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The `vreg_def_blockparam` and `vreg_def_inst` fields on CFGInfo are only used in `validate_ssa`, which in turn is only used in the ssagen fuzz target. Since these fields are never read in normal usage, initializing them is entirely wasted effort. According to valgrind/DHAT, when running `wasmtime compile` on the Sightglass Spidermonkey benchmark, removing these fields saves about 100M instructions, 23k heap allocations totalling 40MiB, and 47MiB of writes to the heap.
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.