This change adds support for lowering llvm.prefetch directly using
GlobalISel. Currently, llvm.prefetch falls back to SelectionDAG.
- Adds an AArch64-specific G_PREFETCH generic instruction, to be used where AArch64ISD::PREFETCH is used in SelectionDAG.
- Adds the GINodeEquiv so patterns are translated over to GlobalISel automatically.
- Corrects the AArch64Prefetch patterns to use a target immediate, which is needed to get the patterns to translate across correctly.
- Translates the SelectionDAG legalisation of the prefetch intrinsic into the corresponding GlobalISel legalisation.
Depends on D132042