[PATCH] D149893: Rewrite LSV to handle longer chains.

Thu May 18 04:23:38 PDT 2023

arsenm added inline comments.

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Comment at: llvm/lib/Transforms/Vectorize/LoadStoreVectorizer.cpp:805
+      // existing tests.  This isn't *so* bad, because at most we align to 4
+      // bytes (current value of StackAdjustedAlignment).
+      //
----------------
jlebar wrote:
> barannikov88 wrote:
> > Does DL.getStackAlign() instead of 4 cause many negative differences in tests?
> > 
> DL.getStackAlignment() assert-fails on x86, nvptx, and amdgpu:
> 
> llvm::DataLayout::getStackAlignment() const: StackNaturalAlign && "StackNaturalAlign must be defined"
> 
> Not sure what's going on, but I don't think this is a windmill I want to tilt at in this patch.
For AMDGPU we definitely do not want to promote stack objects above 4 alignment. We should in fact have optmizations to under-align any stack values to 4 as long as the address isn't captured

Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D149893/new/

https://reviews.llvm.org/D149893