On Tue, 6 Feb 2018, Vincent Lefevre wrote: > The issues were also present on 64-bit platforms and were due to > a bug in mpfr_div_ui, which has always been present, since 1999. > With MPFR 4.0.0, they are also visible with mpfr_div just because > mpfr_div now uses mpfr_div_ui in some simple cases. I don't think > that GCC could be affected because AFAIK, a failure can only occur > when the input and output precisions are different, or is this > possible with GCC?
GCC doesn't use mpfr_div at all; it uses MPFR to fold calls to a range of libm functions with constant arguments (input and output precisions should always be the same, since GCC doesn't yet support built-in functions for the TS 18661-1 narrowing functions such as fsqrtl), and for correctly rounding conversions of decimal strings to binary floating point. The + - * / operations are handled directly in real.c without use of MPFR. Of course MPFR functions called might use mpfr_div indirectly. -- Joseph S. Myers jos...@codesourcery.com
