[libc] Remove obsolete LIBC_HAS_BUILTIN macro

libc/docs/dev/code_style.rst

@@ -55,7 +55,7 @@ We define two kinds of macros:
    * ``src/__support/macros/config.h`` - Important compiler and platform
      features. Such macros can be used to produce portable code by
      parameterizing compilation based on the presence or lack of a given
-     feature. e.g., ``LIBC_HAS_BUILTIN``
+     feature. e.g., ``LIBC_HAS_FEATURE``
    * ``src/__support/macros/attributes.h`` - Attributes for functions, types,
      and variables. e.g., ``LIBC_UNUSED``
    * ``src/__support/macros/optimization.h`` - Portable macros for performance

libc/src/__support/CPP/CMakeLists.txt

@@ -18,7 +18,6 @@ add_header_library(
     .limits
     .type_traits
     libc.src.__support.macros.attributes
-    libc.src.__support.macros.config
     libc.src.__support.macros.sanitizer
 )
 
@@ -157,7 +156,6 @@ add_header_library(
   DEPENDS
     libc.include.llvm-libc-macros.stdfix_macros
     libc.src.__support.macros.attributes
-    libc.src.__support.macros.config
     libc.src.__support.macros.properties.types
 )
 

libc/src/__support/CPP/atomic.h

@@ -71,10 +71,11 @@ template <typename T> struct Atomic {
 
   T load(MemoryOrder mem_ord = MemoryOrder::SEQ_CST,
          [[maybe_unused]] MemoryScope mem_scope = MemoryScope::DEVICE) {
-    if constexpr (LIBC_HAS_BUILTIN(__scoped_atomic_load_n))
-      return __scoped_atomic_load_n(&val, int(mem_ord), (int)(mem_scope));
-    else
-      return __atomic_load_n(&val, int(mem_ord));
+#if __has_builtin(__scoped_atomic_load_n)
+    return __scoped_atomic_load_n(&val, int(mem_ord), (int)(mem_scope));
+#else
+    return __atomic_load_n(&val, int(mem_ord));
+#endif
   }
 
   // Atomic store.
@@ -85,10 +86,11 @@ template <typename T> struct Atomic {
 
   void store(T rhs, MemoryOrder mem_ord = MemoryOrder::SEQ_CST,
              [[maybe_unused]] MemoryScope mem_scope = MemoryScope::DEVICE) {
-    if constexpr (LIBC_HAS_BUILTIN(__scoped_atomic_store_n))
-      __scoped_atomic_store_n(&val, rhs, int(mem_ord), (int)(mem_scope));
-    else
-      __atomic_store_n(&val, rhs, int(mem_ord));
+#if __has_builtin(__scoped_atomic_store_n)
+    __scoped_atomic_store_n(&val, rhs, int(mem_ord), (int)(mem_scope));
+#else
+    __atomic_store_n(&val, rhs, int(mem_ord));
+#endif
   }
 
   // Atomic compare exchange
@@ -101,47 +103,51 @@ template <typename T> struct Atomic {
 
   T exchange(T desired, MemoryOrder mem_ord = MemoryOrder::SEQ_CST,
              [[maybe_unused]] MemoryScope mem_scope = MemoryScope::DEVICE) {
-    if constexpr (LIBC_HAS_BUILTIN(__scoped_atomic_exchange_n))
-      return __scoped_atomic_exchange_n(&val, desired, int(mem_ord),
-                                        (int)(mem_scope));
-    else
-      return __atomic_exchange_n(&val, desired, int(mem_ord));
+#if __has_builtin(__scoped_atomic_exchange_n)
+    return __scoped_atomic_exchange_n(&val, desired, int(mem_ord),
+                                      (int)(mem_scope));
+#else
+    return __atomic_exchange_n(&val, desired, int(mem_ord));
+#endif
   }
 
   T fetch_add(T increment, MemoryOrder mem_ord = MemoryOrder::SEQ_CST,
               [[maybe_unused]] MemoryScope mem_scope = MemoryScope::DEVICE) {
-    if constexpr (LIBC_HAS_BUILTIN(__scoped_atomic_fetch_add))
-      return __scoped_atomic_fetch_add(&val, increment, int(mem_ord),
-                                       (int)(mem_scope));
-    else
-      return __atomic_fetch_add(&val, increment, int(mem_ord));
+#if __has_builtin(__scoped_atomic_fetch_add)
+    return __scoped_atomic_fetch_add(&val, increment, int(mem_ord),
+                                     (int)(mem_scope));
+#else
+    return __atomic_fetch_add(&val, increment, int(mem_ord));
+#endif
   }
 
   T fetch_or(T mask, MemoryOrder mem_ord = MemoryOrder::SEQ_CST,
              [[maybe_unused]] MemoryScope mem_scope = MemoryScope::DEVICE) {
-    if constexpr (LIBC_HAS_BUILTIN(__scoped_atomic_fetch_or))
-      return __scoped_atomic_fetch_or(&val, mask, int(mem_ord),
-                                      (int)(mem_scope));
-    else
-      return __atomic_fetch_or(&val, mask, int(mem_ord));
+#if __has_builtin(__scoped_atomic_fetch_or)
+    return __scoped_atomic_fetch_or(&val, mask, int(mem_ord), (int)(mem_scope));
+#else
+    return __atomic_fetch_or(&val, mask, int(mem_ord));
+#endif
   }
 
   T fetch_and(T mask, MemoryOrder mem_ord = MemoryOrder::SEQ_CST,
               [[maybe_unused]] MemoryScope mem_scope = MemoryScope::DEVICE) {
-    if constexpr (LIBC_HAS_BUILTIN(__scoped_atomic_fetch_and))
-      return __scoped_atomic_fetch_and(&val, mask, int(mem_ord),
-                                       (int)(mem_scope));
-    else
-      return __atomic_fetch_and(&val, mask, int(mem_ord));
+#if __has_builtin(__scoped_atomic_fetch_and)
+    return __scoped_atomic_fetch_and(&val, mask, int(mem_ord),
+                                     (int)(mem_scope));
+#else
+    return __atomic_fetch_and(&val, mask, int(mem_ord));
+#endif
   }
 
   T fetch_sub(T decrement, MemoryOrder mem_ord = MemoryOrder::SEQ_CST,
               [[maybe_unused]] MemoryScope mem_scope = MemoryScope::DEVICE) {
-    if constexpr (LIBC_HAS_BUILTIN(__scoped_atomic_fetch_sub))
-      return __scoped_atomic_fetch_sub(&val, decrement, int(mem_ord),
-                                       (int)(mem_scope));
-    else
-      return __atomic_fetch_sub(&val, decrement, int(mem_ord));
+#if __has_builtin(__scoped_atomic_fetch_sub)
+    return __scoped_atomic_fetch_sub(&val, decrement, int(mem_ord),
+                                     (int)(mem_scope));
+#else
+    return __atomic_fetch_sub(&val, decrement, int(mem_ord));
+#endif
   }
 
   // Set the value without using an atomic operation. This is useful
@@ -166,7 +172,7 @@ LIBC_INLINE void atomic_thread_fence([[maybe_unused]] MemoryOrder mem_ord) {
 // except no instructions for memory ordering are issued. Only reordering of
 // the instructions by the compiler is suppressed as order instructs.
 LIBC_INLINE void atomic_signal_fence([[maybe_unused]] MemoryOrder mem_ord) {
-#if LIBC_HAS_BUILTIN(__atomic_signal_fence)
+#if __has_builtin(__atomic_signal_fence)
   __atomic_signal_fence(static_cast<int>(mem_ord));
 #else
   // if the builtin is not ready, use asm as a full compiler barrier.

libc/src/__support/CPP/bit.h

@@ -14,14 +14,13 @@
 #include "src/__support/CPP/limits.h" // numeric_limits
 #include "src/__support/CPP/type_traits.h"
 #include "src/__support/macros/attributes.h"
-#include "src/__support/macros/config.h" // LIBC_HAS_BUILTIN
 #include "src/__support/macros/sanitizer.h"
 
 #include <stdint.h>
 
 namespace LIBC_NAMESPACE::cpp {
 
-#if LIBC_HAS_BUILTIN(__builtin_memcpy_inline)
+#if __has_builtin(__builtin_memcpy_inline)
 #define LLVM_LIBC_HAS_BUILTIN_MEMCPY_INLINE
 #endif
 
@@ -36,20 +35,20 @@ LIBC_INLINE constexpr cpp::enable_if_t<
     To>
 bit_cast(const From &from) {
   MSAN_UNPOISON(&from, sizeof(From));
-#if LIBC_HAS_BUILTIN(__builtin_bit_cast)
+#if __has_builtin(__builtin_bit_cast)
   return __builtin_bit_cast(To, from);
 #else
   To to;
   char *dst = reinterpret_cast<char *>(&to);
   const char *src = reinterpret_cast<const char *>(&from);
-#if LIBC_HAS_BUILTIN(__builtin_memcpy_inline)
+#if __has_builtin(__builtin_memcpy_inline)
   __builtin_memcpy_inline(dst, src, sizeof(To));
 #else
   for (unsigned i = 0; i < sizeof(To); ++i)
     dst[i] = src[i];
-#endif // LIBC_HAS_BUILTIN(__builtin_memcpy_inline)
+#endif // __has_builtin(__builtin_memcpy_inline)
   return to;
-#endif // LIBC_HAS_BUILTIN(__builtin_bit_cast)
+#endif // __has_builtin(__builtin_bit_cast)
 }
 
 template <typename T>
@@ -94,7 +93,7 @@ countr_zero(T value) {
   }
   return zero_bits;
 }
-#if LIBC_HAS_BUILTIN(__builtin_ctzs)
+#if __has_builtin(__builtin_ctzs)
 ADD_SPECIALIZATION(countr_zero, unsigned short, __builtin_ctzs)
 #endif
 ADD_SPECIALIZATION(countr_zero, unsigned int, __builtin_ctz)
@@ -124,7 +123,7 @@ countl_zero(T value) {
   }
   return zero_bits;
 }
-#if LIBC_HAS_BUILTIN(__builtin_clzs)
+#if __has_builtin(__builtin_clzs)
 ADD_SPECIALIZATION(countl_zero, unsigned short, __builtin_clzs)
 #endif
 ADD_SPECIALIZATION(countl_zero, unsigned int, __builtin_clz)

libc/src/__support/CPP/type_traits/add_pointer.h

@@ -10,7 +10,6 @@
 
 #include "src/__support/CPP/type_traits/remove_reference.h"
 #include "src/__support/CPP/type_traits/type_identity.h"
-#include "src/__support/macros/config.h"
 
 namespace LIBC_NAMESPACE::cpp {
 

libc/src/__support/CPP/type_traits/decay.h

@@ -9,7 +9,6 @@
 #define LLVM_LIBC_SRC___SUPPORT_CPP_TYPE_TRAITS_DECAY_H
 
 #include "src/__support/macros/attributes.h"
-#include "src/__support/macros/config.h"
 
 #include "src/__support/CPP/type_traits/add_pointer.h"
 #include "src/__support/CPP/type_traits/conditional.h"

libc/src/__support/CPP/type_traits/is_destructible.h

@@ -16,12 +16,11 @@
 #include "src/__support/CPP/type_traits/true_type.h"
 #include "src/__support/CPP/type_traits/type_identity.h"
 #include "src/__support/macros/attributes.h"
-#include "src/__support/macros/config.h"
 
 namespace LIBC_NAMESPACE::cpp {
 
 // is_destructible
-#if LIBC_HAS_BUILTIN(__is_destructible)
+#if __has_builtin(__is_destructible)
 template <typename T>
 struct is_destructible : bool_constant<__is_destructible(T)> {};
 #else

libc/src/__support/CPP/type_traits/is_function.h

@@ -12,12 +12,11 @@
 #include "src/__support/CPP/type_traits/is_const.h"
 #include "src/__support/CPP/type_traits/is_reference.h"
 #include "src/__support/macros/attributes.h"
-#include "src/__support/macros/config.h"
 
 namespace LIBC_NAMESPACE::cpp {
 
 // is_function
-#if LIBC_HAS_BUILTIN(__is_function)
+#if __has_builtin(__is_function)
 template <typename T>
 struct is_function : integral_constant<bool, __is_function(T)> {};
 #else

libc/src/__support/CPP/type_traits/is_lvalue_reference.h

@@ -12,12 +12,11 @@
 #include "src/__support/CPP/type_traits/false_type.h"
 #include "src/__support/CPP/type_traits/true_type.h"
 #include "src/__support/macros/attributes.h"
-#include "src/__support/macros/config.h"
 
 namespace LIBC_NAMESPACE::cpp {
 
 // is_lvalue_reference
-#if LIBC_HAS_BUILTIN(__is_lvalue_reference)
+#if __has_builtin(__is_lvalue_reference)
 template <typename T>
 struct is_lvalue_reference : bool_constant<__is_lvalue_reference(T)> {};
 #else

libc/src/__support/CPP/type_traits/is_reference.h

@@ -12,12 +12,11 @@
 #include "src/__support/CPP/type_traits/false_type.h"
 #include "src/__support/CPP/type_traits/true_type.h"
 #include "src/__support/macros/attributes.h"
-#include "src/__support/macros/config.h"
 
 namespace LIBC_NAMESPACE::cpp {
 
 // is_reference
-#if LIBC_HAS_BUILTIN(__is_reference)
+#if __has_builtin(__is_reference)
 template <typename T> struct is_reference : bool_constant<__is_reference(T)> {};
 #else
 template <typename T> struct is_reference : public false_type {};

libc/src/__support/CPP/type_traits/is_rvalue_reference.h

@@ -12,12 +12,11 @@
 #include "src/__support/CPP/type_traits/false_type.h"
 #include "src/__support/CPP/type_traits/true_type.h"
 #include "src/__support/macros/attributes.h"
-#include "src/__support/macros/config.h"
 
 namespace LIBC_NAMESPACE::cpp {
 
 // is_rvalue_reference
-#if LIBC_HAS_BUILTIN(__is_rvalue_reference)
+#if __has_builtin(__is_rvalue_reference)
 template <typename T>
 struct is_rvalue_reference : bool_constant<__is_rvalue_reference(T)> {};
 #else

libc/src/__support/CPP/type_traits/is_trivially_copyable.h

@@ -9,7 +9,6 @@
 #define LLVM_LIBC_SRC___SUPPORT_CPP_TYPE_TRAITS_IS_TRIVIALLY_COPYABLE_H
 
 #include "src/__support/CPP/type_traits/integral_constant.h"
-#include "src/__support/macros/config.h"
 
 namespace LIBC_NAMESPACE::cpp {
 

libc/src/__support/CPP/type_traits/is_trivially_destructible.h

@@ -11,12 +11,11 @@
 #include "src/__support/CPP/type_traits/bool_constant.h"
 #include "src/__support/CPP/type_traits/is_destructible.h"
 #include "src/__support/macros/attributes.h"
-#include "src/__support/macros/config.h"
 
 namespace LIBC_NAMESPACE::cpp {
 
 // is_trivially_destructible
-#if LIBC_HAS_BUILTIN(__is_trivially_destructible)
+#if __has_builtin(__is_trivially_destructible)
 template <typename T>
 struct is_trivially_destructible
     : public bool_constant<__is_trivially_destructible(T)> {};
@@ -25,7 +24,7 @@ template <typename T>
 struct is_trivially_destructible
     : public bool_constant<cpp::is_destructible_v<T> &&__has_trivial_destructor(
           T)> {};
-#endif // LIBC_HAS_BUILTIN(__is_trivially_destructible)
+#endif // __has_builtin(__is_trivially_destructible)
 template <typename T>
 LIBC_INLINE_VAR constexpr bool is_trivially_destructible_v =
     is_trivially_destructible<T>::value;

libc/src/__support/CPP/type_traits/remove_all_extents.h

@@ -9,14 +9,13 @@
 #define LLVM_LIBC_SRC___SUPPORT_CPP_TYPE_TRAITS_REMOVE_ALL_EXTENTS_H
 
 #include "src/__support/CPP/type_traits/type_identity.h"
-#include "src/__support/macros/config.h"
 
 #include <stddef.h> // size_t
 
 namespace LIBC_NAMESPACE::cpp {
 
 // remove_all_extents
-#if LIBC_HAS_BUILTIN(__remove_all_extents)
+#if __has_builtin(__remove_all_extents)
 template <typename T> using remove_all_extents_t = __remove_all_extents(T);
 template <typename T>
 struct remove_all_extents : cpp::type_identity<remove_all_extents_t<T>> {};

libc/src/__support/FPUtil/CMakeLists.txt

@@ -6,7 +6,6 @@ add_header_library(
     libc.include.fenv
     libc.include.math
     libc.src.__support.macros.attributes
-    libc.src.__support.macros.config
     libc.src.errno.errno
 )
 

libc/src/__support/FPUtil/FEnvImpl.h

@@ -11,7 +11,6 @@
 
 #include "include/llvm-libc-macros/math-macros.h"
 #include "src/__support/macros/attributes.h" // LIBC_INLINE
-#include "src/__support/macros/config.h"     // LIBC_HAS_BUILTIN
 #include "src/__support/macros/properties/architectures.h"
 #include "src/errno/libc_errno.h"
 #include <fenv.h>

libc/src/__support/FPUtil/gpu/FMA.h

@@ -10,12 +10,12 @@
 #define LLVM_LIBC_SRC___SUPPORT_FPUTIL_GPU_FMA_H
 
 #include "src/__support/CPP/type_traits.h"
-#include "src/__support/macros/config.h"
 
-// These intrinsics map to the FMA instrunctions in the target ISA for the GPU.
+// These intrinsics map to the FMA instructions in the target ISA for the GPU.
 // The default rounding mode generated from these will be to the nearest even.
-static_assert(LIBC_HAS_BUILTIN(__builtin_fma), "FMA builtins must be defined");
-static_assert(LIBC_HAS_BUILTIN(__builtin_fmaf), "FMA builtins must be defined");
+#if !__has_builtin(__builtin_fma) || !__has_builtin(__builtin_fmaf)
+#error "FMA builtins must be defined");
+#endif
 
 namespace LIBC_NAMESPACE {
 namespace fputil {

libc/src/__support/macros/config.h

@@ -13,24 +13,6 @@
 #ifndef LLVM_LIBC_SRC___SUPPORT_MACROS_CONFIG_H
 #define LLVM_LIBC_SRC___SUPPORT_MACROS_CONFIG_H
 
-// LIBC_HAS_BUILTIN()
-//
-// Checks whether the compiler supports a Clang Feature Checking Macro, and if
-// so, checks whether it supports the provided builtin function "x" where x
-// is one of the functions noted in
-// https://clang.llvm.org/docs/LanguageExtensions.html
-//
-// Note: Use this macro to avoid an extra level of #ifdef __has_builtin check.
-// http://releases.llvm.org/3.3/tools/clang/docs/LanguageExtensions.html
-
-// Compiler builtin-detection.
-// clang.llvm.org/docs/LanguageExtensions.html#has-builtin
-#ifdef __has_builtin
-#define LIBC_HAS_BUILTIN(x) __has_builtin(x)
-#else
-#define LIBC_HAS_BUILTIN(x) 0
-#endif
-
 // Compiler feature-detection.
 // clang.llvm.org/docs/LanguageExtensions.html#has-feature-and-has-extension
 #ifdef __has_feature