From: Richard Biener <rguenther@suse.de>
Date: Thu, 2 Oct 2025 12:41:01 +0000 (+0200)
Subject: Disallow mask reduction vectorization
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e5ae5b5ba6f2af408717034d82c40839642667b0;p=thirdparty%2Fgcc.git

Disallow mask reduction vectorization

When you trick bool pattern recognition to use a mask type for a
reduction PHI you'll figure we're not ready to handle this because
epilogue creation isn't expecting this yet.  The following reverts
part of the last change and makes this explicit.

	* tree-vect-loop.cc (vectorizable_reduction): Do not allow
	mask reductions.
---

diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index 1d549e4a03e..df45adbe035 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -7177,6 +7177,15 @@ vectorizable_reduction (loop_vec_info loop_vinfo,
   tree vectype_out = SLP_TREE_VECTYPE (slp_for_stmt_info);
   VECT_REDUC_INFO_VECTYPE (reduc_info) = vectype_out;
 
+  /* We do not handle mask reductions correctly in the epilogue.  */
+  if (VECTOR_BOOLEAN_TYPE_P (vectype_out))
+    {
+      if (dump_enabled_p ())
+	dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+			 "mask reduction not supported.\n");
+      return false;
+    }
+
   gimple_match_op op;
   if (!gimple_extract_op (stmt_info->stmt, &op))
     gcc_unreachable ();
@@ -7187,8 +7196,7 @@ vectorizable_reduction (loop_vec_info loop_vinfo,
     return false;
 
   /* Do not try to vectorize bit-precision reductions.  */
-  if (!VECTOR_BOOLEAN_TYPE_P (vectype_out)
-      && !type_has_mode_precision_p (op.type)
+  if (!type_has_mode_precision_p (op.type)
       && op.code != BIT_AND_EXPR
       && op.code != BIT_IOR_EXPR
       && op.code != BIT_XOR_EXPR)