[PATCH] D63216: [AMDGPU] ImmArg and SourceOfDivergence for permlane/dpp

[Stanislav Mekhanoshin via Phabricator via llvm-commits]

rampitec added inline comments.


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Comment at: lib/Target/AMDGPU/AMDGPUSearchableTables.td:102-104
+def : SourceOfDivergence<int_amdgcn_mov_dpp>;
+def : SourceOfDivergence<int_amdgcn_mov_dpp8>;
+def : SourceOfDivergence<int_amdgcn_update_dpp>;
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arsenm wrote:
> I'm not 100% sure on DPP. If it's called with uniform arguments, even though you read from another lane, every lane should read the same value? Is this not the case with some of the source types?
I think it is divergent even if all arguments are uniform. Another lane may have been updated when exec mask was different. Our DA considers values uniform only across active lanes. I.e. if you have and if..then a value inside a block will deem uniform even if it may be different in the else block.


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https://reviews.llvm.org/D63216