[PATCH] D34844: [AMDGPU] Always use rcp + mul with fast math

[Stanislav Mekhanoshin via Phabricator via llvm-commits]

rampitec added inline comments.


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Comment at: lib/Target/AMDGPU/SIISelLowering.cpp:3780
     SDNodeFlags NewFlags;
     NewFlags.setUnsafeAlgebra(true);
     SDValue Recip = DAG.getNode(AMDGPUISD::RCP, SL, VT, RHS);
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rampitec wrote:
> rampitec wrote:
> > arsenm wrote:
> > > This is a possible source of errors now that less-strict flags can now trigger this
> > That is the intent to trigger this. That is how HSAIL compiler works and we had no complaints so far. Anyway, I am running confirmance now.
> > 
> > A philosophical question though what shall preval, unsafe fp or denorm support. Once again, HSAIL favors relaxation, so I did the same.
> > 
> > In fact this implementation is stricter than one we have in HSAIL. We were applying options to library as well, while here it is only applied to user code.
> Actually fp denorms are not supported with 2.5 ulp fdiv even now, so there is no change in this respect.
JFYI. OCL conformance passed.


https://reviews.llvm.org/D34844