8e500099b3
* x64: Refactor sextend/uextend rules
Move much of the meaty logic from these lowering rules into the
`extend_to_gpr` helper to benefit other callers of `extend_to_gpr` to
elide instructions. This additionally simplifies `sextend` and `uextend`
lowerings to rely on optimizations happening within the `extend_to_gpr`
helper.
* x64: Skip `uextend` for `pextr{b,w}` instructions
These instructions are documented as automatically zeroing the upper
bits so `uextend` operations can be skipped. This slightly improves
codegen for the wasm `i{8x16,16x8}.extract_lane_u` instructions, for
example.
* Modernize an extractor pattern
* Trim some superfluous match clauses
Additionally rejigger priorities to be "mostly default" now.
* Refactor 32-to-64 predicate to a helper
Also adjust the pattern matched in the `extend_to_gpr` helper.
* Slightly refactor pextr{b,w} case
* Review comments
This crate contains the core Cranelift code generator. It translates code from an intermediate representation into executable machine code.