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authorNoah Goldstein <goldstein.w.n@gmail.com>2021-10-21 15:54:57 -0500
committerNoah Goldstein <goldstein.w.n@gmail.com>2021-10-26 16:51:29 -0500
commit44829b3ddb64e99e37343a0f25b2c082387d31a5 (patch)
treeba9565215210f530296dd4456816fc69f593e542 /sysdeps/i386
parent8438135d3481853e300e1043cfee3946dadb28b3 (diff)
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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.
Diffstat (limited to 'sysdeps/i386')
-rw-r--r--sysdeps/i386/i686/memcmp.S2
-rw-r--r--sysdeps/i386/i686/multiarch/memcmp-ia32.S3
-rw-r--r--sysdeps/i386/i686/multiarch/memcmp.c1
-rw-r--r--sysdeps/i386/memcmp.S2
4 files changed, 8 insertions, 0 deletions
diff --git a/sysdeps/i386/i686/memcmp.S b/sysdeps/i386/i686/memcmp.S
index b26b124fad..90266d904b 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 5f6658b89a..a5b5c3d349 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 <sysdeps/i386/i686/memcmp.S>
diff --git a/sysdeps/i386/i686/multiarch/memcmp.c b/sysdeps/i386/i686/multiarch/memcmp.c
index 6e058a8857..3b2815edbc 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 1f212b0f6d..02473c2c0c 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)