[libc-commits] [libc] [libc] wmemcmp implementation (PR #141880)
via libc-commits
libc-commits at lists.llvm.org
Thu May 29 12:52:21 PDT 2025
https://github.com/sribee8 updated https://github.com/llvm/llvm-project/pull/141880
>From c53acbfbb053c7a38cbc70118abeea791a90eb1a Mon Sep 17 00:00:00 2001
From: Sriya Pratipati <sriyap at google.com>
Date: Wed, 28 May 2025 23:35:55 +0000
Subject: [PATCH 1/4] [libc] wmemcmp implementation
---
libc/config/linux/x86_64/entrypoints.txt | 1 +
libc/include/wchar.yaml | 8 +++++
libc/src/wchar/CMakeLists.txt | 12 +++++++
libc/src/wchar/wmemcmp.cpp | 28 +++++++++++++++++
libc/src/wchar/wmemcmp.h | 22 +++++++++++++
libc/test/src/wchar/CMakeLists.txt | 10 ++++++
libc/test/src/wchar/wmemcmp_test.cpp | 40 ++++++++++++++++++++++++
7 files changed, 121 insertions(+)
create mode 100644 libc/src/wchar/wmemcmp.cpp
create mode 100644 libc/src/wchar/wmemcmp.h
create mode 100644 libc/test/src/wchar/wmemcmp_test.cpp
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 52e746e32a1cd..92fe5d5156acb 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -365,6 +365,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.wchar.wcslen
libc.src.wchar.wctob
libc.src.wchar.wcschr
+ libc.src.wchar.wmemcmp
# sys/uio.h entrypoints
libc.src.sys.uio.writev
diff --git a/libc/include/wchar.yaml b/libc/include/wchar.yaml
index 987bdc0b806dc..0881e2c54492e 100644
--- a/libc/include/wchar.yaml
+++ b/libc/include/wchar.yaml
@@ -34,3 +34,11 @@ functions:
arguments:
- type: const wchar_t *
- type: wchar_t
+ - name: wmemcmp
+ standards:
+ - stdc
+ return_type: int
+ arguments:
+ - type: const wchar_t *
+ - type: const wchar_t *
+ - type: size_t
diff --git a/libc/src/wchar/CMakeLists.txt b/libc/src/wchar/CMakeLists.txt
index 41034cab16d4d..a22e5c0bd8250 100644
--- a/libc/src/wchar/CMakeLists.txt
+++ b/libc/src/wchar/CMakeLists.txt
@@ -44,3 +44,15 @@ add_entrypoint_object(
libc.hdr.wchar_macros
libc.src.__support.wctype_utils
)
+
+add_entrypoint_object(
+ wmemcmp
+ SRCS
+ wmemcmp.cpp
+ HDRS
+ wmemcmp.h
+ DEPENDS
+ libc.hdr.types.size_t
+ libc.hdr.wchar_macros
+ libc.src.__support.wctype_utils
+)
diff --git a/libc/src/wchar/wmemcmp.cpp b/libc/src/wchar/wmemcmp.cpp
new file mode 100644
index 0000000000000..95a342d0295b1
--- /dev/null
+++ b/libc/src/wchar/wmemcmp.cpp
@@ -0,0 +1,28 @@
+//===-- Implementation of wmemcmp ------------------------------------------===//
+//
+// 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/wchar/wmemcmp.h"
+
+#include "hdr/types/size_t.h"
+#include "hdr/types/wchar_t.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(int, wmemcmp,
+ (const wchar_t *s1, const wchar_t *s2, size_t n)) {
+ for (size_t i = 0; i < n; ++s1, ++s2, ++i) {
+ if (*s1 != *s2)
+ return (int)(*s1 - *s2);
+ }
+ // If it reaches the end, all n values must be the same.
+ return 0;
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/wchar/wmemcmp.h b/libc/src/wchar/wmemcmp.h
new file mode 100644
index 0000000000000..3cec26a8871d6
--- /dev/null
+++ b/libc/src/wchar/wmemcmp.h
@@ -0,0 +1,22 @@
+//===-- Implementation header for wmemcmp ----------------------------------===//
+//
+// 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_WCHAR_WMEMCMP_H
+#define LLVM_LIBC_SRC_WCHAR_WMEMCMP_H
+
+#include "hdr/types/size_t.h"
+#include "hdr/types/wchar_t.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+int wmemcmp(const wchar_t *s1, const wchar_t *s2, size_t n);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_WCHAR_WMEMCMP_H
diff --git a/libc/test/src/wchar/CMakeLists.txt b/libc/test/src/wchar/CMakeLists.txt
index 7d64dfeb13b6e..c6aaf49359799 100644
--- a/libc/test/src/wchar/CMakeLists.txt
+++ b/libc/test/src/wchar/CMakeLists.txt
@@ -42,3 +42,13 @@ add_libc_test(
DEPENDS
libc.src.wchar.wcschr
)
+
+add_libc_test(
+ wmemcmp_test
+ SUITE
+ libc_wchar_unittests
+ SRCS
+ wmemcmp_test.cpp
+ DEPENDS
+ libc.src.wchar.wmemcmp
+)
diff --git a/libc/test/src/wchar/wmemcmp_test.cpp b/libc/test/src/wchar/wmemcmp_test.cpp
new file mode 100644
index 0000000000000..a2d45c8d91d23
--- /dev/null
+++ b/libc/test/src/wchar/wmemcmp_test.cpp
@@ -0,0 +1,40 @@
+//===-- Unittests for wmemcmp ----------------------------------------------===//
+//
+// 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 "hdr/types/size_t.h"
+#include "hdr/types/wchar_t.h"
+#include "src/wchar/wmemcmp.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcWMemcmpTest, CmpZeroByte) {
+ // Comparing zero bytes should result in 0.
+ const wchar_t *lhs = L"ab";
+ const wchar_t *rhs = L"yz";
+ EXPECT_EQ(LIBC_NAMESPACE::wmemcmp(lhs, rhs, 0), 0);
+}
+
+TEST(LlvmLibcWMemcmpTest, LhsRhsAreTheSame) {
+ // Comparing strings of equal value should result in 0.
+ const wchar_t *lhs = L"ab";
+ const wchar_t *rhs = L"ab";
+ EXPECT_EQ(LIBC_NAMESPACE::wmemcmp(lhs, rhs, 2), 0);
+}
+
+TEST(LlvmLibcWMemcmpTest, LhsBeforeRhsLexically) {
+ // z after b, should result in a value less than 0.
+ const wchar_t *lhs = L"ab";
+ const wchar_t *rhs = L"az";
+ EXPECT_LT(LIBC_NAMESPACE::wmemcmp(lhs, rhs, 2), 0);
+}
+
+TEST(LlvmLibcWMemcmpTest, LhsAfterRhsLexically) {
+ // z after b, should result in a value greater than 0.
+ const wchar_t *lhs = L"az";
+ const wchar_t *rhs = L"ab";
+ EXPECT_GT(LIBC_NAMESPACE::wmemcmp(lhs, rhs, 2), 0);
+}
>From 873b71681f575175942cca070e694ba5e20da8a3 Mon Sep 17 00:00:00 2001
From: Sriya Pratipati <sriyap at google.com>
Date: Wed, 28 May 2025 23:48:58 +0000
Subject: [PATCH 2/4] Fixed hyphens in first lines
---
libc/src/wchar/wmemcmp.cpp | 2 +-
libc/src/wchar/wmemcmp.h | 2 +-
libc/test/src/wchar/wmemcmp_test.cpp | 2 +-
3 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/libc/src/wchar/wmemcmp.cpp b/libc/src/wchar/wmemcmp.cpp
index 95a342d0295b1..1a98659760a41 100644
--- a/libc/src/wchar/wmemcmp.cpp
+++ b/libc/src/wchar/wmemcmp.cpp
@@ -1,4 +1,4 @@
-//===-- Implementation of wmemcmp ------------------------------------------===//
+//===-- Implementation of wmemcmp -----------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
diff --git a/libc/src/wchar/wmemcmp.h b/libc/src/wchar/wmemcmp.h
index 3cec26a8871d6..51f5fbb8ef53f 100644
--- a/libc/src/wchar/wmemcmp.h
+++ b/libc/src/wchar/wmemcmp.h
@@ -1,4 +1,4 @@
-//===-- Implementation header for wmemcmp ----------------------------------===//
+//===-- Implementation header for wmemcmp ---------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
diff --git a/libc/test/src/wchar/wmemcmp_test.cpp b/libc/test/src/wchar/wmemcmp_test.cpp
index a2d45c8d91d23..1e0d3f3921040 100644
--- a/libc/test/src/wchar/wmemcmp_test.cpp
+++ b/libc/test/src/wchar/wmemcmp_test.cpp
@@ -1,4 +1,4 @@
-//===-- Unittests for wmemcmp ----------------------------------------------===//
+//===-- Unittests for wmemcmp ---------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
>From 4441fce22c46e4bdcb2ae36d7fe1712a10706341 Mon Sep 17 00:00:00 2001
From: Sriya Pratipati <sriyap at google.com>
Date: Wed, 28 May 2025 23:59:02 +0000
Subject: [PATCH 3/4] Fixed part of the implementation and added more tests.
---
libc/src/wchar/wmemcmp.cpp | 6 +++---
libc/test/src/wchar/wmemcmp_test.cpp | 28 ++++++++++++++++++++++++++++
2 files changed, 31 insertions(+), 3 deletions(-)
diff --git a/libc/src/wchar/wmemcmp.cpp b/libc/src/wchar/wmemcmp.cpp
index 1a98659760a41..f2fa361c69798 100644
--- a/libc/src/wchar/wmemcmp.cpp
+++ b/libc/src/wchar/wmemcmp.cpp
@@ -17,9 +17,9 @@ namespace LIBC_NAMESPACE_DECL {
LLVM_LIBC_FUNCTION(int, wmemcmp,
(const wchar_t *s1, const wchar_t *s2, size_t n)) {
- for (size_t i = 0; i < n; ++s1, ++s2, ++i) {
- if (*s1 != *s2)
- return (int)(*s1 - *s2);
+ for (size_t i = 0; i < n; ++i) {
+ if (s1[i] != s2[i])
+ return (int)(s1[i] - s2[i]);
}
// If it reaches the end, all n values must be the same.
return 0;
diff --git a/libc/test/src/wchar/wmemcmp_test.cpp b/libc/test/src/wchar/wmemcmp_test.cpp
index 1e0d3f3921040..942bc9fe4bade 100644
--- a/libc/test/src/wchar/wmemcmp_test.cpp
+++ b/libc/test/src/wchar/wmemcmp_test.cpp
@@ -38,3 +38,31 @@ TEST(LlvmLibcWMemcmpTest, LhsAfterRhsLexically) {
const wchar_t *rhs = L"ab";
EXPECT_GT(LIBC_NAMESPACE::wmemcmp(lhs, rhs, 2), 0);
}
+
+TEST(LlvmLibcWMemcmpTest, CompareToEmpty) {
+ // lhs is nonempty, should result in a value greater than 0.
+ const wchar_t *lhs = L"az";
+ const wchar_t *rhs = L"";
+ EXPECT_GT(LIBC_NAMESPACE::wmemcmp(lhs, rhs, 2), 0);
+}
+
+TEST(LlvmLibcWMemcmpTest, LhsAfterRhsLexicallyLong) {
+ // b after a, should result in a value greater than 0.
+ const wchar_t *lhs = L"aaaaaaaaaaaaab";
+ const wchar_t *rhs = L"aaaaaaaaaaaaaa";
+ EXPECT_GT(LIBC_NAMESPACE::wmemcmp(lhs, rhs, 15), 0);
+}
+
+TEST(LlvmLibcWMemcmpTest, RhsAfterLhsLexicallyLong) {
+ // b after a, should result in a value less than 0.
+ const wchar_t *lhs = L"aaaaaaaaaaaaaa";
+ const wchar_t *rhs = L"aaaaaaaaaaaaab";
+ EXPECT_LT(LIBC_NAMESPACE::wmemcmp(lhs, rhs, 15), 0);
+}
+
+TEST(LlvmLibcWMemcmpTest, LhsRhsAreTheSameLong) {
+ // Comparing strings of equal value should result in 0.
+ const wchar_t *lhs = L"aaaaaaaaaaaaaa";
+ const wchar_t *rhs = L"aaaaaaaaaaaaaa";
+ EXPECT_EQ(LIBC_NAMESPACE::wmemcmp(lhs, rhs, 15), 0);
+}
>From e3f4cfc0a994f832d8e44db79e2d1604458433ce Mon Sep 17 00:00:00 2001
From: Sriya Pratipati <sriyap at google.com>
Date: Thu, 29 May 2025 18:41:26 +0000
Subject: [PATCH 4/4] Modified CompareToEmpty test
---
libc/test/src/wchar/wmemcmp_test.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libc/test/src/wchar/wmemcmp_test.cpp b/libc/test/src/wchar/wmemcmp_test.cpp
index 942bc9fe4bade..536299fd7daf0 100644
--- a/libc/test/src/wchar/wmemcmp_test.cpp
+++ b/libc/test/src/wchar/wmemcmp_test.cpp
@@ -43,7 +43,7 @@ TEST(LlvmLibcWMemcmpTest, CompareToEmpty) {
// lhs is nonempty, should result in a value greater than 0.
const wchar_t *lhs = L"az";
const wchar_t *rhs = L"";
- EXPECT_GT(LIBC_NAMESPACE::wmemcmp(lhs, rhs, 2), 0);
+ EXPECT_GT(LIBC_NAMESPACE::wmemcmp(lhs, rhs, 1), 0);
}
TEST(LlvmLibcWMemcmpTest, LhsAfterRhsLexicallyLong) {
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