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libstdc++: Fix std::to_chars for IEEE128 long double 

The preprocessor check for _GLIBCXX_USE_FLOAT128 is the wrong condition,
because when the compiler is built with --with-long-double-format=ieee
configure determines that __float128 is the same as long double, and so
should not be used. But we do want the std::to_chars overloads for
__float128 in that case, because the floating_to_chars.cc file is built
with -mabi=ibmlongdouble and so the __float128 overloads are actually
the 'long double' ones for -mabi=ieeelongdouble code.

This fixes missing definitions of the __float128 overloads of
std::to_chars for --with-long-double-format=ieee builds. Without this,
there are symbols present in the --with-long-double-abi=ibm build which
are missing from the --with-long-double-abi=ieee build.

libstdc++-v3/ChangeLog:

	* src/c++17/floating_to_chars.cc (FLOAT128_TO_CHARS): Depend on
	LONG_DOUBLE_ALT128_COMPAT instead of USE_FLOAT128.
This commit is contained in:
Jonathan Wakely 2022-02-10 14:06:27 +00:00
parent f320197c8b
commit 8134156502
1 changed files with 2 additions and 6 deletions
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8
libstdc++-v3/src/c++17/floating_to_chars.cc
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@ -76,16 +76,12 @@ extern "C" int __sprintfieee128(char*, const char*, ...);
# define LONG_DOUBLE_KIND LDK_UNSUPPORTED
#endif
#if defined _GLIBCXX_USE_FLOAT128 && __FLT128_MANT_DIG__ == 113
// For now we only support __float128 when it's the powerpc64 __ieee128 type.
#if defined _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT && __FLT128_MANT_DIG__ == 113
// Define overloads of std::to_chars for __float128.
# define FLOAT128_TO_CHARS 1
#endif
// For now we only support __float128 when it's the powerpc64 __ieee128 type.
#ifndef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT
# undef FLOAT128_TO_CHARS
#endif
#ifdef FLOAT128_TO_CHARS
using F128_type = __float128;
#else