------- Comment #15 from joseph at codesourcery dot com 2008-10-16 16:39 ------- Subject: Re: Optimization generates incorrect code with -frounding-math option (#pragma STDC FENV_ACCESS not implemented)
On Thu, 16 Oct 2008, vincent at vinc17 dot org wrote: > The compiler should generate correct code by default, and options like Sure, it generates correct code for the supported features, and <http://gcc.gnu.org/c99status.html>, which is linked from the manual, documents the state of support for the features: standard pragmas are documented as Missing and IEC 60559 support as Broken, with the explanation: * IEC 60559 is IEEE 754 floating point. This works if and only if the hardware is perfectly compliant, but GCC does not define __STDC_IEC_559__ or implement the associated standard pragmas; nor do some options such as -frounding-math to enable the pragmas globally work in all cases (for example, required exceptions may not be generated) and contracting expressions (e.g., using fused multiply-add) is not restricted to source-language expressions as required by C99. So you are using features documented not to be fully implemented and whether they will work is unpredictable. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34678
