Revert "WIP: preserve original implementation in case when libm can't provide cexp functions"

This reverts commit bda7bce.

Author: nurmukhametov

libcxx/CMakeLists.txt

@@ -749,7 +749,6 @@ config_define(${LIBCXX_ENABLE_UNICODE} _LIBCPP_HAS_UNICODE)
 config_define(${LIBCXX_ENABLE_WIDE_CHARACTERS} _LIBCPP_HAS_WIDE_CHARACTERS)
 config_define(${LIBCXX_ENABLE_TIME_ZONE_DATABASE} _LIBCPP_HAS_TIME_ZONE_DATABASE)
 config_define(${LIBCXX_ENABLE_VENDOR_AVAILABILITY_ANNOTATIONS} _LIBCPP_HAS_VENDOR_AVAILABILITY_ANNOTATIONS)
-config_define_if(C_SUPPORTS_C99_COMPLEX _LIBCPP_HAS_C99_COMPLEX)
 
 # TODO: Remove in LLVM 21. We're leaving an error to make this fail explicitly.
 if (LIBCXX_ENABLE_ASSERTIONS)

libcxx/cmake/config-ix.cmake

@@ -103,31 +103,6 @@ endif()
 
 check_symbol_exists(__PICOLIBC__ "string.h" PICOLIBC)
 
-# Check for the existence of <complex.h> complex math functions.
-# This is necessary even though libcxx uses the builtin versions
-# of these functions, because if the builtin cannot be used, a reference
-# to the library function is emitted. Using compiler builtins for these
-# functions requires corresponding C99 library functions to be present.
-
-cmake_push_check_state()
-list(APPEND CMAKE_REQUIRED_LIBRARIES m)
-check_c_source_compiles("
-#include <complex.h>
-typedef __complex__ float float_type;
-typedef __complex__ double double_type;
-typedef __complex__ long double ld_type;
-volatile float_type tmpf;
-volatile double_type tmpd;
-volatile ld_type tmpld;
-int main(void) {
-  tmpf = cexpf(tmpf);
-  tmpd = cexp(tmpd);
-  tmpld = cexpl(tmpld);
-  return 0;
-}
-" C_SUPPORTS_C99_COMPLEX)
-cmake_pop_check_state()
-
 # Check libraries
 if(WIN32 AND NOT MINGW)
   # TODO(compnerd) do we want to support an emulation layer that allows for the

libcxx/include/__config_site.in

@@ -32,7 +32,6 @@
 #cmakedefine01 _LIBCPP_HAS_WIDE_CHARACTERS
 #cmakedefine01 _LIBCPP_HAS_TIME_ZONE_DATABASE
 #cmakedefine01 _LIBCPP_INSTRUMENTED_WITH_ASAN
-#cmakedefine01 _LIBCPP_HAS_C99_COMPLEX
 
 // PSTL backends
 #cmakedefine _LIBCPP_PSTL_BACKEND_SERIAL

libcxx/include/complex

@@ -1074,7 +1074,6 @@ _LIBCPP_HIDE_FROM_ABI complex<_Tp> sqrt(const complex<_Tp>& __x) {
 
 // exp
 
-#  if _LIBCPP_HAS_C99_COMPLEX
 _LIBCPP_HIDE_FROM_ABI inline _Complex float __cexp(_Complex float __v) { return __builtin_cexpf(__v); }
 _LIBCPP_HIDE_FROM_ABI inline _Complex double __cexp(_Complex double __v) { return __builtin_cexp(__v); }
 _LIBCPP_HIDE_FROM_ABI inline _Complex long double __cexp(_Complex long double __v) { return __builtin_cexpl(__v); }
@@ -1083,31 +1082,6 @@ template <class _Tp>
 _LIBCPP_HIDE_FROM_ABI complex<_Tp> exp(const complex<_Tp>& __x) {
   return complex<_Tp>(__from_builtin_tag(), std::__cexp(__x.__builtin()));
 }
-#  else
-template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI complex<_Tp> exp(const complex<_Tp>& __x) {
-  _Tp __i = __x.imag();
-  if (__i == 0) {
-    return complex<_Tp>(std::exp(__x.real()), std::copysign(_Tp(0), __x.imag()));
-  }
-  if (std::isinf(__x.real())) {
-    if (__x.real() < _Tp(0)) {
-      if (!std::isfinite(__i))
-        __i = _Tp(1);
-    } else if (__i == 0 || !std::isfinite(__i)) {
-      if (std::isinf(__i))
-        __i = _Tp(NAN);
-      return complex<_Tp>(__x.real(), __i);
-    }
-  }
-  _Tp __e = std::exp(__x.real());
-  if (std::isinf(__e)) {
-    _Tp __e2 = std::exp(__x.real() * _Tp(0.5));
-    return complex<_Tp>(__e2 * std::cos(__i) * __e2, __e2 * std::sin(__i) * __e2);
-  }
-  return complex<_Tp>(__e * std::cos(__i), __e * std::sin(__i));
-}
-#  endif
 
 // pow