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. --- string/tester.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'string/tester.c') diff --git a/string/tester.c b/string/tester.c index 778160a..605b3f0 100644 --- a/string/tester.c +++ b/string/tester.c @@ -1450,6 +1450,19 @@ test_bcmp (void) } static void +test_memcmpeq (void) +{ + it = "__memcmpeq"; + check (__memcmpeq ("a", "a", 1) == 0, 1); /* Identity. */ + check (__memcmpeq ("abc", "abc", 3) == 0, 2); /* Multicharacter. */ + check (__memcmpeq ("abcd", "abce", 4) != 0, 3); /* Honestly unequal. */ + check (__memcmpeq ("abce", "abcd", 4) != 0, 4); + check (__memcmpeq ("alph", "beta", 4) != 0, 5); + check (__memcmpeq ("abce", "abcd", 3) == 0, 6); /* Count limited. */ + check (__memcmpeq ("abc", "def", 0) == 0, 8); /* Zero count. */ +} + +static void test_strerror (void) { it = "strerror"; @@ -1611,6 +1624,9 @@ main (void) /* bcmp - somewhat like memcmp. */ test_bcmp (); + /* __memcmpeq - somewhat like memcmp. */ + test_memcmpeq (); + /* strndup. */ test_strndup (); -- cgit v1.1