[PATCH] D26066: [PowerPC] Improvements for BUILD_VECTOR Vol. 4

Nemanja Ivanovic via llvm-commits llvm-commits at lists.llvm.org
Fri Oct 28 11:30:10 PDT 2016

nemanjai added a comment.

In https://reviews.llvm.org/D26066#582220, @amehsan wrote:

> In https://reviews.llvm.org/D26066#581855, @nemanjai wrote:
> > Here are some examples of terrible code gen currently (rather than providing code, I'm just illustrating these with pseudo-SDAG nodes):
> Could you also comment on what is your process for identifying problematic patterns that have been addressed in these patches?

Yeah, when I was implementing some of the https://reviews.llvm.org/P9 instructions that naturally fit the BUILD_VECTOR nodes, I realized that we produce poor code for some patterns. I wanted to see how bad this situation is so I wrote the C test case that is added as a comment to `build-vector-tests.ll` and examined the assembly. Then I picked off the patterns that produce poor code and fixed them one by one.



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