Tested powerpc64le-linux, pushed to trunk.
We can use the new from_chars implementation when long double and double
have the same representation.
libstdc++-v3/ChangeLog:
* src/c++17/floating_from_chars.cc (USE_STRTOD_FOR_FROM_CHARS):
Define macro for case where std::from_chars is implemented in
terms of strtod, strtof or strtold.
(buffer_resource, valid_fmt, find_end_of_float, pattern)
(from_chars_impl, make_result, reserve_string): Do not define
unless USE_STRTOD_FOR_FROM_CHARS is defined.
(from_chars): Define when at least one of USE_LIB_FAST_FLOAT and
USE_STRTOD_FOR_FROM_CHARS is defined, instead of
_GLIBCXX_HAVE_USELOCALE. Use fast_float for long double when it
is binary64.
---
libstdc++-v3/src/c++17/floating_from_chars.cc | 38 ++++++++++++++++---
1 file changed, 32 insertions(+), 6 deletions(-)
diff --git a/libstdc++-v3/src/c++17/floating_from_chars.cc
b/libstdc++-v3/src/c++17/floating_from_chars.cc
index 3158a3a96d3..ba1345db3f2 100644
--- a/libstdc++-v3/src/c++17/floating_from_chars.cc
+++ b/libstdc++-v3/src/c++17/floating_from_chars.cc
@@ -46,6 +46,13 @@
# include <xlocale.h>
#endif
+#if _GLIBCXX_HAVE_USELOCALE
+// FIXME: This should be reimplemented so it doesn't use strtod and newlocale.
+// That will avoid the need for any memory allocation, meaning that the
+// non-conforming errc::not_enough_memory result cannot happen.
+# define USE_STRTOD_FOR_FROM_CHARS 1
+#endif
+
#ifdef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT
#ifndef __LONG_DOUBLE_IBM128__
#error "floating_from_chars.cc must be compiled with -mabi=ibmlongdouble"
@@ -56,6 +63,9 @@ extern "C" __ieee128 __strtoieee128(const char*, char**);
#if _GLIBCXX_FLOAT_IS_IEEE_BINARY32 && _GLIBCXX_DOUBLE_IS_IEEE_BINARY64
# define USE_LIB_FAST_FLOAT 1
+# if __LDBL_MANT_DIG__ == __DBL_MANT_DIG__
+# undef USE_STRTOD_FOR_FROM_CHARS
+# endif
#endif
#if USE_LIB_FAST_FLOAT
@@ -66,13 +76,13 @@ namespace
} // anon namespace
#endif
-#if _GLIBCXX_HAVE_USELOCALE
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
namespace
{
+#if USE_STRTOD_FOR_FROM_CHARS
// A memory resource with a static buffer that can be used for small
// allocations. At most one allocation using the freestore can be done
// if the static buffer is insufficient. The callers below only require
@@ -409,6 +419,7 @@ namespace
return true;
}
#endif
+#endif // USE_STRTOD_FOR_FROM_CHARS
#if _GLIBCXX_FLOAT_IS_IEEE_BINARY32 && _GLIBCXX_DOUBLE_IS_IEEE_BINARY64
// If the given ASCII character represents a hexit, return that hexit.
@@ -771,13 +782,11 @@ namespace
return {first, errc{}};
}
-#endif
+#endif // _GLIBCXX_FLOAT_IS_IEEE_BINARY32 && _GLIBCXX_DOUBLE_IS_IEEE_BINARY64
} // namespace
-// FIXME: This should be reimplemented so it doesn't use strtod and newlocale.
-// That will avoid the need for any memory allocation, meaning that the
-// non-conforming errc::not_enough_memory result cannot happen.
+#if USE_LIB_FAST_FLOAT || USE_STRTOD_FOR_FROM_CHARS
from_chars_result
from_chars(const char* first, const char* last, float& value,
@@ -855,6 +864,21 @@ from_chars_result
from_chars(const char* first, const char* last, long double& value,
chars_format fmt) noexcept
{
+#if _GLIBCXX_FLOAT_IS_IEEE_BINARY32 && _GLIBCXX_DOUBLE_IS_IEEE_BINARY64 \
+ && ! USE_STRTOD_FOR_FROM_CHARS
+ double dbl_value;
+ from_chars_result result;
+ if (fmt == chars_format::hex)
+ result = __floating_from_chars_hex(first, last, dbl_value);
+ else
+ {
+ static_assert(USE_LIB_FAST_FLOAT);
+ result = fast_float::from_chars(first, last, dbl_value, fmt);
+ }
+ if (result.ec == errc{})
+ value = dbl_value;
+ return result;
+#else
errc ec = errc::invalid_argument;
#if _GLIBCXX_USE_CXX11_ABI
buffer_resource mr;
@@ -875,6 +899,7 @@ from_chars(const char* first, const char* last, long
double& value,
fmt = chars_format{};
}
return make_result(first, len, fmt, ec);
+#endif
}
#ifdef _GLIBCXX_LONG_DOUBLE_COMPAT
@@ -909,6 +934,7 @@ from_chars(const char* first, const char* last, __ieee128&
value,
}
#endif
+#endif // USE_LIB_FAST_FLOAT || USE_STRTOD_FOR_FROM_CHARS
+
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
-#endif // _GLIBCXX_HAVE_USELOCALE
--
2.31.1
