[PATCH 3/6] vect: Set STMT_VINFO_REDUC_DEF for non-live stmt in loop reduction

[Feng Xue OS]

Normally, vectorizable checking on statement in a loop reduction chain does
not use the reduction PHI information. But some special statements might
need it in vectorizable analysis, especially, for multiple lane-reducing
operations support later.

Thanks,
Feng
---
gcc/
        * tree-vect-loop.cc (vectorizable_reduction): Set STMT_VINFO_REDUC_DEF
        for non-live stmt.
        * tree-vect-stmts.cc (vectorizable_condition): Treat the condition
        statement that is pointed by stmt_vec_info of reduction PHI as the
        real "for_reduction" statement.
---
 gcc/tree-vect-loop.cc  |  5 +++--
 gcc/tree-vect-stmts.cc | 11 ++++++++++-
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index aa5f21ccd1a..51627c27f8a 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -7632,14 +7632,15 @@ vectorizable_reduction (loop_vec_info loop_vinfo,
         all lanes here - even though we only will vectorize from
         the SLP node with live lane zero the other live lanes also
         need to be identified as part of a reduction to be able
-        to skip code generation for them.  */
+        to skip code generation for them.  For lane-reducing operation
+        vectorizable analysis needs the reduction PHI information.  */
       if (slp_for_stmt_info)
        {
          for (auto s : SLP_TREE_SCALAR_STMTS (slp_for_stmt_info))
            if (STMT_VINFO_LIVE_P (s))
              STMT_VINFO_REDUC_DEF (vect_orig_stmt (s)) = phi_info;
        }
-      else if (STMT_VINFO_LIVE_P (vdef))
+      else
        STMT_VINFO_REDUC_DEF (def) = phi_info;
       gimple_match_op op;
       if (!gimple_extract_op (vdef->stmt, &op))
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index 935d80f0e1b..2e0be763abb 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -12094,11 +12094,20 @@ vectorizable_condition (vec_info *vinfo,
   vect_reduction_type reduction_type = TREE_CODE_REDUCTION;
   bool for_reduction
     = STMT_VINFO_REDUC_DEF (vect_orig_stmt (stmt_info)) != NULL;
+  if (for_reduction)
+    {
+      reduc_info = info_for_reduction (vinfo, stmt_info);
+      if (STMT_VINFO_REDUC_DEF (reduc_info) != vect_orig_stmt (stmt_info))
+       {
+         for_reduction = false;
+         reduc_info = NULL;
+       }
+    }
+
   if (for_reduction)
     {
       if (slp_node)
        return false;
-      reduc_info = info_for_reduction (vinfo, stmt_info);
       reduction_type = STMT_VINFO_REDUC_TYPE (reduc_info);
       reduc_index = STMT_VINFO_REDUC_IDX (stmt_info);
       gcc_assert (reduction_type != EXTRACT_LAST_REDUCTION
-- 
2.17.1