[LLVMdev] ARM NEON VMUL.f32 issue

Renato Golin renato.golin at linaro.org
Tue Mar 19 11:17:06 PDT 2013


Hi folks,

I just "fixed" a bug on ARM LNT regarding lowering of a VMUL.f32 as NEON
and not VFP. The former is not IEEE 754 compliant, while the latter is, and
that was failing TSVC.

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?

The bugs in question...

Possible unsafe maths bug in NEON VMUL.f32
http://llvm.org/bugs/show_bug.cgi?id=15546

MultiSource/Benchmarks/TSVC/Reductions-flt tests beyond FLT_MIN
http://llvm.org/bugs/show_bug.cgi?id=15545

cheers,
--renato
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