[PATCH] D70181: [MVE] [ARM] Select VQABS

[Sjoerd Meijer via Phabricator via llvm-commits]

SjoerdMeijer added inline comments.


================
Comment at: llvm/lib/Target/ARM/ARMInstrMVE.td:1955
 
+let Predicates = [HasMVEInt] in {
+  def : Pat<(v16i8 (vselect
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simon_tatham wrote:
> SjoerdMeijer wrote:
> > Should this be `HasMVEFloat`?
> No – VQABS is an integer instruction. The point is that it takes the absolute value of a signed integer, and gives you back something that fits in the same signed integer type, which means it has to map the largest negative value (say -128) to //one less// than its true absolute value (e.g. +127) or else it still ends up negative.
Ah yes, but think I got confused by the 

   ExecuteFPCheck();

in the pseudo-code of the instruction. And not that it really matters, but I guess that means the test just needs `-mattr=+mve` instead of  `-mattr=+mve.fp` 




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  https://reviews.llvm.org/D70181/new/

https://reviews.llvm.org/D70181