[libc-commits] [libc] [libc] Implemented wmempcpy (PR #142067)

Uzair Nawaz via libc-commits libc-commits at lists.llvm.org
Fri May 30 14:10:46 PDT 2025 

https://github.com/uzairnawaz updated https://github.com/llvm/llvm-project/pull/142067

>From 4b3dcdaa3281f7c48283fffaa8d617a574e80a27 Mon Sep 17 00:00:00 2001
From: Uzair Nawaz <uzairnawaz at google.com>
Date: Thu, 29 May 2025 23:54:15 +0000
Subject: [PATCH 1/4] wmempcpy implemented

---
 libc/config/linux/x86_64/entrypoints.txt |  1 +
 libc/include/wchar.yaml                  | 10 ++++++
 libc/src/wchar/CMakeLists.txt            | 13 +++++++
 libc/src/wchar/wmempcpy.cpp              | 25 ++++++++++++++
 libc/src/wchar/wmempcpy.h                | 23 +++++++++++++
 libc/test/src/wchar/CMakeLists.txt       | 10 ++++++
 libc/test/src/wchar/wmempcpy_test.cpp    | 44 ++++++++++++++++++++++++
 7 files changed, 126 insertions(+)
 create mode 100644 libc/src/wchar/wmempcpy.cpp
 create mode 100644 libc/src/wchar/wmempcpy.h
 create mode 100644 libc/test/src/wchar/wmempcpy_test.cpp

diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index de32b17a721dc..b74f84dae54bb 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -367,6 +367,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.wchar.wmemset
     libc.src.wchar.wcschr
     libc.src.wchar.wmemcmp
+    libc.src.wchar.wmempcpy
 
     # sys/uio.h entrypoints
     libc.src.sys.uio.writev
diff --git a/libc/include/wchar.yaml b/libc/include/wchar.yaml
index a1178ba96bd45..013d53a6cb82b 100644
--- a/libc/include/wchar.yaml
+++ b/libc/include/wchar.yaml
@@ -50,3 +50,13 @@ functions:
       - type: const wchar_t *
       - type: const wchar_t *
       - type: size_t
+  - name: wmempcpy
+    standards:
+      - stdc
+    return_type: wchar_t * 
+    arguments: 
+      - type: wchar_t *
+      - type: const wchar_t *
+      - type: size_t
+  
+
diff --git a/libc/src/wchar/CMakeLists.txt b/libc/src/wchar/CMakeLists.txt
index 43f571fed91af..a194b78abbb82 100644
--- a/libc/src/wchar/CMakeLists.txt
+++ b/libc/src/wchar/CMakeLists.txt
@@ -68,3 +68,16 @@ add_entrypoint_object(
     libc.hdr.wchar_macros
     libc.src.__support.wctype_utils
 )
+
+add_entrypoint_object(
+  wmempcpy
+  SRCS
+    wmempcpy.cpp
+  HDRS
+    wmempcpy.h
+  DEPENDS
+    libc.hdr.types.size_t
+    libc.hdr.wchar_macros
+    libc.src.__support.wctype_utils
+    libc.src.string.memory_utils.inline_memcpy
+)
diff --git a/libc/src/wchar/wmempcpy.cpp b/libc/src/wchar/wmempcpy.cpp
new file mode 100644
index 0000000000000..d8b89c0a88d05
--- /dev/null
+++ b/libc/src/wchar/wmempcpy.cpp
@@ -0,0 +1,25 @@
+//===-- Implementation of wmempcpy ----------------------------------------===//
+//
+// 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/wmempcpy.h"
+
+#include "hdr/types/size_t.h"
+#include "hdr/types/wchar_t.h"
+#include "src/__support/common.h"
+#include "src/string/memory_utils/inline_memcpy.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(wchar_t *, wmempcpy,
+                   (wchar_t *__restrict to, const wchar_t *__restrict from,
+                    size_t size)) {
+  inline_memcpy(to, from, size * sizeof(wchar_t));
+  return reinterpret_cast<wchar_t *>(to) + size;
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/wchar/wmempcpy.h b/libc/src/wchar/wmempcpy.h
new file mode 100644
index 0000000000000..580674b1be807
--- /dev/null
+++ b/libc/src/wchar/wmempcpy.h
@@ -0,0 +1,23 @@
+//===-- Implementation header for wmempcpy---------------------------------===//
+//
+// 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_WMEMPCPY_H
+#define LLVM_LIBC_SRC_WCHAR_WMEMPCPY_H
+
+#include "hdr/types/size_t.h"
+#include "hdr/types/wchar_t.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+wchar_t *wmempcpy(wchar_t *__restrict from, const wchar_t *__restrict s2,
+                  size_t n);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_WCHAR_WMEMPCPY_H
diff --git a/libc/test/src/wchar/CMakeLists.txt b/libc/test/src/wchar/CMakeLists.txt
index 05eeef0e92733..9cab62c66f54c 100644
--- a/libc/test/src/wchar/CMakeLists.txt
+++ b/libc/test/src/wchar/CMakeLists.txt
@@ -64,3 +64,13 @@ add_libc_test(
   DEPENDS
     libc.src.wchar.wmemcmp
 )
+
+add_libc_test(
+  wmempcpy_test
+  SUITE
+    libc_wchar_unittests
+  SRCS
+    wmempcpy_test.cpp
+  DEPENDS
+    libc.src.wchar.wmempcpy
+)
diff --git a/libc/test/src/wchar/wmempcpy_test.cpp b/libc/test/src/wchar/wmempcpy_test.cpp
new file mode 100644
index 0000000000000..2b30242b657b3
--- /dev/null
+++ b/libc/test/src/wchar/wmempcpy_test.cpp
@@ -0,0 +1,44 @@
+//===-- Unittests for wmempcpy --------------------------------------------===//
+//
+// 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/wmempcpy.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcWMempcpyTest, Simple) {
+  const wchar_t *src = L"12345";
+  wchar_t dest[10] = {};
+  void *result = LIBC_NAMESPACE::wmempcpy(dest, src, 6);
+  ASSERT_EQ(static_cast<wchar_t *>(result), dest + 6);
+
+  ASSERT_TRUE(src[0] == dest[0]);
+  ASSERT_TRUE(src[1] == dest[1]);
+  ASSERT_TRUE(src[2] == dest[2]);
+  ASSERT_TRUE(src[3] == dest[3]);
+  ASSERT_TRUE(src[4] == dest[4]);
+  ASSERT_TRUE(src[5] == dest[5]);
+}
+
+TEST(LlvmLibcWmempcpyTest, ZeroCount) {
+  const wchar_t *src = L"12345";
+  wchar_t dest[10];
+  void *result = LIBC_NAMESPACE::wmempcpy(dest, src, 0);
+  ASSERT_EQ(static_cast<wchar_t *>(result), dest);
+}
+
+TEST(LlvmLibcWMempcpyTest, BoundaryCheck) {
+  const wchar_t *src = L"12345";
+  wchar_t dest[4] = {};
+  void *result = LIBC_NAMESPACE::wmempcpy(dest + 1, src + 1, 2);
+
+  ASSERT_TRUE(dest[0] == 0);
+  ASSERT_TRUE(dest[1] == src[1]);
+  ASSERT_TRUE(dest[2] == src[2]);
+  ASSERT_TRUE(dest[3] == 0);
+
+  ASSERT_EQ(static_cast<wchar_t *>(result), dest + 3);
+}

>From bf6863b33c266a358645311c6200de98bd4351fa Mon Sep 17 00:00:00 2001
From: Uzair Nawaz <uzairnawaz at google.com>
Date: Thu, 29 May 2025 23:57:22 +0000
Subject: [PATCH 2/4] removed extra lines

---
 libc/include/wchar.yaml | 2 --
 1 file changed, 2 deletions(-)

diff --git a/libc/include/wchar.yaml b/libc/include/wchar.yaml
index 013d53a6cb82b..5f152c394a426 100644
--- a/libc/include/wchar.yaml
+++ b/libc/include/wchar.yaml
@@ -58,5 +58,3 @@ functions:
       - type: wchar_t *
       - type: const wchar_t *
       - type: size_t
-  
-

>From ab48745e8e68884a16180ca62a9ad0439fb1c128 Mon Sep 17 00:00:00 2001
From: Uzair Nawaz <uzairnawaz at google.com>
Date: Fri, 30 May 2025 17:55:20 +0000
Subject: [PATCH 3/4] updated standard in wchar.yaml; improved test for 0 count

---
 libc/include/wchar.yaml               | 2 +-
 libc/test/src/wchar/wmempcpy_test.cpp | 8 +++++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/libc/include/wchar.yaml b/libc/include/wchar.yaml
index 5f152c394a426..4460cfcb7d441 100644
--- a/libc/include/wchar.yaml
+++ b/libc/include/wchar.yaml
@@ -52,7 +52,7 @@ functions:
       - type: size_t
   - name: wmempcpy
     standards:
-      - stdc
+      - gnu
     return_type: wchar_t * 
     arguments: 
       - type: wchar_t *
diff --git a/libc/test/src/wchar/wmempcpy_test.cpp b/libc/test/src/wchar/wmempcpy_test.cpp
index 2b30242b657b3..365ab221503d1 100644
--- a/libc/test/src/wchar/wmempcpy_test.cpp
+++ b/libc/test/src/wchar/wmempcpy_test.cpp
@@ -25,9 +25,15 @@ TEST(LlvmLibcWMempcpyTest, Simple) {
 
 TEST(LlvmLibcWmempcpyTest, ZeroCount) {
   const wchar_t *src = L"12345";
-  wchar_t dest[10];
+  wchar_t dest[5] = {};
   void *result = LIBC_NAMESPACE::wmempcpy(dest, src, 0);
   ASSERT_EQ(static_cast<wchar_t *>(result), dest);
+
+  ASSERT_TRUE(dest[0] == 0);
+  ASSERT_TRUE(dest[1] == 0);
+  ASSERT_TRUE(dest[2] == 0);
+  ASSERT_TRUE(dest[3] == 0);
+  ASSERT_TRUE(dest[4] == 0);
 }
 
 TEST(LlvmLibcWMempcpyTest, BoundaryCheck) {

>From d2abc42f95f8fd8cfa6ec9a227688f54be37a166 Mon Sep 17 00:00:00 2001
From: Uzair Nawaz <uzairnawaz at google.com>
Date: Fri, 30 May 2025 21:10:13 +0000
Subject: [PATCH 4/4] consistent order of dest/src in test

---
 libc/test/src/wchar/wmempcpy_test.cpp | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/libc/test/src/wchar/wmempcpy_test.cpp b/libc/test/src/wchar/wmempcpy_test.cpp
index 365ab221503d1..000e4b3899090 100644
--- a/libc/test/src/wchar/wmempcpy_test.cpp
+++ b/libc/test/src/wchar/wmempcpy_test.cpp
@@ -15,12 +15,12 @@ TEST(LlvmLibcWMempcpyTest, Simple) {
   void *result = LIBC_NAMESPACE::wmempcpy(dest, src, 6);
   ASSERT_EQ(static_cast<wchar_t *>(result), dest + 6);
 
-  ASSERT_TRUE(src[0] == dest[0]);
-  ASSERT_TRUE(src[1] == dest[1]);
-  ASSERT_TRUE(src[2] == dest[2]);
-  ASSERT_TRUE(src[3] == dest[3]);
-  ASSERT_TRUE(src[4] == dest[4]);
-  ASSERT_TRUE(src[5] == dest[5]);
+  ASSERT_TRUE(dest[0] == src[0]);
+  ASSERT_TRUE(dest[1] == src[1]);
+  ASSERT_TRUE(dest[2] == src[2]);
+  ASSERT_TRUE(dest[3] == src[3]);
+  ASSERT_TRUE(dest[4] == src[4]);
+  ASSERT_TRUE(dest[5] == src[5]);
 }
 
 TEST(LlvmLibcWmempcpyTest, ZeroCount) {

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