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added additional macro FASTFLOAT_ONLY_ROUNDS_TO_NEAREST_SUPPORTED for performance improve.

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IRainman 2025-04-30 00:56:02 +03:00
parent 17ffdffdd9
commit c99930b2a0
1 changed files with 6 additions and 0 deletions
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6
include/fast_float/parse_number.h
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@ -75,6 +75,7 @@ from_chars_result_t<UC>
} }
#endif #endif
#ifndef FASTFLOAT_ONLY_ROUNDS_TO_NEAREST_SUPPORTED
/** /**
* Returns true if the floating-pointing rounding mode is to 'nearest'. * Returns true if the floating-pointing rounding mode is to 'nearest'.
* It is the default on most system. This function is meant to be inexpensive. * It is the default on most system. This function is meant to be inexpensive.
@ -139,6 +140,7 @@ fastfloat_really_inline bool rounds_to_nearest() noexcept {
#pragma GCC diagnostic pop #pragma GCC diagnostic pop
#endif #endif
} }
#endif
} // namespace detail } // namespace detail
@ -226,7 +228,9 @@ from_chars_advanced(parsed_number_string_t<UC> const &pns, T &value) noexcept {
// We could check it first (before the previous branch), but // We could check it first (before the previous branch), but
// there might be performance advantages at having the check // there might be performance advantages at having the check
// be last. // be last.
#ifndef FASTFLOAT_ONLY_ROUNDS_TO_NEAREST_SUPPORTED
if (!cpp20_and_in_constexpr() && detail::rounds_to_nearest()) { if (!cpp20_and_in_constexpr() && detail::rounds_to_nearest()) {
#endif
// We have that fegetround() == FE_TONEAREST. // We have that fegetround() == FE_TONEAREST.
// Next is Clinger's fast path. // Next is Clinger's fast path.
if (pns.mantissa <= binary_format<T>::max_mantissa_fast_path()) { if (pns.mantissa <= binary_format<T>::max_mantissa_fast_path()) {
@ -243,6 +247,7 @@ from_chars_advanced(parsed_number_string_t<UC> const &pns, T &value) noexcept {
#endif #endif
return answer; return answer;
} }
#ifndef FASTFLOAT_ONLY_ROUNDS_TO_NEAREST_SUPPORTED
} else { } else {
// We do not have that fegetround() == FE_TONEAREST. // We do not have that fegetround() == FE_TONEAREST.
// Next is a modified Clinger's fast path, inspired by Jakub Jelínek's // Next is a modified Clinger's fast path, inspired by Jakub Jelínek's
@ -271,6 +276,7 @@ from_chars_advanced(parsed_number_string_t<UC> const &pns, T &value) noexcept {
return answer; return answer;
} }
} }
#endif
} }
adjusted_mantissa am = adjusted_mantissa am =
compute_float<binary_format<T>>(pns.exponent, pns.mantissa); compute_float<binary_format<T>>(pns.exponent, pns.mantissa);