This patch exploits the prefixed load and store instructions utilizing the
refactored load/store implementation introduced in D93370.
Prefixed load and store instructions are emitted whenever we are loading or
storing a value with an offset that fits into a 34-bit signed immediate.
Patterns for the prefixed load and stores are added in this patch, as well as
the implementation that detects when we are loading and storing a value with an
offset that fits in 34-bits.
Differential Revision: https://reviews.llvm.org/D96075
Amy Kwan