[VectorCombine][TTI] Prevent extract/ins rewrite to GEP (#150216)

Using GEP to index into a vector is not disallowed, but not recommended.
The SPIR-V backend needs to generate structured access into types, which
is impossible with an untyped GEP instruction unless we add more info to
the IR. Finding a solution is a work-in-progress, but in the meantime,
we'd like to reduce the amount of failures.

Preventing this optimizations from rewritting extract/insert
instructions into a GEP helps us lower more code to SPIR-V. This change
should be OK as it's only active when targeting SPIR-V and disabling a
non-recommended transformation.

Related to #145002

0 files changed, 0 insertions, 0 deletions