dr))
                          < gimple_uid (DR_STMT (drb)));
              /* Simply link in duplicates and fix up the chain below.  */
            }
@@ -3173,10 +3178,9 @@ vect_analyze_data_ref_accesses (vec_info *vinfo,
       to_fixup.add (newgroup);
     }
 
-  data_ref_pair *dr_pair;
-  FOR_EACH_VEC_ELT (datarefs_copy, i, dr_pair)
+  dr_vec_info *dr_info;
+  FOR_EACH_VEC_ELT (datarefs_copy, i, dr_info)
     {
-      dr_vec_info *dr_info = vinfo->lookup_dr (dr_pair->first);
       if (STMT_VINFO_VECTORIZABLE (dr_info->stmt)
          && !vect_analyze_data_ref_access (vinfo, dr_info))
        {

diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
index 9861d9e88102138c0e2de8dfc34422ff65a0e9e0..85f4762cd083af25d551040e316f7024637189da 100644 (file)
--- a/gcc/tree-vectorizer.h
+++ b/gcc/tree-vectorizer.h
@@ -106,10 +106,11 @@ struct stmt_info_for_cost {
 
 typedef vec<stmt_info_for_cost> stmt_vector_for_cost;
 
-/* Maps base addresses to an innermost_loop_behavior that gives the maximum
-   known alignment for that base.  */
+/* Maps base addresses to an innermost_loop_behavior and the stmt it was
+   derived from that gives the maximum known alignment for that base.  */
 typedef hash_map<tree_operand_hash,
-                innermost_loop_behavior *> vec_base_alignments;
+                std::pair<stmt_vec_info, innermost_loop_behavior *> >
+         vec_base_alignments;
 
 /************************************************************************
   SLP
@@ -1016,6 +1017,9 @@ public:
   data_reference *dr;
   /* The statement that contains the data reference.  */
   stmt_vec_info stmt;
+  /* The analysis group this DR belongs to when doing BB vectorization.
+     DRs of the same group belong to the same conditional execution context.  */
+  unsigned group;
   /* The misalignment in bytes of the reference, or -1 if not known.  */
   int misalignment;
   /* The byte alignment that we'd ideally like the reference to have,