[llvm] [SLP][TTI]Improve detection of the insert-subvector pattern for SLP. (PR #74749)

[Alexey Bataev via llvm-commits]

alexey-bataev wrote:

> Could we not improve ShuffleVectorInst::isInsertSubvectorMask directly instead?

Sorry, did not quite understand. You mean do the changes in ShuffleVectorInst::isInsertSubvectorMask? Unfortunately, no. Currently improveShuffleKindFromMask just does not provide correct type/subtype at all, so even changing ShuffleVectorInst::isInsertSubvectorMask won't help.

https://github.com/llvm/llvm-project/pull/74749