[PATCH] D67517: Create UsersManual section entitled 'Controlling Floating Point Behavior'

Fri Sep 13 14:11:40 PDT 2019

rjmccall added inline comments.

================
Comment at: clang/docs/UsersManual.rst:1213
+
+.. option:: -f[no-]honor-nans
+
----------------
andrew.w.kaylor wrote:
> rjmccall wrote:
> > cameron.mcinally wrote:
> > > mibintc wrote:
> > > > Both honor-nans and honor-infinities appear to have no effect at the moment, previously they were mapped to -menable-no-infs -menable-no-nans
> > > I believe others have the same problem too. All probably need to be reassessed. E.g. I think -f[no-]trapping-math isn't hooked up to anything in LLVM.
> > > 
> > > This may also get confusing when the -fp-model=/etc options are added, since they really do the same thing in different ways.
> > > 
> > > Is there a plan in place for how to handle this? Will the GCC options alias the Clang options?
> > If we accept these options, we should document them, even if just to say that they currently have no effect.  But I suspect that what this means is that they have no effect *separately* and we currently only enable NaN/Inf-unsafe optimizations given a more aggressive option like fast-math.
> We have a fast-math flag for this (ninf and nnan). The front end should be connecting these options to those flags.
Okay.  Let's keep this patch about documentation, and if we find semantic problems, we can address those in follow-ups.  So if these currently do nothing, we should document them that way.

Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D67517/new/

https://reviews.llvm.org/D67517