[PATCH] D60852: Fix for bug 41512: lower INSERT_VECTOR_ELT(ZeroVec, 0, Elt) to SCALAR_TO_VECTOR(Elt) for all SSE flavors

[Sanjay Patel via Phabricator via llvm-commits]

spatel added a comment.

In D60852#1471492 <https://reviews.llvm.org/D60852#1471492>, @Serge_Preis wrote:

> In D60852#1471378 <https://reviews.llvm.org/D60852#1471378>, @RKSimon wrote:
>
> > Your test cases need to be a lot simpler - I'd recommend looking at buildvec-insertvec.ll and possibly adding your tests to that file instead of adding this new file.
>
>
> The problem is that in tiny kernel llvm behaves as I expect it to, while in a loop it underperforms: https://gcc.godbolt.org/z/PljujX -- compare Sum2 and Loop() code generation.
>  I will do my best to minimize the case.


If we are getting this right sometimes, then we might already have the transform that we want, but it is limited in some way that prevents getting the larger case.

I doubt that the loop itself is needed to demonstrate the problem because I see 'movd' codegen even with a loop as long as it is not unrolled.


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  https://reviews.llvm.org/D60852/new/

https://reviews.llvm.org/D60852