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[Bug math/21684] tgmath.h handling of complex integers


https://sourceware.org/bugzilla/show_bug.cgi?id=21684

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commit d9bef9c0a41bc3ca4036542cbf2a7d2d0cf60237
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Tue Aug 22 17:55:42 2017 +0000

    Fix tgmath.h handling of complex integers (bug 21684).

    The tgmath.h macros return a real type not a complex type when an
    argument is of complex integer type (a GNU extension) and there are no
    arguments of complex floating type.  It seems clear that just as real
    integers are mapped to double for tgmath.h, so complex integers should
    be mapped to _Complex double.

    This patch implements such a mapping.  The main complication in fixing
    this bug is that the tgmath.h macros expand their arguments a large
    number of times, resulting in exponential blowup of the size of the
    expansion when calls to tgmath.h macros are used in the arguments of
    such macros; it would be unfortunate for fixing a bug with a fairly
    obscure extension to make the macros expand their arguments even more
    times.  Thus, this patch optimizes the definitions of the relevant
    macros.  __tgmath_real_type previously expanded its argument 7 times
    and now expands it 3 times.  __tgmath_complex_type, used in place of
    __tgmath_real_type only for functions that might return either real or
    complex types, not for complex functions that always return real types
    or always return complex types, expands its argument 5 times.  So the
    sizes of the macro expansions from nested macro calls are
    correspondingly reduced (remembering that each tgmath.h macro expands
    __tgmath_real_type, or sometimes now __tgmath_complex_type, several
    times).

    Sometimes the real return type resulted from calling a complex
    function and converting the result to a real type; sometimes it
    resulted from calling a real function, because the logic for
    determining whether arguments were real or complex, based on sizeof,
    was confused by integer promotions applying to e.g. short int but not
    _Complex short int.  The relevant tests are converted to use a new
    macro __expr_is_real, which, by calling __builtin_classify_type rather
    than comparing the results of two calls to sizeof, also reduces the
    number of times macros expand their arguments.

    Although there are reductions in the number of times macros expand
    their arguments, I do not consider this to fix bug 21660, since a
    proper fix means each macro expanding its arguments only once (via
    using new compiler features designed for that purpose).

    Tested for x86_64.

        [BZ #21684]
        * math/tgmath.h (__floating_type): Simplify definitions.
        (__real_integer_type): New macro.
        (__complex_integer_type): Likewise.
        (__expr_is_real): Likewise.
        (__tgmath_real_type_sub): Update comment to describe handling of
        complex types.
        (__tgmath_complex_type_sub): New macro.
        (__tgmath_complex_type): Likewise.
        [__HAVE_FLOAT128 && __GLIBC_USE (IEC_60559_TYPES_EXT)]
        (__TGMATH_CF128): Use __expr_is_real.
        (__TGMATH_UNARY_REAL_IMAG): Use __tgmath_complex_type and
        __expr_is_real.
        (__TGMATH_BINARY_REAL_IMAG): Likewise.
        (__TGMATH_UNARY_REAL_IMAG_RET_REAL): Use __expr_is_real.
        * math/gen-tgmath-tests.py (Type.create_type): Create complex
        integer types.

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog                |   20 +++++++
 math/gen-tgmath-tests.py |    4 +-
 math/tgmath.h            |  135 ++++++++++++++++++++++++++++++----------------
 3 files changed, 110 insertions(+), 49 deletions(-)

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