vect: Remove always-true condition
authorRichard Sandiford <richard.sandiford@arm.com>
Thu, 8 Jul 2021 11:58:13 +0000 (12:58 +0100)
committerRichard Sandiford <richard.sandiford@arm.com>
Thu, 8 Jul 2021 11:58:13 +0000 (12:58 +0100)
vectorizable_reduction had code guarded by:

  if (STMT_VINFO_DEF_TYPE (stmt_info) == vect_reduction_def
      || STMT_VINFO_DEF_TYPE (stmt_info) == vect_double_reduction_def)

But that's always true after:

  if (STMT_VINFO_DEF_TYPE (stmt_info) != vect_reduction_def
      && STMT_VINFO_DEF_TYPE (stmt_info) != vect_double_reduction_def
      && STMT_VINFO_DEF_TYPE (stmt_info) != vect_nested_cycle)
    return false;

  if (STMT_VINFO_DEF_TYPE (stmt_info) == vect_nested_cycle)
    {
      …
      return true;
    }

(I wasn't sure at first how the empty “else” for the first “if” above
was supposed to work.)

gcc/
* tree-vect-loop.c (vectorizable_reduction): Remove always-true
if condition.

gcc/tree-vect-loop.c

index 51a46a6..bc523d1 100644 (file)
@@ -6516,33 +6516,31 @@ vectorizable_reduction (loop_vec_info loop_vinfo,
 
   stmt_vec_info orig_stmt_of_analysis = stmt_info;
   stmt_vec_info phi_info = stmt_info;
-  if (STMT_VINFO_DEF_TYPE (stmt_info) == vect_reduction_def
-      || STMT_VINFO_DEF_TYPE (stmt_info) == vect_double_reduction_def)
+  if (!is_a <gphi *> (stmt_info->stmt))
     {
-      if (!is_a <gphi *> (stmt_info->stmt))
-       {
-         STMT_VINFO_TYPE (stmt_info) = reduc_vec_info_type;
-         return true;
-       }
-      if (slp_node)
-       {
-         slp_node_instance->reduc_phis = slp_node;
-         /* ???  We're leaving slp_node to point to the PHIs, we only
-            need it to get at the number of vector stmts which wasn't
-            yet initialized for the instance root.  */
-       }
-      if (STMT_VINFO_DEF_TYPE (stmt_info) == vect_reduction_def)
-       stmt_info = vect_stmt_to_vectorize (STMT_VINFO_REDUC_DEF (stmt_info));
-      else /* STMT_VINFO_DEF_TYPE (stmt_info) == vect_double_reduction_def */
-       {
-         use_operand_p use_p;
-         gimple *use_stmt;
-         bool res = single_imm_use (gimple_phi_result (stmt_info->stmt),
-                                    &use_p, &use_stmt);
-         gcc_assert (res);
-         phi_info = loop_vinfo->lookup_stmt (use_stmt);
-         stmt_info = vect_stmt_to_vectorize (STMT_VINFO_REDUC_DEF (phi_info));
-       }
+      STMT_VINFO_TYPE (stmt_info) = reduc_vec_info_type;
+      return true;
+    }
+  if (slp_node)
+    {
+      slp_node_instance->reduc_phis = slp_node;
+      /* ???  We're leaving slp_node to point to the PHIs, we only
+        need it to get at the number of vector stmts which wasn't
+        yet initialized for the instance root.  */
+    }
+  if (STMT_VINFO_DEF_TYPE (stmt_info) == vect_reduction_def)
+    stmt_info = vect_stmt_to_vectorize (STMT_VINFO_REDUC_DEF (stmt_info));
+  else
+    {
+      gcc_assert (STMT_VINFO_DEF_TYPE (stmt_info)
+                 == vect_double_reduction_def);
+      use_operand_p use_p;
+      gimple *use_stmt;
+      bool res = single_imm_use (gimple_phi_result (stmt_info->stmt),
+                                &use_p, &use_stmt);
+      gcc_assert (res);
+      phi_info = loop_vinfo->lookup_stmt (use_stmt);
+      stmt_info = vect_stmt_to_vectorize (STMT_VINFO_REDUC_DEF (phi_info));
     }
 
   /* PHIs should not participate in patterns.  */