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From: Adhemerval Zanella <azanella@sourceware.org> To: glibc-cvs@sourceware.org Subject: [glibc/azanella/clang] string: Use asm alias instead of symbol redirections for stpcpy and mempcpy Date: Thu, 28 Sep 2023 17:51:27 +0000 (GMT) [thread overview] Message-ID: <20230928175127.ED8143882055@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=73fc2358d76908e448d74178728e154ea2e39218 commit 73fc2358d76908e448d74178728e154ea2e39218 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 most of affected ABIs. Diff: --- include/string.h | 4 ++-- sysdeps/unix/sysv/linux/sparc/sparc64/localplt.data | 3 +++ 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/include/string.h b/include/string.h index 86d1fa4abe..27f4e6e563 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/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
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