Patch RFA: Let languages control -ffast-math
Joseph S. Myers
joseph@codesourcery.com
Sun Feb 6 19:03:00 GMT 2011
On Sat, 5 Feb 2011, Ian Lance Taylor wrote:
> This patch adds a new language hook apply_combined_option which lets the
> frontend control whether a meta-option like -ffast-math should affect
> another more specific option. This is a general mechanism and is named
> accordingly, but in fact at present it seems only appropriate for
> -ffast-math and -funsafe-math-optimizations, so I would be willing to
> give it a more specific name if that seems appropriate.
opts.c is not meant to use langhooks; I moved anything that would be
problematic to share with the driver into opts-global.c so that opts.c can
in future be shared with the driver. So it would be better in that
regard, though less general, for the init_options langhook to set
something in the gcc_options struct indicating that a particular option
should not be controlled by -ffast-math.
(Various targets have linker specs
%{ffast-math|funsafe-math-optimizations:crtfastmath.o%s} and it would be
good if in future they could be based on logical state of
flag_unsafe_math_optimizations in the driver, so knowing these
implications in the driver is potentially useful. But certainly such
driver processing can only operate with language-independent defaults
since it may be linking a multi-language program.)
--
Joseph S. Myers
joseph@codesourcery.com
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