[PATCH] D82961: [Scalarizer] Variable insert handling (PR46524)

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added inline comments.


================
Comment at: llvm/lib/Transforms/Scalar/Scalarizer.cpp:759
+  if (isa<Constant>(InsIdx))
+    return false;
+
----------------
bjope wrote:
> jdoerfert wrote:
> > I do not understand why we skip constant indices. 
> I don't know exactly, but Scalarizer is sometimes creating such instructions itself when a vector still is needed.
> 
> (Downstream we have hacked the scalarizer to keep vector load/stores (typically loading/storing to a register pair/quad). But artithmetics etc needs to be scalarized. So there are typically lots of insertelement/extractelement instructions around to glue things together after running the scalarizer.)
I mean, why shouldn't we skip them.
I'm not sure replacing constant extract with n constant extracts+select is better.


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  https://reviews.llvm.org/D82961/new/

https://reviews.llvm.org/D82961