[PATCH] D128252: [AMDGPU] VGPR to SGPR copies lowering

[Alexander via Phabricator via llvm-commits]

alex-t added inline comments.


================
Comment at: llvm/lib/Target/AMDGPU/SIFixSGPRCopies.cpp:1134
+      else
+        MIB.addReg(SrcReg);
+    } else {
----------------
rampitec wrote:
> What happens to 16 bit subregs?
VGPR to SGPR copies are inserted by InstrEmitter to adjust the VALU result to the SALU consumer.
The 16bits in VGPR result are packed and adjusted to the consumer by inserting the EXCTRACT_ELEMENT lowered in another place.
What kind of adjustment would you recommend if we have a 16bit VGPR source?
Zero-extend it to 32bit?



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  https://reviews.llvm.org/D128252/new/

https://reviews.llvm.org/D128252