llvm-project

a88498f0 - [SLP]Skip buildvector tree, if all scalars are used externally and remain scalar

[SLP]Skip buildvector tree, if all scalars are used externally and remain scalar If the buildvector is going to be vector with threshold cost < 0 and all buildvector scalars are externally used and remain scalar, such a tree should not be vectorized, it may lead to a compiler hang because same scalars remain in the function and will be vectorized once again. Fixes #172609