x86-64: Add wcslen optimize for sse4.1

No bug. This comment adds the ifunc / build infrastructure
necessary for wcslen to prefer the sse4.1 implementation
in strlen-vec.S. test-wcslen.c is passing.

Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
(cherry picked from commit 6f573a27b6)

sysdeps/x86_64/multiarch/Makefile

@@ -97,8 +97,8 @@ sysdep_routines += wmemcmp-sse4 wmemcmp-ssse3 wmemcmp-c \
 		   wcscpy-ssse3 wcscpy-c \
 		   wcschr-sse2 wcschr-avx2 \
 		   wcsrchr-sse2 wcsrchr-avx2 \
-		   wcsnlen-sse4_1 wcsnlen-c \
+		   wcslen-sse2 wcslen-sse4_1 wcslen-avx2 \
-		   wcslen-sse2 wcslen-avx2 wcsnlen-avx2 \
+		   wcsnlen-c wcsnlen-sse4_1 wcsnlen-avx2 \
 		   wcschr-avx2-rtm \
 		   wcscmp-avx2-rtm \
 		   wcslen-avx2-rtm \

sysdeps/x86_64/multiarch/ifunc-impl-list.c

@@ -657,6 +657,9 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 			       && HAS_ARCH_FEATURE (AVX512BW_Usable)
 			       && HAS_CPU_FEATURE (BMI2)),
 			      __wcslen_evex)
+	      IFUNC_IMPL_ADD (array, i, wcsnlen,
+			      CPU_FEATURE_USABLE (SSE4_1),
+			      __wcsnlen_sse4_1)
 	      IFUNC_IMPL_ADD (array, i, wcslen, 1, __wcslen_sse2))
 
   /* Support sysdeps/x86_64/multiarch/wcsnlen.c.  */

sysdeps/x86_64/multiarch/ifunc-wcslen.h

@@ -0,0 +1,52 @@
+/* Common definition for ifunc selections for wcslen and wcsnlen
+   All versions must be listed in ifunc-impl-list.c.
+   Copyright (C) 2017-2021 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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <init-arch.h>
+
+extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2) attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE (sse4_1) attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE (avx2) attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE (avx2_rtm) attribute_hidden;
+extern __typeof (REDIRECT_NAME) OPTIMIZE (evex) attribute_hidden;
+
+static inline void *
+IFUNC_SELECTOR (void)
+{
+  const struct cpu_features* cpu_features = __get_cpu_features ();
+
+  if (CPU_FEATURES_ARCH_P (cpu_features, AVX2_Usable)
+      && CPU_FEATURES_CPU_P (cpu_features, BMI2)
+      && CPU_FEATURES_ARCH_P (cpu_features, AVX_Fast_Unaligned_Load))
+    {
+      if (CPU_FEATURES_ARCH_P (cpu_features, AVX512VL_Usable)
+	  && CPU_FEATURES_ARCH_P (cpu_features, AVX512BW_Usable))
+	return OPTIMIZE (evex);
+
+      if (CPU_FEATURES_CPU_P (cpu_features, RTM))
+	return OPTIMIZE (avx2_rtm);
+
+      if (!CPU_FEATURES_ARCH_P (cpu_features, Prefer_No_VZEROUPPER))
+	return OPTIMIZE (avx2);
+    }
+
+  if (CPU_FEATURES_CPU_P (cpu_features, SSE4_1))
+    return OPTIMIZE (sse4_1);
+
+  return OPTIMIZE (sse2);
+}

sysdeps/x86_64/multiarch/wcslen-sse4_1.S

@@ -0,0 +1,4 @@
+#define AS_WCSLEN
+#define strlen	__wcslen_sse4_1
+
+#include "strlen-vec.S"

sysdeps/x86_64/multiarch/wcslen.c

@@ -24,7 +24,7 @@
 # undef __wcslen
 
 # define SYMBOL_NAME wcslen
-# include "ifunc-avx2.h"
+# include "ifunc-wcslen.h"
 
 libc_ifunc_redirected (__redirect_wcslen, __wcslen, IFUNC_SELECTOR ());
 weak_alias (__wcslen, wcslen);

sysdeps/x86_64/multiarch/wcsnlen.c

@@ -24,39 +24,7 @@
 # undef __wcsnlen
 
 # define SYMBOL_NAME wcsnlen
-# include <init-arch.h>
+# include "ifunc-wcslen.h"
-
-extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2) attribute_hidden;
-extern __typeof (REDIRECT_NAME) OPTIMIZE (sse4_1) attribute_hidden;
-extern __typeof (REDIRECT_NAME) OPTIMIZE (avx2) attribute_hidden;
-extern __typeof (REDIRECT_NAME) OPTIMIZE (avx2_rtm) attribute_hidden;
-extern __typeof (REDIRECT_NAME) OPTIMIZE (evex) attribute_hidden;
-
-static inline void *
-IFUNC_SELECTOR (void)
-{
-  const struct cpu_features* cpu_features = __get_cpu_features ();
-
-  if (CPU_FEATURES_ARCH_P (cpu_features, AVX2_Usable)
-      && CPU_FEATURES_ARCH_P (cpu_features, AVX_Fast_Unaligned_Load))
-    {
-      if (CPU_FEATURES_ARCH_P (cpu_features, AVX512VL_Usable)
-	  && CPU_FEATURES_ARCH_P (cpu_features, AVX512BW_Usable)
-	  && CPU_FEATURES_CPU_P (cpu_features, BMI2))
-	return OPTIMIZE (evex);
-
-      if (CPU_FEATURES_CPU_P (cpu_features, RTM))
-	return OPTIMIZE (avx2_rtm);
-
-      if (!CPU_FEATURES_ARCH_P (cpu_features, Prefer_No_VZEROUPPER))
-	return OPTIMIZE (avx2);
-    }
-
-  if (CPU_FEATURES_CPU_P (cpu_features, SSE4_1))
-    return OPTIMIZE (sse4_1);
-
-  return OPTIMIZE (sse2);
-}
 
 libc_ifunc_redirected (__redirect_wcsnlen, __wcsnlen, IFUNC_SELECTOR ());
 weak_alias (__wcsnlen, wcsnlen);