[libc] Add memcmp implementation.
Reviewed By: gchatelet
Differential Revision: https://reviews.llvm.org/D93009
GitOrigin-RevId: af68c3b8924218596ecee948cc22cbb2c69c7f42
diff --git a/config/linux/aarch64/entrypoints.txt b/config/linux/aarch64/entrypoints.txt
index 534a4bd..89f910b 100644
--- a/config/linux/aarch64/entrypoints.txt
+++ b/config/linux/aarch64/entrypoints.txt
@@ -26,6 +26,7 @@
# string.h entrypoints
libc.src.string.bzero
libc.src.string.memchr
+ libc.src.string.memcmp
libc.src.string.memcpy
libc.src.string.memset
libc.src.string.memrchr
diff --git a/config/linux/x86_64/entrypoints.txt b/config/linux/x86_64/entrypoints.txt
index fce2823..d5a2f29 100644
--- a/config/linux/x86_64/entrypoints.txt
+++ b/config/linux/x86_64/entrypoints.txt
@@ -48,6 +48,7 @@
# string.h entrypoints
libc.src.string.bzero
libc.src.string.memchr
+ libc.src.string.memcmp
libc.src.string.memcpy
libc.src.string.memrchr
libc.src.string.memset
diff --git a/src/string/CMakeLists.txt b/src/string/CMakeLists.txt
index 94df8a9..683b857 100644
--- a/src/string/CMakeLists.txt
+++ b/src/string/CMakeLists.txt
@@ -59,6 +59,14 @@
)
add_entrypoint_object(
+ memcmp
+ SRCS
+ memcmp.cpp
+ HDRS
+ memcmp.h
+)
+
+add_entrypoint_object(
strchr
SRCS
strchr.cpp
diff --git a/src/string/memcmp.cpp b/src/string/memcmp.cpp
new file mode 100644
index 0000000..1bd1c60
--- /dev/null
+++ b/src/string/memcmp.cpp
@@ -0,0 +1,27 @@
+//===-- Implementation of memcmp ------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/string/memcmp.h"
+#include "src/__support/common.h"
+#include <stddef.h> // size_t
+
+namespace __llvm_libc {
+
+// TODO: It is a simple implementation, an optimized version is preparing.
+int LLVM_LIBC_ENTRYPOINT(memcmp)(const void *lhs, const void *rhs,
+ size_t count) {
+ const unsigned char *_lhs = reinterpret_cast<const unsigned char *>(lhs);
+ const unsigned char *_rhs = reinterpret_cast<const unsigned char *>(rhs);
+ for (size_t i = 0; i < count; ++i)
+ if (_lhs[i] != _rhs[i])
+ return _lhs[i] - _rhs[i];
+ // count is 0 or _lhs and _rhs are the same.
+ return 0;
+}
+
+} // namespace __llvm_libc
diff --git a/src/string/memcmp.h b/src/string/memcmp.h
new file mode 100644
index 0000000..1d79df5
--- /dev/null
+++ b/src/string/memcmp.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for memcmp ------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_STRING_MEMCMP_H
+#define LLVM_LIBC_SRC_STRING_MEMCMP_H
+
+#include <stddef.h> // size_t
+
+namespace __llvm_libc {
+
+int memcmp(const void *lhs, const void *rhs, size_t count);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_STRING_MEMCMP_H
diff --git a/test/src/string/CMakeLists.txt b/test/src/string/CMakeLists.txt
index 8b78fcf..8202c69 100644
--- a/test/src/string/CMakeLists.txt
+++ b/test/src/string/CMakeLists.txt
@@ -53,6 +53,16 @@
)
add_libc_unittest(
+ memcmp_test
+ SUITE
+ libc_string_unittests
+ SRCS
+ memcmp_test.cpp
+ DEPENDS
+ libc.src.string.memcmp
+)
+
+add_libc_unittest(
strchr_test
SUITE
libc_string_unittests
diff --git a/test/src/string/memcmp_test.cpp b/test/src/string/memcmp_test.cpp
new file mode 100644
index 0000000..3cfde0e
--- /dev/null
+++ b/test/src/string/memcmp_test.cpp
@@ -0,0 +1,34 @@
+//===-- Unittests for memcmp ----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/string/memcmp.h"
+#include "utils/UnitTest/Test.h"
+
+TEST(MemcmpTest, CmpZeroByte) {
+ const char *lhs = "ab";
+ const char *rhs = "bc";
+ EXPECT_EQ(__llvm_libc::memcmp(lhs, rhs, 0), 0);
+}
+
+TEST(MemcmpTest, LhsRhsAreTheSame) {
+ const char *lhs = "ab";
+ const char *rhs = "ab";
+ EXPECT_EQ(__llvm_libc::memcmp(lhs, rhs, 2), 0);
+}
+
+TEST(MemcmpTest, LhsBeforeRhsLexically) {
+ const char *lhs = "ab";
+ const char *rhs = "ac";
+ EXPECT_EQ(__llvm_libc::memcmp(lhs, rhs, 2), -1);
+}
+
+TEST(MemcmpTest, LhsAfterRhsLexically) {
+ const char *lhs = "ac";
+ const char *rhs = "ab";
+ EXPECT_EQ(__llvm_libc::memcmp(lhs, rhs, 2), 1);
+}
