[libc] Implemented wmempcpy

[uzairnawaz]

Implemented wmempcpy and added tests

[llvmbot]

@llvm/pr-subscribers-libc

Author: Uzair Nawaz (uzairnawaz)

Changes

Implemented wmempcpy and added tests

---

Full diff: https://github.com/llvm/llvm-project/pull/142067.diff

7 Files Affected:

• (modified) libc/config/linux/x86_64/entrypoints.txt (+1)
• (modified) libc/include/wchar.yaml (+8)
• (modified) libc/src/wchar/CMakeLists.txt (+13)
• (added) libc/src/wchar/wmempcpy.cpp (+25)
• (added) libc/src/wchar/wmempcpy.h (+23)
• (modified) libc/test/src/wchar/CMakeLists.txt (+10)
• (added) libc/test/src/wchar/wmempcpy_test.cpp (+44)

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..5f152c394a426 100644
--- a/libc/include/wchar.yaml
+++ b/libc/include/wchar.yaml
@@ -50,3 +50,11 @@ 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);
+}

[michaelrj-google]

this should be gnu since this isn't actually in the c standard.

[michaelrj-google]

you should set at least one byte in dest then check that it isn't modified when size = 0.

[michaelrj-google]

nit: it's good to be consistent with which side has src vs dest. In general I'd recommend putting the thing being tested on the left and the expected result on the right, so in this case dest[n] == src[n].

[michaelrj-google]

LGTM, planning to merge once postsubmit checks are done with the previous change

[michaelrj-google]

Will merge once the conflicts are dealt with