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author | Joseph Myers <joseph@codesourcery.com> | 2023-01-06 19:33:29 +0000 |
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committer | Joseph Myers <joseph@codesourcery.com> | 2023-01-06 19:33:29 +0000 |
commit | 8a78f833d670f86302f2d0c32eb1e4357d9166ff (patch) | |
tree | 29244a0fd632b5b77d6847ac40dd92d6197d9953 /soft-fp/quad.h | |
parent | 35141f304e319109c322f797ae71c0b9420ccb05 (diff) | |
download | glibc-8a78f833d670f86302f2d0c32eb1e4357d9166ff.tar.gz glibc-8a78f833d670f86302f2d0c32eb1e4357d9166ff.tar.xz glibc-8a78f833d670f86302f2d0c32eb1e4357d9166ff.zip |
C2x semantics for <tgmath.h>
<tgmath.h> implements semantics for integer generic arguments that handle cases involving _FloatN / _FloatNx types as specified in TS 18661-3 plus some defect fixes. C2x has further changes to the semantics for <tgmath.h> macros with such types, which should also be considered defect fixes (although handled through the integration of TS 18661-3 in C2x rather than through an issue tracking process). Specifically, the rules were changed because of problems raised with using the macros with the evaluation format types such as float_t and _Float32_t: the older version of the rules didn't allow passing _FloatN / _FloatNx types to the narrowing macros returning float or double, or passing float / double / long double to the narrowing macros returning _FloatN / _FloatNx, which was a problem with the evaluation format types which could be either kind of type depending on the value of FLT_EVAL_METHOD. Thus the new rules allow cases of mixing types which were not allowed before, and, as part of the changes, the handling of integer arguments was also changed: if there is any _FloatNx generic argument, integer generic arguments are treated as _Float32x (not double), while the rule about treating integer arguments to narrowing macros returning _FloatN or _FloatNx as _Float64 not double was removed (no longer needed now double is a valid argument to such macros). I've implemented the changes in GCC's __builtin_tgmath, which thus requires updates to glibc's test expectations so that the tests continue to build with GCC 13 (the test is also updated to test the argument types that weren't allowed before but are now valid under C2x rules). Given those test changes, it's then also necessary to fix the implementations in <tgmath.h> to have appropriate semantics with older GCC so that the tests pass with GCC versions before GCC 13 as well. For some cases (non-narrowing macros with two or three generic arguments; narrowing macros returning _Float32x), the older version of __builtin_tgmath doesn't correspond sufficiently well to C2x semantics, so in those cases <tgmath.h> is adjusted to use the older macro implementation instead of __builtin_tgmath. The older macro implementation is itself adjusted to give the desired semantics, with GCC 7 and later. (It's not possible to get the right semantics in all cases for the narrowing macros with GCC 6 and before when the _FloatN / _FloatNx names are typedefs rather than distinct types.) Tested as follows: with the full glibc testsuite for x86_64, GCC 6, 7, 11, 13; with execution of the math/tests for aarch64, arm, powerpc and powerpc64le, GCC 6, 7, 12 and 13 (powerpc64le only with GCC 12 and 13); with build-many-glibcs.py with GCC 6, 7, 12 and 13.
Diffstat (limited to 'soft-fp/quad.h')
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