llvm-project

19595357 - [X86] combineAdd - remove unnecessary add(a,concat(vpmaddwd(x,y),vpmaddwd(z,w))) -> vpdpwssd(a,concat(x,z),concat(y,w)) fold (#209838)

[X86] combineAdd - remove unnecessary add(a,concat(vpmaddwd(x,y),vpmaddwd(z,w))) -> vpdpwssd(a,concat(x,z),concat(y,w)) fold (#209838) We already handle vpmaddwd concatenation in combineConcatVectorOps - but 512-bit vpmaddwd is only available on BWI targets, which was missing from the tests Technically if there's a target that has AVX512VNNI but not BWI, then this fold would be useful, but there's no such target and there's a limit to "what if" optimisations we really need. A small attempt at cleaning out some not very useful code from X86ISelLowering.cpp - I'm intending to do a lot more of this for 24.x / #143088