[glibc/azanella/clang] string: Use asm alias instead of symbol redirections for stpcpy and mempcpy

[Adhemerval Zanella]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=5e40fc59009c7247b974d161ba50da4c237b66a6

commit 5e40fc59009c7247b974d161ba50da4c237b66a6
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Tue Mar 15 08:41:43 2022 -0300

    string: Use asm alias instead of symbol redirections for stpcpy and mempcpy
    
    Commit 939da411433 added symbols redirections to handle ISO C
    namespace, however some compiler does not support to redeclare the
    function prototype.  Moving these defintions to exported header
    it not a good practice (it exposes a internal implementation and
    it would require to add macros to define it only internally).
    
    Instead this patch replaces the symbol redirections by direct asm
    aliases, as done to handle libcall generation done by compiler on
    some loop optimizations. The only issue is sparc binutils generates
    an extra __mempcpy plt not called anywhere in the code, which indicates
    a binutils issue (this is added in the localplt.data for now).
    
    Checked on all affected ABIs.

Diff:
---
 include/string.h                                    | 4 ++--
 sysdeps/unix/sysv/linux/sparc/sparc32/localplt.data | 3 +++
 sysdeps/unix/sysv/linux/sparc/sparc64/localplt.data | 3 +++
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/string.h b/include/string.h
index 3b4c6007d7..082865caad 100644
--- a/include/string.h
+++ b/include/string.h
@@ -179,8 +179,8 @@ extern __typeof (strsep) strsep attribute_hidden;
   && !defined NO_MEMPCPY_STPCPY_REDIRECT
 /* Redirect calls to __builtin_mempcpy and __builtin_stpcpy to call
    __mempcpy and __stpcpy if not inlined.  */
-extern __typeof (mempcpy) mempcpy __asm__ ("__mempcpy");
-extern __typeof (stpcpy) stpcpy __asm__ ("__stpcpy");
+__asm__ ("mempcpy = __mempcpy");
+__asm__ ("stpcpy = __stpcpy");
 #endif
 
 extern void *__memcpy_chk (void *__restrict __dest,
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/localplt.data b/sysdeps/unix/sysv/linux/sparc/sparc32/localplt.data
index b5fc6d9c3a..327276d9c2 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/localplt.data
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/localplt.data
@@ -17,4 +17,7 @@ libc.so: calloc
 libc.so: free
 libc.so: malloc
 libc.so: realloc
+# Unreferenced PLT created by the symbols aliases used to redirect
+# the compiler generated mempcpy/stpcyp calls done by builtin usage.
+libc.so: __mempcpy
 libm.so: matherr
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/localplt.data b/sysdeps/unix/sysv/linux/sparc/sparc64/localplt.data
index 15c0f8ccf7..e7ab61dcbe 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/localplt.data
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/localplt.data
@@ -17,4 +17,7 @@ libc.so: calloc
 libc.so: free
 libc.so: malloc
 libc.so: realloc
+# Unreferenced PLT created by the symbols aliases used to redirect
+# the compiler generated mempcpy/stpcyp calls done by builtin usage.
+libc.so: __mempcpy
 libm.so: matherr