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Re: [PATCH][4.3] Deprecate -ftrapv


On Feb 29, 2008, at 19:13, Richard Guenther wrote:
We wrap the libcalls inside libcall notes using REG_EQUAL notes
which indicate the libcalls compute non-trapping +-* (there's no
RTX code for the trappingness), so we combine and simplify the
operations making the libcall possibly dead and remove it again.

My patch from September (http://gcc.gnu.org/ml/gcc-patches/2007-09/ msg01351.html) should help with the libcall issue a bit, by making the trapping libcalls not be considered dead, even if optimizations make the results not get used. (Was I supposed to re-submit the patch in non-unidiff format? I've had a couple of machine die on me recently, I might have to reconstruct the source tree.) Of course, if the trapping math is optimized away before you get to emitting libcalls, that's a different bug.



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