[libc-commits] [libc] [libc] Add the `<endian.h>` header. (PR #125168)

[via libc-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libc

Author: None (c8ef)

<details>
<summary>Changes</summary>

Closes [#<!-- -->124631](https://github.com/llvm/llvm-project/issues/124631).
ref: https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/endian.h.html

This patch adds the implementation of `endian.h`, which includes the header itself and three related macros. These macros in the header rely on the compiler preprocessor, similar to how https://github.com/llvm/llvm-project/blob/main/libc/src/__support/endian_internal.h does. Hopefully this will meet the requirements for compiling llvm with llvm-libc.

---
Full diff: https://github.com/llvm/llvm-project/pull/125168.diff


7 Files Affected:

- (modified) libc/config/linux/aarch64/headers.txt (+1) 
- (modified) libc/config/linux/x86_64/headers.txt (+1) 
- (modified) libc/include/CMakeLists.txt (+9) 
- (added) libc/include/endian.h.def (+17) 
- (added) libc/include/endian.yaml (+9) 
- (modified) libc/include/llvm-libc-macros/CMakeLists.txt (+6) 
- (added) libc/include/llvm-libc-macros/endian-macros.h (+16) 


``````````diff
diff --git a/libc/config/linux/aarch64/headers.txt b/libc/config/linux/aarch64/headers.txt
index 05f15a0e4e5cbb..7ff55899805508 100644
--- a/libc/config/linux/aarch64/headers.txt
+++ b/libc/config/linux/aarch64/headers.txt
@@ -4,6 +4,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.ctype
     libc.include.dlfcn
     libc.include.elf
+    libc.include.endian
     libc.include.errno
     libc.include.features
     libc.include.fenv
diff --git a/libc/config/linux/x86_64/headers.txt b/libc/config/linux/x86_64/headers.txt
index 8750100302ea7e..fe1fd596960dd3 100644
--- a/libc/config/linux/x86_64/headers.txt
+++ b/libc/config/linux/x86_64/headers.txt
@@ -5,6 +5,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.dirent
     libc.include.dlfcn
     libc.include.elf
+    libc.include.endian
     libc.include.errno
     libc.include.fcntl
     libc.include.features
diff --git a/libc/include/CMakeLists.txt b/libc/include/CMakeLists.txt
index e5ceea360d3965..96d715cde9de9d 100644
--- a/libc/include/CMakeLists.txt
+++ b/libc/include/CMakeLists.txt
@@ -73,6 +73,15 @@ add_header_macro(
     .llvm_libc_common_h
 )
 
+add_header_macro(
+  endian
+  ../libc/include/endian.yaml
+  endian.h
+  DEPENDS
+    .llvm-libc-macros.endian_macros
+    .llvm_libc_common_h
+)
+
 add_header_macro(
   features
   ../libc/include/features.yaml
diff --git a/libc/include/endian.h.def b/libc/include/endian.h.def
new file mode 100644
index 00000000000000..8448d93a86acc3
--- /dev/null
+++ b/libc/include/endian.h.def
@@ -0,0 +1,17 @@
+//===-- System V header endian.h ------------------------------------------===//
+//
+// 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_ENDIAN_H
+#define LLVM_LIBC_ENDIAN_H
+
+#include "__llvm-libc-common.h"
+#include "llvm-libc-macros/endian-macros.h"
+
+%%public_api()
+
+#endif // LLVM_LIBC_ENDIAN_H
diff --git a/libc/include/endian.yaml b/libc/include/endian.yaml
new file mode 100644
index 00000000000000..6497f897b63933
--- /dev/null
+++ b/libc/include/endian.yaml
@@ -0,0 +1,9 @@
+header: endian.h
+header_template: endian.h.def
+standards:
+  - POSIX
+macros: []
+types: []
+enums: []
+objects: []
+functions: []
diff --git a/libc/include/llvm-libc-macros/CMakeLists.txt b/libc/include/llvm-libc-macros/CMakeLists.txt
index 9d5d9f65442889..d165ada6612c84 100644
--- a/libc/include/llvm-libc-macros/CMakeLists.txt
+++ b/libc/include/llvm-libc-macros/CMakeLists.txt
@@ -310,6 +310,12 @@ add_macro_header(
     elf-macros.h
 )
 
+add_macro_header(
+  endian_macros
+  HDR
+    endian-macros.h
+)
+
 add_macro_header(
   locale_macros
   HDR
diff --git a/libc/include/llvm-libc-macros/endian-macros.h b/libc/include/llvm-libc-macros/endian-macros.h
new file mode 100644
index 00000000000000..94e1d60f8ff404
--- /dev/null
+++ b/libc/include/llvm-libc-macros/endian-macros.h
@@ -0,0 +1,16 @@
+//===-- Definition of macros from endian.h --------------------------------===//
+//
+// 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_MACROS_ENDIAN_MACROS_H
+#define LLVM_LIBC_MACROS_ENDIAN_MACROS_H
+
+#define LITTLE_ENDIAN __ORDER_LITTLE_ENDIAN__
+#define BIG_ENDIAN __ORDER_BIG_ENDIAN__
+#define BYTE_ORDER __BYTE_ORDER__
+
+#endif // LLVM_LIBC_MACROS_ENDIAN_MACROS_H

``````````

</details>


https://github.com/llvm/llvm-project/pull/125168