[PATCH] D24070: Setting fp trapping mode and denormal type

Sjoerd Meijer via llvm-commits llvm-commits at lists.llvm.org
Fri Sep 2 13:21:06 PDT 2016

SjoerdMeijer added inline comments.

Comment at: llvm/trunk/include/llvm/CodeGen/CommandFlags.h:158-159
@@ +157,4 @@
+          cl::desc("Select which denormal numbers the code is permitted to require"),
arsenm wrote:
> SjoerdMeijer wrote:
> > arsenm wrote:
> > > Should this be per-FP type? We currently use a subtarget feature for this but need to split between f16/f32/f64
> > I now see how you are using it. We adopted the same approach as some other fp options (no NaNs, no infs, etc), which are also not per FP type. So to be honest, I don't know if they should. 
> The other options are quite different from this. They are optimization hints that aren't required for correctness (and also are deprecated in favor of the per-instruction flags). The global denormal handling mode is different and required
One approach to implement setting denormals per-FP type could be to consider this as the "global flag" that sets all these per-type flags. Then any combination can be made by using the global flag that sets all, or omit it and specify one or more of the per-type flags.



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