From 2b438a0d2aa80f051a09b245a58f643540d4004b Mon Sep 17 00:00:00 2001
From: Robin Dapp <rdapp@ventanamicro.com>
Date: Fri, 7 Jun 2024 14:36:41 +0200
Subject: [PATCH] vect: Merge loop mask and cond_op mask in fold-left reduction
 [PR115382].

Currently we discard the cond-op mask when the loop is fully masked
which causes wrong code in
gcc.dg/vect/vect-cond-reduc-in-order-2-signed-zero.c
when compiled with
-O3 -march=cascadelake --param vect-partial-vector-usage=2.

This patch ANDs both masks.

gcc/ChangeLog:

	PR tree-optimization/115382

	* tree-vect-loop.cc (vectorize_fold_left_reduction): Use
	prepare_vec_mask.
	* tree-vect-stmts.cc (check_load_store_for_partial_vectors):
	Remove static of prepare_vec_mask.
	* tree-vectorizer.h (prepare_vec_mask): Export.
---
 gcc/tree-vect-loop.cc  | 10 +++++++++-
 gcc/tree-vect-stmts.cc |  2 +-
 gcc/tree-vectorizer.h  |  3 +++
 3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index c471f1564a7..5b1ad06eca6 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -7204,7 +7204,15 @@ vectorize_fold_left_reduction (loop_vec_info loop_vinfo,
       tree len = NULL_TREE;
       tree bias = NULL_TREE;
       if (LOOP_VINFO_FULLY_MASKED_P (loop_vinfo))
-	mask = vect_get_loop_mask (loop_vinfo, gsi, masks, vec_num, vectype_in, i);
+	{
+	  tree loop_mask = vect_get_loop_mask (loop_vinfo, gsi, masks,
+					       vec_num, vectype_in, i);
+	  if (is_cond_op)
+	    mask = prepare_vec_mask (loop_vinfo, TREE_TYPE (loop_mask),
+				     loop_mask, vec_opmask[i], gsi);
+	  else
+	    mask = loop_mask;
+	}
       else if (is_cond_op)
 	mask = vec_opmask[i];
       if (LOOP_VINFO_FULLY_WITH_LENGTH_P (loop_vinfo))
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index 05a169ecb2d..831f1825376 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -1643,7 +1643,7 @@ check_load_store_for_partial_vectors (loop_vec_info loop_vinfo, tree vectype,
    MASK_TYPE is the type of both masks.  If new statements are needed,
    insert them before GSI.  */
 
-static tree
+tree
 prepare_vec_mask (loop_vec_info loop_vinfo, tree mask_type, tree loop_mask,
 		  tree vec_mask, gimple_stmt_iterator *gsi)
 {
diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
index 97ec9c341e7..6bb0f5c3a56 100644
--- a/gcc/tree-vectorizer.h
+++ b/gcc/tree-vectorizer.h
@@ -2508,6 +2508,9 @@ extern void vect_free_slp_tree (slp_tree);
 extern bool compatible_calls_p (gcall *, gcall *);
 extern int vect_slp_child_index_for_operand (const gimple *, int op, bool);
 
+extern tree prepare_vec_mask (loop_vec_info, tree, tree, tree,
+			      gimple_stmt_iterator *);
+
 /* In tree-vect-patterns.cc.  */
 extern void
 vect_mark_pattern_stmts (vec_info *, stmt_vec_info, gimple *, tree);