x86-64: Optimize strcat/strncat, strcpy/strncpy and stpcpy/stpncpy with AVX2

Optimize x86-64 strcat/strncat, strcpy/strncpy and stpcpy/stpncpy with AVX2.
It uses vector comparison as much as possible. In general, the larger the
source string, the greater performance gain observed, reaching speedups of
1.6x compared to SSE2 unaligned routines. Select AVX2 strcat/strncat,
strcpy/strncpy and stpcpy/stpncpy on AVX2 machines where vzeroupper is
preferred and AVX unaligned load is fast.

	* sysdeps/x86_64/multiarch/Makefile (sysdep_routines): Add
	strcat-avx2, strncat-avx2, strcpy-avx2, strncpy-avx2,
	stpcpy-avx2 and stpncpy-avx2.
	* sysdeps/x86_64/multiarch/ifunc-impl-list.c:
	(__libc_ifunc_impl_list): Add tests for __strcat_avx2,
	__strncat_avx2, __strcpy_avx2, __strncpy_avx2, __stpcpy_avx2
	and __stpncpy_avx2.
	* sysdeps/x86_64/multiarch/{ifunc-unaligned-ssse3.h =>
	ifunc-strcpy.h}: rename header for a more generic name.
	* sysdeps/x86_64/multiarch/ifunc-strcpy.h:
	(IFUNC_SELECTOR): Return OPTIMIZE (avx2) on AVX 2 machines if
	AVX unaligned load is fast and vzeroupper is preferred.
	* sysdeps/x86_64/multiarch/stpcpy-avx2.S: New file
	* sysdeps/x86_64/multiarch/stpncpy-avx2.S: Likewise
	* sysdeps/x86_64/multiarch/strcat-avx2.S: Likewise
	* sysdeps/x86_64/multiarch/strcpy-avx2.S: Likewise
	* sysdeps/x86_64/multiarch/strncat-avx2.S: Likewise
	* sysdeps/x86_64/multiarch/strncpy-avx2.S: Likewise

1 files changed, 46 insertions, 0 deletions

diff --git a/sysdeps/x86_64/multiarch/ifunc-strcpy.h b/sysdeps/x86_64/multiarch/ifunc-strcpy.h
new file mode 100644
index 0000000000..bc6a70fc7c
--- /dev/null
+++ b/sysdeps/x86_64/multiarch/ifunc-strcpy.h
@@ -0,0 +1,46 @@
+/* Common definition for ifunc selections optimized with SSE2, unaligned
+   SSE2 and SSSE3.
+   All versions must be listed in ifunc-impl-list.c.
+   Copyright (C) 2017-2019 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/>.  */
+
+#include <init-arch.h>
+
+extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2) attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2_unaligned)
+  attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE (ssse3) attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE (avx2) attribute_hidden;
+
+static inline void *
+IFUNC_SELECTOR (void)
+{
+  const struct cpu_features* cpu_features = __get_cpu_features ();
+
+  if (!CPU_FEATURES_ARCH_P (cpu_features, Prefer_No_VZEROUPPER)
+      && CPU_FEATURES_ARCH_P (cpu_features, AVX2_Usable)
+      && CPU_FEATURES_ARCH_P (cpu_features, AVX_Fast_Unaligned_Load))
+    return OPTIMIZE (avx2);
+
+  if (CPU_FEATURES_ARCH_P (cpu_features, Fast_Unaligned_Load))
+    return OPTIMIZE (sse2_unaligned);
+
+  if (CPU_FEATURES_CPU_P (cpu_features, SSSE3))
+    return OPTIMIZE (ssse3);
+
+  return OPTIMIZE (sse2);
+}