alpha: Add string-fza, string-fzb.h, string-fzi.h, and string-shift.h

While alpha has the more important string functions in assembly,
there are still a few for find the generic routines are used.

Use the CMPBGE insn, via the builtin, for testing of zeros.  Use a
simplified expansion of __builtin_ctz when the insn isn't available.

Checked on alpha-linux-gnu.

Co-authored-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

1 files changed, 60 insertions, 0 deletions

diff --git a/sysdeps/alpha/string-fza.h b/sysdeps/alpha/string-fza.h
new file mode 100644
index 0000000000..b72ce8293c
--- /dev/null
+++ b/sysdeps/alpha/string-fza.h
@@ -0,0 +1,60 @@
+/* Basic zero byte detection.  Generic C version.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _STRING_FZA_H
+#define _STRING_FZA_H 1
+
+#include <string-misc.h>
+#include <string-optype.h>
+
+/* The CMPBGE instruction creates a bit mask rather than a byte mask.
+   However, if we narrow find_t to either 'int' or 'uint8_t', we get
+   unnecessary truncation instructions from the 'unsigned long' type
+   returned by __builtin_alpha_cmpbge.  */
+typedef op_t find_t;
+
+static __always_inline find_t
+find_zero_all (op_t x)
+{
+  return __builtin_alpha_cmpbge (0, x);
+}
+
+static __always_inline find_t
+find_eq_all (op_t x1, op_t x2)
+{
+  return find_zero_all (x1 ^ x2);
+}
+
+static __always_inline find_t
+find_zero_eq_all (op_t x1, op_t x2)
+{
+  return find_zero_all (x1) | find_zero_all (x1 ^ x2);
+}
+
+static __always_inline find_t
+find_zero_ne_all (op_t x1, op_t x2)
+{
+  return find_zero_all (x1) | (find_zero_all (x1 ^ x2) ^ 0xff);
+}
+
+/* Define the "inexact" versions in terms of the exact versions.  */
+#define find_zero_low		find_zero_all
+#define find_eq_low		find_eq_all
+#define find_zero_eq_low	find_zero_eq_all
+
+#endif /* _STRING_FZA_H */