When -Z profile is passed, the GCDAProfiling LLVM pass is added
to the pipeline, which uses debug information to instrument the IR.
After compiling with -Z profile, the $(OUT_DIR)/$(CRATE_NAME).gcno
file is created, containing initial profiling information.
After running the program built, the $(OUT_DIR)/$(CRATE_NAME).gcda
file is created, containing branch counters.
The created *.gcno and *.gcda files can be processed using
the "llvm-cov gcov" and "lcov" tools. The profiling data LLVM
generates does not faithfully follow the GCC's format for *.gcno
and *.gcda files, and so it will probably not work with other tools
(such as gcov itself) that consume these files.
this avoids parsing item attributes on each call to `item_attrs`, which takes
off 33% (!) of translation time and 50% (!) of trans-item collection time.
ICH: Replace old, transitive metadata hashing with direct hashing approach.
This PR replaces the old crate metadata hashing strategy with a new one that directly (but stably) hashes all values we encode into the metadata. Previously we would track what data got accessed during metadata encoding and then hash the input nodes (HIR and upstream metadata) that were transitively reachable from the accessed data. While this strategy was sound, it had two major downsides:
1. It was susceptible to generating false positives, i.e. some input node might have changed without actually affecting the content of the metadata. That metadata entry would still show up as changed.
2. It was susceptible to quadratic blow-up when many metadata nodes shared the same input nodes, which would then get hashed over and over again.
The new method does not have these disadvantages and it's also a first step towards caching more intermediate results in the compiler.
Metadata hashing/cross-crate incremental compilation is still kept behind the `-Zincremental-cc` flag even after this PR. Once the new method has proven itself with more tests, we can remove the flag and enable cross-crate support by default again.
r? @nikomatsakis
cc @rust-lang/compiler
remove unnecessary tasks
Remove various unnecessary tasks. All of these are "always execute" tasks that don't do any writes to tracked state (or else an assert would trigger, anyhow). In some cases, they issue lints or errors, but we''ll deal with that -- and anyway side-effects outside of a task don't cause problems for anything that I can see.
The one non-trivial refactoring here is the borrowck conversion, which adds the requirement to go from a `DefId` to a `BodyId`. I tried to make a useful helper here.
r? @eddyb
cc #40746
cc @cramertj @michaelwoerister
Instead of collecting all potential inputs to some metadata entry and
hashing those, we directly hash the values we are storing in metadata.
This is more accurate and doesn't suffer from quadratic blow-up when
many entries have the same dependencies.
Handle DefPath hashing centrally as part of DefPathTable (+ save work during SVH calculation)
In almost all cases where we construct a `DefPath`, we just hash it and throw it away again immediately.
With this PR, the compiler will immediately compute and store the hash for each `DefPath` as it is allocated. This way we
+ can get rid of any subsequent `DefPath` hash caching (e.g. the `DefPathHashes`),
+ don't need to allocate a transient `Vec` for holding the `DefPath` (although I'm always surprised how little these small, dynamic allocations seem to hurt performance), and
+ we don't hash `DefPath` prefixes over and over again.
That last part is because we construct the hash for `prefix::foo` by hashing `(hash(prefix), foo)` instead of hashing every component of prefix.
The last commit of this PR is pretty neat, I think:
```
The SVH (Strict Version Hash) of a crate is currently computed
by hashing the ICHes (Incremental Computation Hashes) of the
crate's HIR. This is fine, expect that for incr. comp. we compute
two ICH values for each HIR item, one for the complete item and
one that just includes the item's interface. The two hashes are
are needed for dependency tracking but if we are compiling
non-incrementally and just need the ICH values for the SVH,
one of them is enough, giving us the opportunity to save some
work in this case.
```
r? @nikomatsakis
This PR depends on https://github.com/rust-lang/rust/pull/40878 to be merged first (you can ignore the first commit for reviewing, that's just https://github.com/rust-lang/rust/pull/40878).
On demandify reachability
cc https://github.com/rust-lang/rust/issues/40746
I tried following this guidance from #40746:
> The following tasks currently execute before a tcx is built, but they could be easily converted into queries that are requested after tcx is built. The main reason they are the way they are was to avoid a gratuitious refcell (but using the refcell map seems fine)...
but the result of moving `region_maps` out of `TyCtxt` and into a query caused a lot of churn, and seems like it could potentially result in a rather large performance hit, since it means a dep-graph lookup on every use of `region_maps` (rather than just a field access). Possibly `TyCtxt` could store a `RefCell<Option<RegionMap>>` internally and use that to prevent repeat lookups, but that feels like it's duplicating the work of the dep-graph. @nikomatsakis What did you have in mind for this?
Remove internal liblog
This commit deletes the internal liblog in favor of the implementation that
lives on crates.io. Similarly it's also setting a convention for adding crates
to the compiler. The main restriction right now is that we want compiler
implementation details to be unreachable from normal Rust code (e.g. requires a
feature), and by default everything in the sysroot is reachable via `extern
crate`.
The proposal here is to require that crates pulled in have these lines in their
`src/lib.rs`:
#![cfg_attr(rustbuild, feature(staged_api, rustc_private))]
#![cfg_attr(rustbuild, unstable(feature = "rustc_private", issue = "27812"))]
This'll mean that by default they're not using these attributes but when
compiled as part of the compiler they do a few things:
* Mark themselves as entirely unstable via the `staged_api` feature and the
`#![unstable]` attribute.
* Allow usage of other unstable crates via `feature(rustc_private)` which is
required if the crate relies on any other crates to compile (other than std).
This commit deletes the internal liblog in favor of the implementation that
lives on crates.io. Similarly it's also setting a convention for adding crates
to the compiler. The main restriction right now is that we want compiler
implementation details to be unreachable from normal Rust code (e.g. requires a
feature), and by default everything in the sysroot is reachable via `extern
crate`.
The proposal here is to require that crates pulled in have these lines in their
`src/lib.rs`:
#![cfg_attr(rustbuild, feature(staged_api, rustc_private))]
#![cfg_attr(rustbuild, unstable(feature = "rustc_private", issue = "27812"))]
This'll mean that by default they're not using these attributes but when
compiled as part of the compiler they do a few things:
* Mark themselves as entirely unstable via the `staged_api` feature and the
`#![unstable]` attribute.
* Allow usage of other unstable crates via `feature(rustc_private)` which is
required if the crate relies on any other crates to compile (other than std).
On-demandify associated item retrieval
Part of #40614.
I also started converting `adt_def`, but I decided to open a PR with just this bit first to make sure I'm going about this correctly.
r? @nikomatsakis
Some preparations for directly computing the ICH of crate-metadata.
This PR contains some small fixes in preparation for direct metadata hashing. It mostly just moves stuff into places where it will be needed (making the module structure slightly cleaner along the way) and it fixes some omissions in the MIR region eraser.
r? @nikomatsakis
syntax: add `ast::ItemKind::MacroDef`, simplify hygiene info
This PR
- adds a new variant `MacroDef` to `ast::ItemKind` for `macro_rules!` and eventually `macro` items,
- [breaking-change] forbids macro defs without a name (`macro_rules! { () => {} }` compiles today),
- removes `ast::MacroDef`, and
- no longer uses `Mark` and `Invocation` to identify and characterize macro definitions.
- We used to apply (at least) two `Mark`s to an expanded identifier's `SyntaxContext` -- the definition mark(s) and the expansion mark(s). We now only apply the latter.
r? @nrc
[MIR] Implement Inlining
Fairly basic implementation of inlining for MIR. Uses conservative
heuristics for inlining.
Doesn't handle a number of cases, but can be extended later. This is basically the same as the previous inlining PR, but without the span-related changes (as the bugs it was dealing with have since been fixed).
/cc @rust-lang/compiler
rustc: Exit quickly on only `--emit dep-info`
This commit alters the compiler to exit quickly if the only output being emitted
is `dep-info`, which doesn't need a lot of other information to generate.
Closes#40328
This commit alters the compiler to exit quickly if the only output being emitted
is `dep-info`, which doesn't need a lot of other information to generate.
Closes#40328
In recent months there have been a few different people investigating how to make a plugin that
registers a MIR-pass – one that isn’t intended to be eventually merged into rustc proper.
The interface to register MIR passes was added primarily for miri (& later was
found to make prototyping of rustc-proper MIR passes a tiny bit faster). Since miri does not use
this interface anymore it seems like a good time to remove this "feature".
For prototyping purposes a similar interface can be added by developers themselves in their custom
rustc build.
whitequark
Ariel Ben-Yehuda
Ariel Ben-Yehuda
Niko Matsakis
Eduard-Mihai Burtescu
Tim Neumann
Michael Woerister
Corey Farwell
bors
Simonas Kazlauskas
Taylor Cramer
Jeffrey Seyfried
Alex Crichton
Nick Cameron
Jake Goulding
James Miller
Josh Driver
Alex Burka
king6cong