[PATCH v6 16/17] powerpc: Add string-fza.h

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

From: Richard Henderson <richard.henderson@linaro.org>

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

Use the Power 6 CMPB insn for testing of zeros.

Checked on powerpc64le-linux-gnu.
---
 sysdeps/powerpc/string-fza.h | 70 ++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 sysdeps/powerpc/string-fza.h

diff --git a/sysdeps/powerpc/string-fza.h b/sysdeps/powerpc/string-fza.h
new file mode 100644
index 0000000000..5496c9db4b
--- /dev/null
+++ b/sysdeps/powerpc/string-fza.h
@@ -0,0 +1,70 @@
+/* Zero byte detection; basics.  PowerPC 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 _POWERPC_STRING_FZA_H
+#define _POWERPC_STRING_FZA_H 1
+
+/* PowerISA 2.05 (POWER6) provides cmpb instruction.  */
+#ifdef _ARCH_PWR6
+# include <string-optype.h>
+
+/* This function returns 0xff for each byte that is
+   equal between X1 and X2.  */
+
+static __always_inline op_t
+find_eq_all (op_t x1, op_t x2)
+{
+  op_t ret;
+  asm ("cmpb %0,%1,%2" : "=r"(ret) : "r"(x1), "r"(x2));
+  return ret;
+}
+
+/* This function returns 0xff for each byte that is zero in X.  */
+
+static __always_inline op_t
+find_zero_all (op_t x)
+{
+  return find_eq_all (x, 0);
+}
+
+/* Identify zero bytes in X1 or equality between X1 and X2.  */
+
+static __always_inline op_t
+find_zero_eq_all (op_t x1, op_t x2)
+{
+  return find_zero_all (x1) | find_eq_all (x1, x2);
+}
+
+/* Identify zero bytes in X1 or inequality between X1 and X2.  */
+
+static __always_inline op_t
+find_zero_ne_all (op_t x1, op_t x2)
+{
+  return find_zero_all (x1) | ~find_eq_all (x1, x2);
+}
+
+/* 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
+# define find_zero_ne_low	find_zero_ne_all
+#else
+# include <sysdeps/generic/string-fza.h>
+#endif /* _ARCH_PWR6  */
+
+#endif /* _POWERPC_STRING_FZA_H  */
-- 
2.34.1