77ab99d3b0
* Cleanups to cranelift-frontend SSA construction * Encode sealed/undef_variables relationship in type A block can't have any undef_variables if it is sealed. It's useful to make that fact explicit in the types so that any time either value is used, it's clear that we should think about the other one too. In addition, encoding this fact in an enum type lets Rust apply an optimization that reduces the size of SSABlockData by 8 bytes, making it fit in a 64-byte cache line. I haven't taken the extra step of making SSABlockData be 64-byte aligned because 1) it doesn't seem to have a performance impact and b) doing so makes other structures quite a bit bigger. * Simplify finish_predecessors_lookup Using Vec::drain is more concise than a combination of iter().rev().take() followed by Vec::truncate. And in this case it doesn't matter what order we examine the results in, because we just want to know if they're all equal, so we might as well iterate forward instead of in reverse. There's no need for the ZeroOneOrMore enum. Instead, there are only two cases: either we have a single value to use for the variable (possibly synthesized as a constant zero), or we need to add a block parameter in every predecessor. Pre-filtering the results iterator to eliminate the sentinel makes it easy to identify how many distinct definitions this variable has. iter.next() indicates if there are any definitions at all, and then iter.all() is a clear way to express that we want to know if the remaining definitions are the same as the first one. * Simplify append_jump_argument * Avoid assigning default() into SecondaryMap This eliminates some redundant reads and writes. * cranelift-frontend: Construct with default() This eliminates a bunch of boilerplate in favor of a built in `derive` macro. Also I'm deleting an import that had the comment "FIXME: Remove in edition2021", which we've been using everywhere since April. * Fix tests
This crate provides a straightforward way to create a
Cranelift IR function and fill it with
instructions translated from another language. It contains an SSA construction
module that provides convenient methods for translating non-SSA variables into
SSA Cranelift IR values via use_var and def_var calls.