This is a feature request. It stems from a discussion on gcc-help ("RE: Internal representation of double variables - 3.4.6 vs 4.1.0").
There is no general, high-level option to enforce any particular arithmetic model. Thus running floating point code on different CPUs may give different results. While this is a normal feature of floating point arithmetic, there are well-defined models (such as the IEEE models) that allow for consistent results without the influence of idiosyncrasies such as the x86 80 bit registers. Currently, options that give more consistent behaviour are architecture specific (such as -mfpmath=sse). A top-level option to turn on these options without having to dig into architecture-specific details would be an excellent addition. Having an option to switch off a set of optimisations that impact on the floating point precision would also be a wonderful thing. In other words, I'm after an analogue of ifort's -mp/-fltconsistency/-mieee-fp. -- Summary: Consistent floating point arithmetic model option Product: gcc Version: unknown Status: UNCONFIRMED Severity: enhancement Priority: P3 Component: fortran AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: terry at chem dot gu dot se http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31114