[LLVMdev] ARM NEON VMUL.f32 issue

David Tweed David.Tweed at arm.com
Wed Mar 20 02:58:25 PDT 2013


Hi,

| The question is:
| * is this a problem with the test, that shouldn't be expecting values below FLT_MIN, or
| * is it a bug in the lowering, that should only be lowering to NEON's VMUL when unsafe-math is on, or
| * neither, and people should disable that when they want correctness?

Note that if you go for the second option, IMO unsafe-math is _far_ too "aggressive" an option to control this whether multiplies should be allowed produce denormals. I can imagine plenty of cases where I wouldn't care about denormals, but wouldn't want some of the other fast-math semantics applied. Does llvm/clang have any option like strict-iee754 that users can toggle to control things like this?

Cheers,
Dave

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