[PATCH] D108925: [AMDGPU] enable scalar compare in truncate selection

[Stanislav Mekhanoshin via Phabricator via llvm-commits]

rampitec added inline comments.


================
Comment at: llvm/lib/Target/AMDGPU/SIInstructions.td:2112
+  (i1 (UniformUnaryFrag<trunc> i32:$a)),
+  (S_CMP_EQ_U32 (S_AND_B32 (i32 1), $a), (i32 1))
+>;
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rampitec wrote:
> alex-t wrote:
> > rampitec wrote:
> > > I think we can later fold it into
> > > ```
> > > s_bitcmp1_b32 $a, 0
> > > ```
> > For now, I would prefer to leave TODO here. Any objections?
> No objections, I also do not think we have to select it this way, but rather combine later.
What's interesting, S_AND_B32 will produce SCC = 1 on non-zero result just by itself! When you land it we may experiment with removing S_CMP from this pattern completely, although I am not sure how the rest of the BE prepared for the lack of compare and what would the pattern after propagating SCC from moveToVALU().


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  https://reviews.llvm.org/D108925/new/

https://reviews.llvm.org/D108925