Improve the forcing/promotion functions in `DepKindVTable`
This is a bundle of changes to the two function pointers in `DepKindVTable` that are responsible for forcing dep nodes, or promoting disk-cached values from the previous session into memory.
The perf improvements to incr-unchanged and incr-patched are likely from skipping more of the “promotion” plumbing for queries that never cache to disk.
Clean up `QueryVTable::hash_result` into `hash_value_fn`
This PR:
- Renames the query vtable field `hash_result` to `hash_value_fn`
- Removes the unhelpful `HashResult` type alias, which was hiding an important layer of `Option`
- Replaces the cryptic `hash_result!` helper macro with a more straightforward `if_no_hash!` helper, in line with other modifier-checking macros
- Renames a few identifiers to refer to a query's return value as `value`
There should be no change to compiler behaviour.
r? nnethercote (or compiler)
Remove query function arrays
`define_queries!` produces four arrays of function pointers, which other functions iterate over. These aren't actually necessary.
r? @petrochenkov
This commit:
- Renames the query vtable field `hash_result` to `hash_value_fn`
- Removes the unhelpful `HashResult` type alias, which was hiding an
important layer of `Option`
- Replaces the cryptic `hash_result!` helper macro with a more straightforward
`if_no_hash!` helper, in line with other modifier-checking macros
- Renames a few identifiers to refer to a query's return value as `value`
Currently `gather_active_jobs` and `gather_active_jobs_inner` do some of
the work each. This commit changes things so that `gather_active_jobs`
is just a thin wrapper around `gather_active_jobs_inner`. This paves the
way for removing `gather_active_jobs` in the next commit.
`QuerySystem` has these fields:
```
pub states: QueryStates<'tcx>,
pub caches: QueryCaches<'tcx>,
pub query_vtables: PerQueryVTables<'tcx>,
```
Each one has an entry for each query.
Some methods that take a query-specific `QueryVTable` need to access the
corresponding query-specific states and/or caches. So `QueryVTable`
stores the *byte offset* to the relevant fields within `states` and
`caches`, and uses that to (with `unsafe`) access the fields. This is
bizarre, and I hope it made sense in the past when the code was
structured differently.
This commit moves `QueryState` and `QueryCache` inside `QueryVTable`. As
a result, the query-specific states and/or caches are directly
accessible, and no unsafe offset computations are required. Much simpler
and more normal. Also, `QueryCaches` and `QueryStates` are no longer
needed, which makes `define_callbacks!` a bit simpler.
The commit also rename the fields and their getters to `states` and
`caches`.
`SemiDynamicQueryDispatcher` is just a `QueryVTable` wrapper with an
additional `const FLAGS: QueryFlags` generic parameter that contains
three booleans. This arrangement exists as a performance optimization.
But the performance effects are very small and it adds quite a bit of
complexity to an already overly-complex part of the codebase. If it
didn't exist and somebody proposed adding it and asked me to review, I
almost certainly wouldn't approve it.
This commit removes it. The three booleans in `QueryFlags` are moved
into `QueryVTable` The non-trivial methods of
`SemiDynamicQueryDispatcher` become methods of `QueryVTable`.
This struct was only wrapping `TyCtxt` in order to implement traits that
were removed by RUST-152636.
This commit also slightly simplifies the signature of `execute_job_incr`, by
having it call `tcx.dep_graph.data()` internally.
By removing the generic `D` parameter from `DepGraph`, `DepGraphData`,
`CurrentDepGraph`, `SerializedDepGraph`, `SerializedNodeHeader`, and
`EncoderState`.
Most of the files within the `dep_graph` module can be moved wholesale
into `rustc_middle`. But two of them (`mod.rs` and `dep_node.rs`) have
the same name as existing files in `rustc_middle`, so for those I just
copied the contents into the existing files.
The commit also moves `QueryContext` and `incremental_verify_ich*`
because they are tightly intertwined with the dep graph code. And a
couple of error structs moved as well.
This includes the types `QueryInfo`, `QueryJob`, `QueryJobId`,
`QueryWaiter`, `QueryLatch`, and `QueryLatchInfo`.
`CycleError` and `QueryStack*` had to come along too, due to type
interdependencies. The `QueryStack*` types are put into a new submodule
`rustc_middle::query::stack`.
Clarify names of `QueryVTable` functions for "executing" a query
In the query system, there are several layers of functions involved in “executing” a query, with very different responsibilities at each layer, making it important to be able to tell them apart.
This PR renames two of the function pointers in `QueryVTable`, along with their associated helper functions, to hopefully do a better job of indicating what their actual responsibilities are.
r? nnethercote
The latter is a new module.
As well as the code motion, some other changes were required.
- `QueryJobId` methods became free functions so they could move while
`QueryJobId` itself stayed put. This was so `QueryMap` and
`QueryJobInfo` could be moved.
- Some visibilities in `rustc_query_system` required changing.
- `collect_active_jobs_from_all_queries` is no longer required in `trait
QueryContext`.
This value is a previously-computed hash of the key, so it makes sense to
bundle it with the key inside the guard, since the guard will need it on
completion anyway.
It existed only to bridge the divide between `rustc_query_system` and
`rustc_query_impl`. But enough pieces have been moved from the former to
the latter that the trait is no longer needed. Less indirection and
abstraction makes the code easier to understand.
The previous commit moved some code from `rustc_query_system`, which
doesn't have access to `TyCtxt` and `QueryCtxt`, to `rustc_query_impl`,
which does. We can now remove quite a bit of indirection.
- Three methods in `trait QueryContext` are no longer needed
(`next_job_id`, `current_query_job`, `start_query`). As a result,
`QueryCtxt`'s trait impls of these methods are changed to inherent
methods.
- `qcx: Q::Qcx` parameters are simplified to `qcx: QueryCtxt<'tcx>`.
- `*qcx.dep_context()` occurrences are simplified to `qcx.tcx`, and
things like `qcx.dep_context().profiler()` become `qcx.tcx.prof`.
- `DepGraphData<<Q::Qcx as HasDepContext>::Deps>` becomes
`DepGraphData<DepsType>`.
In short, various layers of indirection and abstraction are cut away.
The resulting code is simpler, more concrete, and easier to understand.
It's a good demonstration of the benefits of eliminating
`rustc_query_system`, and there will be more to come.
[Note: this commit conceptually moves 75% of a file to another location,
and leaves 25% of it behind. It's impossible to preserve all the git
history. To preserve git history of the moved 75%, in this commit we
rename the file and remove the 25% from it, leaving the code in an
incomplete (uncompilable) state. In the next commit we add back the
25% in the old location.]
We are in the process of eliminating `rustc_query_system`. Chunks of it
are unused by `rustc_middle`, and so can be moved into
`rustc_query_impl`. This commit does some of that.
Mostly it's just moving code from one file to a new file. There are a
couple of non-trivial changes.
- `QueryState` and `ActiveKeyStatus` must remain in `rustc_query_system`
because they are used by `rustc_middle`. But their inherent methods
are not used by `rustc_middle`. So these methods are moved and
converted to free functions.
- The visibility of some things must increase. This includes `DepGraphData`
and some of its methods, which are now used in `rustc_query_impl`.
This is a bit annoying but seems hard to avoid.
What little is left behind in
`compiler/rustc_query_system/src/query/plumbing.rs` will be able to
moved into `rustc_query_impl` or `rustc_middle` in the future.
Nicholas Nethercote