rework the queries for the MIR pipeline #41625
Merged
Commits on May 2, 2017
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Each MIR key is a DefId that has MIR associated with it
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simplify the MirPass traits and passes dramatically
Overall goal: reduce the amount of context a mir pass needs so that it resembles a query. - The hooks are no longer "threaded down" to the pass, but rather run automatically from the top-level (we also thread down the current pass number, so that the files are sorted better). - The hook now receives a *single* callback, rather than a callback per-MIR. - The traits are no longer lifetime parameters, which moved to the methods -- given that we required `for<'tcx>` objecs, there wasn't much point to that. - Several passes now store a `String` instead of a `&'l str` (again, no point).
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rewrite
Passesto have sets of passesAlso, store the completed set of passes in the tcx.
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The new setup is as follows. There is a pipeline of MIR passes that each run **per def-id** to optimize a particular function. You are intended to request MIR at whatever stage you need it. At the moment, there is only one stage you can request: - `optimized_mir(def_id)` This yields the final product. Internally, it pulls the MIR for the given def-id through a series of steps. Right now, these are still using an "interned ref-cell" but they are intended to "steal" from one another: - `mir_build` -- performs the initial construction for local MIR - `mir_pass_set` -- performs a suite of optimizations and transformations - `mir_pass` -- an individual optimization within a suite So, to construct the optimized MIR, we invoke: mir_pass_set((MIR_OPTIMIZED, def_id)) which will build up the final MIR. -
introduce idea of "stealable" MIR
This is a more principled version of the `RefCell` we were using before. We now allocate a `Steal<Mir<'tcx>>` for each intermediate MIR pass; when the next pass steals the entry, any later attempts to use it will panic (there is no way to *test* if MIR is stolen, you're just supposed to *know*).
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introduce
IntoKeyValuestrait to prepare for multi-queriesThe idea is that such queries will return `FxHashMap`
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convert the
inlinepass to use the new multi resultThis involves changing various details about that system, though the basic shape remains the same.
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support inlining by asking for optimizer mir for callees
I tested this with it enabled 100% of the time, and we were able to run mir-opt tests successfully.
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