~vcs-imports-ii/mpfr/trunk

Viewing changes to src/mpfr-impl.h

[src/mpfr-impl.h] Updated UBF comment about aliasing rules.

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(see changeset r13820 in the ubf2 branch). So, for the time being,

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as long as the code does not break, do not change anything.

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Note: The condition "use mpfr_ptr to access the usual mpfr_t members and

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mpfr_ubf_ptr to access the additional member _mpfr_zexp" may be ignored

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if the union type is visible within the function (see ISO C99 6.5.2.3#5

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and 6.5.2.3#8 for the example, this implementation being very similar to

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the valid fragment of this example), which must be the case as the union

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is declared globally. However, this seems to be buggy in GCC:

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=14319

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65892

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Alternatively, GCC's may_alias attribute could conditionally be used

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on the __mpfr_ubf_struct and __mpfr_struct types (though it would be

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much stronger than needed since only these two types may alias each