[glibc] string: Improve generic strcpy

[Adhemerval Zanella <azanella@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=3709ed904770b440d68385f3da259008cdf642a6

commit 3709ed904770b440d68385f3da259008cdf642a6
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Tue Jan 31 16:28:42 2023 -0300

    string: Improve generic strcpy
    
    Now that stpcpy is vectorized based on op_t, it should be better to
    call it instead of strlen plus memcpy.
    
    Checked on x86_64-linux-gnu, i686-linux-gnu, powerpc64-linux-gnu,
    and powerpc-linux-gnu by removing the arch-specific assembly
    implementation and disabling multi-arch (it covers both LE and BE
    for 64 and 32 bits).
    
    Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
    Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>

Diff:
---
 string/strcpy.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/string/strcpy.c b/string/strcpy.c
index 0345c71d15..d945d8fdf0 100644
--- a/string/strcpy.c
+++ b/string/strcpy.c
@@ -19,6 +19,9 @@
 #include <string.h>
 
 #undef strcpy
+/* Disable internal stpcpy optimization, otherwise the __stpcpy might it
+   generate a strcpy call.  */
+#undef __stpcpy
 
 #ifndef STRCPY
 # define STRCPY strcpy
@@ -28,6 +31,7 @@
 char *
 STRCPY (char *dest, const char *src)
 {
-  return memcpy (dest, src, strlen (src) + 1);
+  __stpcpy (dest, src);
+  return dest;
 }
 libc_hidden_builtin_def (strcpy)