From 44829b3ddb64e99e37343a0f25b2c082387d31a5 Mon Sep 17 00:00:00 2001 From: Noah Goldstein Date: Thu, 21 Oct 2021 15:54:57 -0500 Subject: String: Add support for __memcmpeq() ABI on all targets No bug. This commit adds support for __memcmpeq() as a new ABI for all targets. In this commit __memcmpeq() is implemented only as an alias to the corresponding targets memcmp() implementation. __memcmpeq() is added as a new symbol starting with GLIBC_2.35 and defined in string.h with comments explaining its behavior. Basic tests that it is callable and works where added in string/tester.c As discussed in the proposal "Add new ABI '__memcmpeq()' to libc" __memcmpeq() is essentially a reserved namespace for bcmp(). The means is shares the same specifications as memcmp() except the return value for non-equal byte sequences is any non-zero value. This is less strict than memcmp()'s return value specification and can be better optimized when a boolean return is all that is needed. __memcmpeq() is meant to only be called by compilers if they can prove that the return value of a memcmp() call is only used for its boolean value. All tests in string/tester.c passed. As well build succeeds on x86_64-linux-gnu target. --- sysdeps/i386/i686/memcmp.S | 2 ++ sysdeps/i386/i686/multiarch/memcmp-ia32.S | 3 +++ sysdeps/i386/i686/multiarch/memcmp.c | 1 + sysdeps/i386/memcmp.S | 2 ++ 4 files changed, 8 insertions(+) (limited to 'sysdeps/i386') diff --git a/sysdeps/i386/i686/memcmp.S b/sysdeps/i386/i686/memcmp.S index b26b124..90266d9 100644 --- a/sysdeps/i386/i686/memcmp.S +++ b/sysdeps/i386/i686/memcmp.S @@ -405,4 +405,6 @@ L(table_32bytes) : #undef bcmp weak_alias (memcmp, bcmp) +#undef __memcmpeq +strong_alias (memcmp, __memcmpeq) libc_hidden_builtin_def (memcmp) diff --git a/sysdeps/i386/i686/multiarch/memcmp-ia32.S b/sysdeps/i386/i686/multiarch/memcmp-ia32.S index 5f6658b..a5b5c3d 100644 --- a/sysdeps/i386/i686/multiarch/memcmp-ia32.S +++ b/sysdeps/i386/i686/multiarch/memcmp-ia32.S @@ -30,6 +30,9 @@ # undef weak_alias # define weak_alias(original, alias) + +# undef strong_alias +# define strong_alias(original, alias) #endif #include diff --git a/sysdeps/i386/i686/multiarch/memcmp.c b/sysdeps/i386/i686/multiarch/memcmp.c index 6e058a8..3b2815e 100644 --- a/sysdeps/i386/i686/multiarch/memcmp.c +++ b/sysdeps/i386/i686/multiarch/memcmp.c @@ -29,4 +29,5 @@ libc_ifunc_redirected (__redirect_memcmp, memcmp, IFUNC_SELECTOR ()); weak_alias (memcmp, bcmp) +strong_alias (memcmp, __memcmpeq) #endif diff --git a/sysdeps/i386/memcmp.S b/sysdeps/i386/memcmp.S index 1f212b0..02473c2 100644 --- a/sysdeps/i386/memcmp.S +++ b/sysdeps/i386/memcmp.S @@ -70,4 +70,6 @@ END (memcmp) #undef bcmp weak_alias (memcmp, bcmp) +#undef __memcmpeq +strong_alias (memcmp, __memcmpeq) libc_hidden_builtin_def (memcmp) -- cgit v1.1