[libc-commits] [libc] 5a9630b - [libc] Adds implementation for memrchr.
via libc-commits
libc-commits at lists.llvm.org
Fri Jul 24 11:41:10 PDT 2020
Author: cgyurgyik
Date: 2020-07-24T14:40:12-04:00
New Revision: 5a9630b7774dbacb7a0bdba068c1b26c231558bc
URL: https://github.com/llvm/llvm-project/commit/5a9630b7774dbacb7a0bdba068c1b26c231558bc
DIFF: https://github.com/llvm/llvm-project/commit/5a9630b7774dbacb7a0bdba068c1b26c231558bc.diff
LOG: [libc] Adds implementation for memrchr.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D84469
Added:
libc/src/string/memrchr.cpp
libc/src/string/memrchr.h
libc/test/src/string/memrchr_test.cpp
Modified:
libc/config/linux/aarch64/entrypoints.txt
libc/config/linux/api.td
libc/config/linux/x86_64/entrypoints.txt
libc/spec/gnu_ext.td
libc/src/string/CMakeLists.txt
libc/test/src/string/CMakeLists.txt
Removed:
################################################################################
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 6a1ff3bd64a9..b287a72d779b 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -13,6 +13,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.string.strchr
libc.src.string.strstr
libc.src.string.strnlen
+ libc.src.string.memrchr
)
set(TARGET_LIBM_ENTRYPOINTS
diff --git a/libc/config/linux/api.td b/libc/config/linux/api.td
index 1ec1a024f85d..5f7a858d5fa3 100644
--- a/libc/config/linux/api.td
+++ b/libc/config/linux/api.td
@@ -216,7 +216,8 @@ def StringAPI : PublicAPI<"string.h"> {
"strtok",
"strerror",
"strlen",
- "strnlen"
+ "strnlen",
+ "memrchr"
];
let TypeDeclarations = [
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index b20f58c45184..db5300530489 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -31,6 +31,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.string.strchr
libc.src.string.strstr
libc.src.string.strnlen
+ libc.src.string.memrchr
# sys/mman.h entrypoints
libc.src.sys.mman.mmap
diff --git a/libc/spec/gnu_ext.td b/libc/spec/gnu_ext.td
index 7ac99783bc47..d85c562d9256 100644
--- a/libc/spec/gnu_ext.td
+++ b/libc/spec/gnu_ext.td
@@ -12,8 +12,22 @@ def GnuExtensions : StandardSpec<"GNUExtensions"> {
>,
]
>;
+
+ HeaderSpec String = HeaderSpec<
+ "string.h",
+ [], // Macros
+ [], // Types
+ [], // Enumerations
+ [
+ FunctionSpec<
+ "memrchr",
+ RetValSpec<VoidPtr>,
+ [ArgSpec<VoidPtr>, ArgSpec<IntType>, ArgSpec<SizeTType>]
+ >,
+ ]
+ >;
let Headers = [
- Math,
+ Math, String,
];
}
diff --git a/libc/src/string/CMakeLists.txt b/libc/src/string/CMakeLists.txt
index 8bd7c1c045cf..99450d556459 100644
--- a/libc/src/string/CMakeLists.txt
+++ b/libc/src/string/CMakeLists.txt
@@ -78,6 +78,14 @@ add_entrypoint_object(
.memchr
)
+add_entrypoint_object(
+ memrchr
+ SRCS
+ memrchr.cpp
+ HDRS
+ memrchr.h
+)
+
# Helper to define a function with multiple implementations
# - Computes flags to satisfy required/rejected features and arch,
# - Declares an entry point,
diff --git a/libc/src/string/memrchr.cpp b/libc/src/string/memrchr.cpp
new file mode 100644
index 000000000000..81b034505202
--- /dev/null
+++ b/libc/src/string/memrchr.cpp
@@ -0,0 +1,26 @@
+//===-- Implementation of memrchr -----------------------------------------===//
+//
+// 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/memrchr.h"
+#include "src/__support/common.h"
+#include <stddef.h>
+
+namespace __llvm_libc {
+
+void *LLVM_LIBC_ENTRYPOINT(memrchr)(const void *src, int c, size_t n) {
+ const unsigned char *str = reinterpret_cast<const unsigned char *>(src);
+ const unsigned char ch = c;
+ for (; n != 0; --n) {
+ const unsigned char *s = str + n - 1;
+ if (*s == ch)
+ return const_cast<unsigned char *>(s);
+ }
+ return nullptr;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/string/memrchr.h b/libc/src/string/memrchr.h
new file mode 100644
index 000000000000..8f43577e331f
--- /dev/null
+++ b/libc/src/string/memrchr.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for memrchr -----------------------*- 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_MEMRCHR_H
+#define LLVM_LIBC_SRC_STRING_MEMRCHR_H
+
+#include <stddef.h>
+
+namespace __llvm_libc {
+
+void *memrchr(const void *src, int c, size_t n);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_STRING_MEMRCHR_H
diff --git a/libc/test/src/string/CMakeLists.txt b/libc/test/src/string/CMakeLists.txt
index be43cc912b5a..a116effef271 100644
--- a/libc/test/src/string/CMakeLists.txt
+++ b/libc/test/src/string/CMakeLists.txt
@@ -82,6 +82,16 @@ add_libc_unittest(
libc.src.string.strnlen
)
+add_libc_unittest(
+ memrchr_test
+ SUITE
+ libc_string_unittests
+ SRCS
+ memrchr_test.cpp
+ DEPENDS
+ libc.src.string.memrchr
+)
+
# Tests all implementations that can run on the host.
function(add_libc_multi_impl_test name)
get_property(fq_implementations GLOBAL PROPERTY ${name}_implementations)
diff --git a/libc/test/src/string/memrchr_test.cpp b/libc/test/src/string/memrchr_test.cpp
new file mode 100644
index 000000000000..5f5f7a0d0182
--- /dev/null
+++ b/libc/test/src/string/memrchr_test.cpp
@@ -0,0 +1,114 @@
+//===-- Unittests for memrchr ---------------------------------------------===//
+//
+// 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/memrchr.h"
+#include "utils/UnitTest/Test.h"
+#include <stddef.h>
+
+// A helper function that calls memrchr and abstracts away the explicit cast for
+// readability purposes.
+const char *call_memrchr(const void *src, int c, size_t size) {
+ return reinterpret_cast<const char *>(__llvm_libc::memrchr(src, c, size));
+}
+
+TEST(MemRChrTest, FindsCharacterAfterNullTerminator) {
+ // memrchr should continue searching after a null terminator.
+ const size_t size = 6;
+ const unsigned char src[size] = {'a', '\0', 'b', 'c', 'd', '\0'};
+ // Should return 'b', 'c', 'd', '\0' even when after null terminator.
+ ASSERT_STREQ(call_memrchr(src, 'b', size), "bcd");
+}
+
+TEST(MemRChrTest, FindsCharacterInNonNullTerminatedCollection) {
+ const size_t size = 3;
+ const unsigned char src[size] = {'a', 'b', 'c'};
+ // Should return 'b', 'c'.
+ const char *ret = call_memrchr(src, 'b', size);
+ ASSERT_EQ(ret[0], 'b');
+ ASSERT_EQ(ret[1], 'c');
+}
+
+TEST(MemRChrTest, FindsFirstCharacter) {
+ const size_t size = 6;
+ const unsigned char src[size] = {'a', 'b', 'c', 'd', 'e', '\0'};
+ // Should return original array since 'a' is the first character.
+ ASSERT_STREQ(call_memrchr(src, 'a', size), "abcde");
+}
+
+TEST(MemRChrTest, FindsMiddleCharacter) {
+ const size_t size = 6;
+ const unsigned char src[size] = {'a', 'b', 'c', 'd', 'e', '\0'};
+ // Should return characters after (and including) 'c'.
+ ASSERT_STREQ(call_memrchr(src, 'c', size), "cde");
+}
+
+TEST(MemRChrTest, FindsLastCharacterThatIsNotNullTerminator) {
+ const size_t size = 6;
+ const unsigned char src[size] = {'a', 'b', 'c', 'd', 'e', '\0'};
+ // Should return 'e' and null-terminator.
+ ASSERT_STREQ(call_memrchr(src, 'e', size), "e");
+}
+
+TEST(MemRChrTest, FindsNullTerminator) {
+ const size_t size = 6;
+ const unsigned char src[size] = {'a', 'b', 'c', 'd', 'e', '\0'};
+ // Should return null terminator.
+ ASSERT_STREQ(call_memrchr(src, '\0', size), "");
+}
+
+TEST(MemRChrTest, CharacterNotWithinStringShouldReturnNullptr) {
+ const size_t size = 4;
+ const unsigned char src[size] = {'1', '2', '3', '?'};
+ // Since 'z' is not within 'characters', should return nullptr.
+ ASSERT_STREQ(call_memrchr(src, 'z', size), nullptr);
+}
+
+TEST(MemRChrTest, CharacterNotWithinSizeShouldReturnNullptr) {
+ const unsigned char src[5] = {'1', '2', '3', '4', '\0'};
+ // Since '4' is not within the first 2 characters, this should return nullptr.
+ const size_t size = 2;
+ ASSERT_STREQ(call_memrchr(src, '4', size), nullptr);
+}
+
+TEST(MemRChrTest, ShouldFindLastOfDuplicates) {
+ size_t size = 12; // 11 characters + null terminator.
+ const char *dups = "abc1def1ghi";
+ // 1 is duplicated in 'dups', but it should find the last copy.
+ ASSERT_STREQ(call_memrchr(dups, '1', size), "1ghi");
+
+ const char *repeated = "XXXXX";
+ size = 6; // 5 characters + null terminator.
+ // Should return the last X with the null terminator.
+ ASSERT_STREQ(call_memrchr(repeated, 'X', size), "X");
+}
+
+TEST(MemRChrTest, EmptyStringShouldOnlyMatchNullTerminator) {
+ const size_t size = 1; // Null terminator.
+ const char *empty_string = "";
+ // Null terminator should match.
+ ASSERT_STREQ(call_memrchr(empty_string, '\0', size), "");
+ // All other characters should not match.
+ ASSERT_STREQ(call_memrchr(empty_string, 'A', size), nullptr);
+ ASSERT_STREQ(call_memrchr(empty_string, '9', size), nullptr);
+ ASSERT_STREQ(call_memrchr(empty_string, '?', size), nullptr);
+}
+
+TEST(MemRChrTest, SignedCharacterFound) {
+ char c = -1;
+ const size_t size = 1;
+ char src[size] = {c};
+ const char *actual = call_memrchr(src, c, size);
+ // Should find the last character 'c'.
+ ASSERT_EQ(actual[0], c);
+}
+
+TEST(MemRChrTest, ZeroLengthShouldReturnNullptr) {
+ const unsigned char src[4] = {'a', 'b', 'c', '\0'};
+ // This will iterate over exactly zero characters, so should return nullptr.
+ ASSERT_STREQ(call_memrchr(src, 'd', 0), nullptr);
+}
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