search for: fcomi

Hello there, I recently started working on the LLVM backend for a target that doesn't support x87 instructions. Currently, I am in the process of completely disabling some x87 instructions such as fcomi, fcompi,... for a specific sub-target. I also do not have SSE enabled for my sub-target, and llvm resorts to fcomi* instructions for FP compare instructions. Is there a way to bypass the automatic optimization that generates the x87 instructions when SSE is disabled, and completely eliminate the c...

...sure if I understand your question correctly: Do you need to generate code that contains no x87 floating-point instructions altogether, but uses calls into a soft-float library instead? That behaviour can be enabled using the "-soft-float" flag, as far as I know. Or is it only about the fcomi* instructions, which are not supported by pre-Pentium Pro chips? Then I have good news: I have been working on getting this bug [1] fixed, and I'm planning to submit a patch within the next few days (hopefully in time for the 3.1 release). Best regards, Christoph [1] http://llvm.org/bugs/show...

...> > This bit also exposes a lot of flexibility and control to the front- end. In > particular, gcc supports the -fhonor-snans flag, which would enable the trap > bit on (basically) all floating point operations. The presense of this flag > would trigger generation of the fcomi instruction instead of fucomi (on X86) > for example, and would inhibit optimizations that would break the semantics of > the program. There is no -fhonor-snans; I guess you mean -fsignaling-nans here. And -fsignaling-nans doesn't mean use fcomi instead of fucomi; the -ffinite-mat...