[PATCH] D35267: Pass Divergence Analysis data to selection DAG to drive divergence dependent instruction selection

Alexander via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Thu Feb 8 02:18:25 PST 2018


alex-t added inline comments.


================
Comment at: lib/Target/AMDGPU/AMDGPUISelLowering.cpp:786
+            RI->getRegClass(AMDGPU::VReg_256RegClassID)->contains(Reg) ||
+            RI->getRegClass(AMDGPU::VReg_512RegClassID)->contains(Reg);
+        }
----------------
rampitec wrote:
> I am afraid that is not true to say that VGPR is necessarily divergent.
That's not true.  Do we have a mean to detect that this is a splat vector?
If not I'd stay with conservative approach that consider all VGPRs divergent.
Alternatively we could add one more target hook to query for special VGPRs that are uniform.


https://reviews.llvm.org/D35267





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