[libc] Implemented wmemmove #142245

uzairnawaz · 2025-05-31T00:23:50Z

Implemented wmemmove and added tests

llvmbot · 2025-05-31T00:24:25Z

@llvm/pr-subscribers-libc

Author: Uzair Nawaz (uzairnawaz)

Changes

Implemented wmemmove and added tests

Full diff: https://github.com/llvm/llvm-project/pull/142245.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/wmemmove.cpp (+28)
(added) libc/src/wchar/wmemmove.h (+22)
(modified) libc/test/src/wchar/CMakeLists.txt (+10)
(added) libc/test/src/wchar/wmemmove_test.cpp (+111)

diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 7ddeb4d31b466..ffedf8e088fe5 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -364,6 +364,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.wchar.btowc
     libc.src.wchar.wcslen
     libc.src.wchar.wctob
+    libc.src.wchar.wmemmove
     libc.src.wchar.wmemset
     libc.src.wchar.wcschr
     libc.src.wchar.wcspbrk
diff --git a/libc/include/wchar.yaml b/libc/include/wchar.yaml
index bd9105f69222c..5117e795d35ea 100644
--- a/libc/include/wchar.yaml
+++ b/libc/include/wchar.yaml
@@ -72,3 +72,11 @@ functions:
       - type: __restricted wchar_t *
       - type: const __ restricted wchar_t *
       - type: size_t
+  - name: wmemmove
+    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 9db121762348b..6d839317fb8d8 100644
--- a/libc/src/wchar/CMakeLists.txt
+++ b/libc/src/wchar/CMakeLists.txt
@@ -104,3 +104,16 @@ add_entrypoint_object(
     libc.hdr.wchar_macros
     libc.src.__support.wctype_utils
 )
+
+add_entrypoint_object(
+  wmemmove
+  SRCS
+    wmemmove.cpp
+  HDRS
+    wmemmove.h
+  DEPENDS
+    libc.hdr.types.size_t
+    libc.hdr.wchar_macros
+    libc.src.__support.wctype_utils
+    libc.src.__support.macros.null_check
+)
diff --git a/libc/src/wchar/wmemmove.cpp b/libc/src/wchar/wmemmove.cpp
new file mode 100644
index 0000000000000..2b7cf21f52667
--- /dev/null
+++ b/libc/src/wchar/wmemmove.cpp
@@ -0,0 +1,28 @@
+//===-- Implementation of wmemmove ----------------------------------------===//
+//
+// 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/wmemmove.h"
+
+#include "hdr/types/size_t.h"
+#include "hdr/types/wchar_t.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/null_check.h"
+#include "src/string/memory_utils/inline_memmove.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(wchar_t *, wmemmove,
+                   (wchar_t *dest, const wchar_t *src, size_t n)) {
+  LIBC_CRASH_ON_NULLPTR(dest);
+  LIBC_CRASH_ON_NULLPTR(src);
+
+  inline_memmove(dest, src, n * sizeof(wchar_t));
+  return dest;
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/wchar/wmemmove.h b/libc/src/wchar/wmemmove.h
new file mode 100644
index 0000000000000..b4c31ac7b397c
--- /dev/null
+++ b/libc/src/wchar/wmemmove.h
@@ -0,0 +1,22 @@
+//===-- Implementation header for wmemmove --------------------------------===//
+//
+// 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_WMEMMOVE_H
+#define LLVM_LIBC_SRC_WCHAR_WMEMMOVE_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 *wmemmove(wchar_t *dest, const wchar_t *src, size_t n);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_WCHAR_WMEMMOVE_H
diff --git a/libc/test/src/wchar/CMakeLists.txt b/libc/test/src/wchar/CMakeLists.txt
index 9bc230e0bddf3..afe283475be69 100644
--- a/libc/test/src/wchar/CMakeLists.txt
+++ b/libc/test/src/wchar/CMakeLists.txt
@@ -94,3 +94,13 @@ add_libc_test(
   DEPENDS
     libc.src.wchar.wmemcpy
 )
+
+add_libc_test(
+  wmemmove_test
+  SUITE
+    libc_wchar_unittests
+  SRCS
+    wmemmove_test.cpp
+  DEPENDS
+    libc.src.wchar.wmemmove
+)
diff --git a/libc/test/src/wchar/wmemmove_test.cpp b/libc/test/src/wchar/wmemmove_test.cpp
new file mode 100644
index 0000000000000..d23aa0f0b3af1
--- /dev/null
+++ b/libc/test/src/wchar/wmemmove_test.cpp
@@ -0,0 +1,111 @@
+//===-- Unittests for wmemmove --------------------------------------------===//
+//
+// 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/wmemmove.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcWMemmoveTest, MoveZeroByte) {
+  wchar_t buffer[] = {L'a', L'b', L'y', L'z'};
+
+  wchar_t *ret = LIBC_NAMESPACE::wmemmove(buffer, buffer + 2, 0);
+  EXPECT_EQ(ret, buffer);
+
+  const wchar_t expected[] = {L'a', L'b', L'y', L'z'};
+  EXPECT_TRUE(buffer[0] == expected[0]);
+  EXPECT_TRUE(buffer[1] == expected[1]);
+  EXPECT_TRUE(buffer[2] == expected[2]);
+  EXPECT_TRUE(buffer[3] == expected[3]);
+}
+
+TEST(LlvmLibcWMemmoveTest, DstAndSrcPointToSameAddress) {
+  wchar_t buffer[] = {L'a', L'b'};
+
+  wchar_t *ret = LIBC_NAMESPACE::wmemmove(buffer, buffer, 1);
+  EXPECT_EQ(ret, buffer);
+
+  const wchar_t expected[] = {L'a', L'b'};
+  EXPECT_TRUE(buffer[0] == expected[0]);
+  EXPECT_TRUE(buffer[1] == expected[1]);
+}
+
+TEST(LlvmLibcWMemmoveTest, DstStartsBeforeSrc) {
+  // Set boundary at beginning and end for not overstepping when
+  // copy forward or backward.
+  wchar_t buffer[] = {L'z', L'a', L'b', L'c', L'z'};
+
+  wchar_t *dst = buffer + 1;
+  wchar_t *ret = LIBC_NAMESPACE::wmemmove(dst, buffer + 2, 2);
+  EXPECT_EQ(ret, dst);
+
+  const wchar_t expected[] = {L'z', L'b', L'c', L'c', L'z'};
+  EXPECT_TRUE(buffer[0] == expected[0]);
+  EXPECT_TRUE(buffer[1] == expected[1]);
+  EXPECT_TRUE(buffer[2] == expected[2]);
+  EXPECT_TRUE(buffer[3] == expected[3]);
+  EXPECT_TRUE(buffer[4] == expected[4]);
+}
+
+TEST(LlvmLibcWMemmoveTest, DstStartsAfterSrc) {
+  wchar_t buffer[] = {L'z', L'a', L'b', L'c', L'z'};
+
+  wchar_t *dst = buffer + 2;
+  wchar_t *ret = LIBC_NAMESPACE::wmemmove(dst, buffer + 1, 2);
+  EXPECT_EQ(ret, dst);
+
+  const wchar_t expected[] = {L'z', L'a', L'a', L'b', L'z'};
+  EXPECT_TRUE(buffer[0] == expected[0]);
+  EXPECT_TRUE(buffer[1] == expected[1]);
+  EXPECT_TRUE(buffer[2] == expected[2]);
+  EXPECT_TRUE(buffer[3] == expected[3]);
+  EXPECT_TRUE(buffer[4] == expected[4]);
+}
+
+// e.g. `Dst` follow `src`.
+// str: [abcdefghij]
+//      [__src_____]
+//      [_____Dst__]
+TEST(LlvmLibcWMemmoveTest, SrcFollowDst) {
+  wchar_t buffer[] = {L'z', L'a', L'b', L'z'};
+
+  wchar_t *dst = buffer + 1;
+  wchar_t *ret = LIBC_NAMESPACE::wmemmove(dst, buffer + 2, 1);
+  EXPECT_EQ(ret, dst);
+
+  const char expected[] = {L'z', L'b', L'b', L'z'};
+  EXPECT_TRUE(buffer[0] == expected[0]);
+  EXPECT_TRUE(buffer[1] == expected[1]);
+  EXPECT_TRUE(buffer[2] == expected[2]);
+  EXPECT_TRUE(buffer[3] == expected[3]);
+}
+
+TEST(LlvmLibcWMemmoveTest, DstFollowSrc) {
+  wchar_t buffer[] = {L'z', L'a', L'b', L'z'};
+
+  wchar_t *dst = buffer + 2;
+  wchar_t *ret = LIBC_NAMESPACE::wmemmove(dst, buffer + 1, 1);
+  EXPECT_EQ(ret, dst);
+
+  const char expected[] = {L'z', L'a', L'a', L'z'};
+  EXPECT_TRUE(buffer[0] == expected[0]);
+  EXPECT_TRUE(buffer[1] == expected[1]);
+  EXPECT_TRUE(buffer[2] == expected[2]);
+  EXPECT_TRUE(buffer[3] == expected[3]);
+}
+
+#if defined(LIBC_ADD_NULL_CHECKS) && !defined(LIBC_HAS_SANITIZER)
+TEST(LlvmLibcWMemmoveTest, NullptrCrash) {
+  wchar_t buffer[] = {L'a', L'b'};
+  // Passing in a nullptr should crash the program.
+  EXPECT_DEATH([&buffer] { LIBC_NAMESPACE::wmemmove(buffer, nullptr, 2); },
+               WITH_SIGNAL(-1));
+  EXPECT_DEATH([&buffer] { LIBC_NAMESPACE::wmemmove(nullptr, buffer, 2); },
+               WITH_SIGNAL(-1));
+}
+#endif // LIBC_HAS_ADDRESS_SANITIZER

github-actions · 2025-05-31T00:26:12Z

✅ With the latest revision this PR passed the C/C++ code formatter.

michaelrj-google

overall LGTM with a build fix

michaelrj-google · 2025-06-02T18:10:50Z

libc/src/wchar/CMakeLists.txt

+  DEPENDS
+    libc.hdr.types.size_t
+    libc.hdr.wchar_macros
+    libc.src.__support.wctype_utils


this function uses inline_memmove and not wctype_utils, need to correct the dependency here.

michaelrj-google

LGTM

michaelrj-google · 2025-06-10T16:27:29Z

libc/src/wchar/wmemmove.cpp

+  LIBC_CRASH_ON_NULLPTR(dest);
+  LIBC_CRASH_ON_NULLPTR(src);
+
+  inline_memmove(dest, src, n * sizeof(wchar_t));


For the memory functions we're moving away from calling the internal ones and towards using the builtins. For that reason this should be __builtin_memmove

Implemented wmemmove and added tests

uzairnawaz added 3 commits May 31, 2025 00:11

implemented wmemmove

e4b5c76

fix death testcase

8119ac2

style

2e8a5c8

llvmbot added the libc label May 31, 2025

format

0dc2431

michaelrj-google reviewed Jun 2, 2025

View reviewed changes

uzairnawaz added 2 commits June 2, 2025 18:22

fixed build file

acc65a1

Merge branch 'main' into wmemmove

e652fd9

michaelrj-google approved these changes Jun 2, 2025

View reviewed changes

uzairnawaz added 3 commits June 2, 2025 22:45

Merge branch 'main' into wmemmove

3ed9728

Merge branch 'main' into wmemmove

da02ea4

Merge branch 'main' into wmemmove

67ea997

michaelrj-google reviewed Jun 10, 2025

View reviewed changes

Switched to __builtin_memmove

542e709

uzairnawaz merged commit b184672 into llvm:main Jun 13, 2025
13 checks passed

tomtor pushed a commit to tomtor/llvm-project that referenced this pull request Jun 14, 2025

[libc] Implemented wmemmove (llvm#142245)

1da26c4

Implemented wmemmove and added tests

akuhlens pushed a commit to akuhlens/llvm-project that referenced this pull request Jun 24, 2025

[libc] Implemented wmemmove (llvm#142245)

354bae3

Implemented wmemmove and added tests

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