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Re: [RFC] fold Reorganization Plan
On Tue, 15 Feb 2005, Joe Buck wrote:
> The problem is that the user can independently set the IEEE rounding mode.
> This means that you can only fold floating point constants in cases where
> the generated result is exact; you cannot fold 1./3. for example.
You can fold 1./3. unless the user uses the FENV_ACCESS pragma to say you
can't in a particular region of the code. (Or -frounding-math while we
don't have FENV_ACCESS, although -frounding-math may not work fully either
as parts of the compiler may not be aware that the results of apparently
identical floating-point computations may depend on the rounding mode.)
Even with FENV_ACCESS, for C you still need to fold 1./3. in static
initializers (using the default rounding mode in that case).
--
Joseph S. Myers http://www.srcf.ucam.org/~jsm28/gcc/
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