[libc-commits] [libc] f0c0dda - [libc] implement the final macros for stdbit.h support (#84798)

[via libc-commits]

Author: Nick Desaulniers
Date: 2024-03-12T08:39:17-07:00
New Revision: f0c0ddae45ec929d023232d2ff0b75b7f09853c2

URL: https://github.com/llvm/llvm-project/commit/f0c0ddae45ec929d023232d2ff0b75b7f09853c2
DIFF: https://github.com/llvm/llvm-project/commit/f0c0ddae45ec929d023232d2ff0b75b7f09853c2.diff

LOG: [libc] implement the final macros for stdbit.h support (#84798)


Relevant sections of n3096:
- 7.18.1p1
- 7.18.2

Added: 
    

Modified: 
    libc/docs/c23.rst
    libc/docs/stdbit.rst
    libc/include/llvm-libc-macros/stdbit-macros.h
    libc/spec/stdc.td
    libc/test/include/stdbit_test.cpp

Removed: 
    


################################################################################
diff  --git a/libc/docs/c23.rst b/libc/docs/c23.rst
index 24cef8539393df..3f64722bc8e644 100644
--- a/libc/docs/c23.rst
+++ b/libc/docs/c23.rst
@@ -75,7 +75,7 @@ Additions:
   * dfmal
   * fsqrt*
   * dsqrtl
-* stdbit.h (New header)
+* stdbit.h (New header)    |check|
 * stdckdint.h (New header) |check|
 * stddef.h
 

diff  --git a/libc/docs/stdbit.rst b/libc/docs/stdbit.rst
index 9b4974cf1479b1..d42f7938246293 100644
--- a/libc/docs/stdbit.rst
+++ b/libc/docs/stdbit.rst
@@ -110,10 +110,10 @@ Macros
 =========================  =========
 Macro Name                 Available
 =========================  =========
-__STDC_VERSION_STDBIT_H__
-__STDC_ENDIAN_LITTLE__
-__STDC_ENDIAN_BIG__
-__STDC_ENDIAN_NATIVE__
+__STDC_VERSION_STDBIT_H__  |check|
+__STDC_ENDIAN_LITTLE__     |check|
+__STDC_ENDIAN_BIG__        |check|
+__STDC_ENDIAN_NATIVE__     |check|
 stdc_leading_zeros         |check|
 stdc_leading_ones          |check|
 stdc_trailing_zeros        |check|

diff  --git a/libc/include/llvm-libc-macros/stdbit-macros.h b/libc/include/llvm-libc-macros/stdbit-macros.h
index 10c0fac3c8dd86..c5b2f097783440 100644
--- a/libc/include/llvm-libc-macros/stdbit-macros.h
+++ b/libc/include/llvm-libc-macros/stdbit-macros.h
@@ -9,6 +9,11 @@
 #ifndef __LLVM_LIBC_MACROS_STDBIT_MACROS_H
 #define __LLVM_LIBC_MACROS_STDBIT_MACROS_H
 
+#define __STDC_VERSION_STDBIT_H__ 202311L
+#define __STDC_ENDIAN_LITTLE__ __ORDER_LITTLE_ENDIAN__
+#define __STDC_ENDIAN_BIG__ __ORDER_BIG_ENDIAN__
+#define __STDC_ENDIAN_NATIVE__ __BYTE_ORDER__
+
 // TODO(https://github.com/llvm/llvm-project/issues/80509): support _BitInt().
 #ifdef __cplusplus
 inline unsigned stdc_leading_zeros(unsigned char x) {

diff  --git a/libc/spec/stdc.td b/libc/spec/stdc.td
index 1f14fe758130e8..1f9917b1f073e2 100644
--- a/libc/spec/stdc.td
+++ b/libc/spec/stdc.td
@@ -805,6 +805,10 @@ def StdC : StandardSpec<"stdc"> {
   HeaderSpec StdBit = HeaderSpec<
       "stdbit.h",
       [
+        Macro<"__STDC_VERSION_STDBIT_H__">,
+        Macro<"__STDC_ENDIAN_LITTLE__">,
+        Macro<"__STDC_ENDIAN_BIG__">,
+        Macro<"__STDC_ENDIAN_NATIVE__">,
         Macro<"stdc_leading_zeros">,
         Macro<"stdc_leading_ones">,
         Macro<"stdc_trailing_zeros">,

diff  --git a/libc/test/include/stdbit_test.cpp b/libc/test/include/stdbit_test.cpp
index f3227eb86959eb..bee1a19f9c031a 100644
--- a/libc/test/include/stdbit_test.cpp
+++ b/libc/test/include/stdbit_test.cpp
@@ -141,3 +141,20 @@ TEST(LlvmLibcStdbitTest, TypeGenericMacroBitCeil) {
   EXPECT_EQ(stdc_bit_ceil(0UL), 0x6DUL);
   EXPECT_EQ(stdc_bit_ceil(0ULL), 0x6EULL);
 }
+
+TEST(LlvmLibcStdbitTest, VersionMacro) {
+  // 7.18.1p2 an integer constant expression with a value equivalent to 202311L.
+  EXPECT_EQ(__STDC_VERSION_STDBIT_H__, 202311L);
+}
+
+TEST(LlvmLibcStdbitTest, EndianMacros) {
+  // 7.18.2p3 The values of the integer constant expressions for
+  // __STDC_ENDIAN_LITTLE__ and __STDC_ENDIAN_BIG__ are not equal.
+  EXPECT_NE(__STDC_ENDIAN_LITTLE__, __STDC_ENDIAN_BIG__);
+  // The standard does allow for __STDC_ENDIAN_NATIVE__ to be an integer
+  // constant expression with an implementation defined value for non-big or
+  // little endianness environments.  I assert such machines are no longer
+  // relevant.
+  EXPECT_TRUE(__STDC_ENDIAN_NATIVE__ == __STDC_ENDIAN_LITTLE__ ||
+              __STDC_ENDIAN_NATIVE__ == __STDC_ENDIAN_BIG__);
+}