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Fixes IBM XLC behavior with uint128 fallback #2985

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merged 3 commits into from
Jul 22, 2022
Merged

Fixes IBM XLC behavior with uint128 fallback #2985

merged 3 commits into from
Jul 22, 2022

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federico-busato
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IBM XLC compiler evaluates #if FMT_HAS_BUILTIN(__builtin_addcll) to true but __builtin_addcll is not supported and the compilation fails.

@vitaut
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vitaut commented Jul 16, 2022

Does it mean that __has_builtin is broken on IBM XLC? Please report to the compiler vendor.

As for the workaround, why make FMT_HAS_BUILTIN return false on this compiler if it doesn't work?

@federico-busato
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Does it mean that __has_builtin is broken on IBM XLC? Please report to the compiler vendor.

yes, I need further investigation to understand why __has_builtin does not work here. Just for completeness, I'm using xlc v16.1.1 compiler.

As for the workaround, why make FMT_HAS_BUILTIN return false on this compiler if it doesn't work?

FMT_HAS_BUILTIN(__builtin_addcll) return true and it enables the following line

__builtin_addcll(lo_, n, 0, &carry);

but __builtin_addcll is not supported by the compiler and this triggers the compile error.

please hold on. I would like to perform a couple of experiments to see if there are other solutions.

@federico-busato
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IBM xlc has two versions, the legacy one, and the clang-based. The problem occurs in the clang-based version. The reason is that FMT_HAS_BUILTIN(__builtin_addcll) is evaluated to true because actually clang supports it. However, the intrinsic function is not recognized/translated by the xlc backend. If needed, this is the message

fmt/include/fmt/format.h:397:11: error: 1540-2993 The builtin "__builtin_addcll" is not supported.
    lo_ = __builtin_addcll(lo_, n, 0, &carry);

vitaut
vitaut requested changes Jul 22, 2022
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@vitaut vitaut merged commit bc5c7c5 into fmtlib:master Jul 22, 2022
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vitaut commented Jul 22, 2022

Thanks!

mtremer referenced this pull request in ipfire/ipfire-2.x Nov 28, 2022
@pmu-ipf
fmt: Update to version 9.1.0
90d43e5 
- Update from version 9.0.0 to 9.1.0
- Update of rootfile
- Changelog
    9.1.0 - 2022-08-27
	* ``fmt::formatted_size`` now works at compile time
		  `#3026 <https://github.com/fmtlib/fmt/pull/3026>`_
			  For example (`godbolt <https://godbolt.org/z/1MW5rMdf8>`__):
			   .. code:: c++
			     #include <fmt/compile.h>
			     int main() {
			       using namespace fmt::literals;
			       constexpr size_t n = fmt::formatted_size("{}"_cf, 42);
			       fmt::print("{}\n", n); // prints 2
			     }
	* Fixed handling of invalid UTF-8
		  `#3038 <https://github.com/fmtlib/fmt/pull/3038>`_,
		  `#3044 <https://github.com/fmtlib/fmt/pull/3044>`_,
		  `#3056 <https://github.com/fmtlib/fmt/pull/3056>`_
	* Improved Unicode support in ``ostream`` overloads of ``print``
		  `#2994 <https://github.com/fmtlib/fmt/pull/2994>`_,
		  `#3001 <https://github.com/fmtlib/fmt/pull/3001>`_,
		  `#3025 <https://github.com/fmtlib/fmt/pull/3025>`_
	* Fixed handling of the sign specifier in localized formatting on systems with
	   32-bit ``wchar_t``
		  `#3041 <https://github.com/fmtlib/fmt/issues/3041>`_).
	* Added support for wide streams to ``fmt::streamed``
		  `#2994 <https://github.com/fmtlib/fmt/pull/2994>`_
	* Added the ``n`` specifier that disables the output of delimiters when
	   formatting ranges
		  `#2981 <https://github.com/fmtlib/fmt/pull/2981>`_,
		  `#2983 <https://github.com/fmtlib/fmt/pull/2983>`_
			  For example (`godbolt <https://godbolt.org/z/roKqGdj8c>`__):
			   .. code:: c++
			     #include <fmt/ranges.h>
			     #include <vector>
			     int main() {
			       auto v = std::vector{1, 2, 3};
			       fmt::print("{:n}\n", v); // prints 1, 2, 3
			     }
	* Worked around problematic ``std::string_view`` constructors introduced in C++23
		  `#3030 <https://github.com/fmtlib/fmt/issues/3030>`_,
		  `#3050 <https://github.com/fmtlib/fmt/issues/3050>`_
	* Improve handling (exclusion) of recursive ranges
		  `#2968 <https://github.com/fmtlib/fmt/issues/2968>`_,
		  `#2974 <https://github.com/fmtlib/fmt/pull/2974>`_
	* Improved error reporting in format string compilation
		  `#3055 <https://github.com/fmtlib/fmt/issues/3055>`_
	* Improved the implementation of
		  `Dragonbox <https://github.com/jk-jeon/dragonbox>`_, the algorithm used for
		   the default floating-point formatting
		  `#2984 <https://github.com/fmtlib/fmt/pull/2984>`_
	* Fixed issues with floating-point formatting on exotic platforms.
	* Improved the implementation of chrono formatting
		  `#3010 <https://github.com/fmtlib/fmt/pull/3010>`_
	* Improved documentation
		  `#2966 <https://github.com/fmtlib/fmt/pull/2966>`_,
		  `#3009 <https://github.com/fmtlib/fmt/pull/3009>`_,
		  `#3020 <https://github.com/fmtlib/fmt/issues/3020>`_,
		  `#3037 <https://github.com/fmtlib/fmt/pull/3037>`_
	* Improved build configuration
		  `#2991 <https://github.com/fmtlib/fmt/pull/2991>`_,
		  `#2995 <https://github.com/fmtlib/fmt/pull/2995>`_,
		  `#3004 <https://github.com/fmtlib/fmt/issues/3004>`_,
		  `#3007 <https://github.com/fmtlib/fmt/pull/3007>`_,
		  `#3040 <https://github.com/fmtlib/fmt/pull/3040>`_
	* Fixed various warnings and compilation issues
		  `#2969 <https://github.com/fmtlib/fmt/issues/2969>`_,
		  `#2971 <https://github.com/fmtlib/fmt/pull/2971>`_,
		  `#2975 <https://github.com/fmtlib/fmt/issues/2975>`_,
		  `#2982 <https://github.com/fmtlib/fmt/pull/2982>`_,
		  `#2985 <https://github.com/fmtlib/fmt/pull/2985>`_,
		  `#2988 <https://github.com/fmtlib/fmt/issues/2988>`_,
		  `#3000 <https://github.com/fmtlib/fmt/issues/3000>`_,
		  `#3006 <https://github.com/fmtlib/fmt/issues/3006>`_,
		  `#3014 <https://github.com/fmtlib/fmt/issues/3014>`_,
		  `#3015 <https://github.com/fmtlib/fmt/issues/3015>`_,
		  `#3021 <https://github.com/fmtlib/fmt/pull/3021>`_,
		  `#3023 <https://github.com/fmtlib/fmt/issues/3023>`_,
		  `#3024 <https://github.com/fmtlib/fmt/pull/3024>`_,
		  `#3029 <https://github.com/fmtlib/fmt/pull/3029>`_,
		  `#3043 <https://github.com/fmtlib/fmt/pull/3043>`_,
		  `#3052 <https://github.com/fmtlib/fmt/issues/3052>`_,
		  `#3053 <https://github.com/fmtlib/fmt/pull/3053>`_,
		  `#3054 <https://github.com/fmtlib/fmt/pull/3054>`_

Signed-off-by: Adolf Belka <[email protected]>
Reviewed-by: Michael Tremer <[email protected]>
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@vitaut vitaut vitaut approved these changes

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@federico-busato @vitaut @fbusato