e8881b2cc0
This PR makes use of the new implicit-conversion feature of the ISLE DSL that was introduced in #3807 in order to make the lowering rules significantly simpler and more concise. The basic idea is to eliminate the repetitive and mechanical use of terms that convert from one type to another when there is only one real way to do the conversion -- for example, to go from a `WritableReg` to a `Reg`, the only sensible way is to use `writable_reg_to_reg`. This PR generally takes any term of the form "A_to_B" and makes it an automatic conversion, as well as some others that are similar in spirit. The notable exception to the pure-value-convsion category is the `put_in_reg` family of operations, which actually do have side-effects. However, as noted in the doc additions in #3807, this is fine as long as the side-effects are idempotent. And on balance, making `put_in_reg` automatic is a significant clarity win -- together with other operand converters, it enables rules like: ``` ;; Add two registers. (rule (lower (has_type (fits_in_64 ty) (iadd x y))) (add ty x y)) ``` There may be other converters that we could define to make the rules even simpler; we can make such improvements as we think of them, but this should be a good start!
This crate contains the core Cranelift code generator. It translates code from an intermediate representation into executable machine code.