de8d44d0e5
The `MachBuffer` applies a set of peephole-optimization rules to do branch threading, leverage fallthrough paths, eliminate empty blocks, and flip conditional branches where needed to make branches more efficient starting from naive always-branch-at-end-of-BB code. This works by applying the rules at every label-bind, which is equivalent to applying them at the end of every basic block, where branches are usually inserted. However, this misses one case: the end of the buffer! Currently we don't optimize any redundant or foldable branches at the very end of the machine code. This usually doesn't matter when the function ends in an epilogue with `ret` as the last instruction. However, when cold blocks exist, it can actually matter. Thanks to @mchesser for pointing out this issue in #4636.
This crate contains the core Cranelift code generator. It translates code from an intermediate representation into executable machine code.