1f915bb9b6
* validate_ssa: Check def uniqueness first I had trouble understanding `validate_ssa`, so this changes the division of work to establish one invariant at a time: - First, check that no VReg is defined in more than one place, and record which block it's defined in. - Second, check that each use refers to a VReg that was defined either earlier in the same block, or in a block dominating it. I'm also enhancing the validation to check that every VReg use is in an instruction that is strictly later than its def. Previously, an earlier operand in the same instruction would also be considered a valid def, but that isn't actually legal in SSA. * Address review comments
regalloc2: another register allocator
This is a register allocator that started life as, and is about 50% still, a port of IonMonkey's backtracking register allocator to Rust. In many regards, it has been generalized, optimized, and improved since the initial port, and now supports both SSA and non-SSA use-cases.
In addition, it contains substantial amounts of testing infrastructure (fuzzing harnesses and checkers) that does not exist in the original IonMonkey allocator.
See the design overview for (much!) more detail on how the allocator works.
License
This crate is licensed under the Apache 2.0 License with LLVM
Exception. This license text can be found in the file LICENSE.
Parts of the code are derived from regalloc.rs: in particular,
src/checker.rs and src/domtree.rs. This crate has the same license
as regalloc.rs, so the license on these files does not differ.