incr.comp.: Make cross-crate tracking for incr. comp. opt-in.
The current implementation of cross-crate dependency tracking can cause quite long compile times and high memory usage for some crates (see #39208 for example). This PR therefore makes that part of dependency tracking optional. Incremental compilation still works, it will only have very coarse dep-tracking for upstream crates.
r? @nikomatsakis
The standard implementations of Hasher have architecture-dependent
results when hashing integers. This causes problems when the hashes are
stored within metadata - metadata written by one host architecture can't
be read by another.
To fix that, implement an architecture-independent StableHasher and use
it in all places an architecture-independent hasher is needed.
Fixes#38177.
add a `-Z incremental-dump-hash` flag
This causes us to dump a bunch of has information to stdout that can be
useful in tracking down incremental compilation invalidations,
particularly across crates.
This causes us to dump a bunch of has information to stdout that can be
useful in tracking down incremental compilation invalidations,
particularly across crates.
Before this PR, type names could depend on the cratenum being used
for a given crate and also on the source location of closures.
Both are undesirable for incremental compilation where we cache
LLVM IR and don't want it to depend on formatting or in which
order crates are loaded.
This commit is intended to be backported to the 1.13 branch, and works with the
following APIs:
Stabilized
* `i32::checked_abs`
* `i32::wrapping_abs`
* `i32::overflowing_abs`
* `RefCell::try_borrow`
* `RefCell::try_borrow_mut`
* `DefaultHasher`
* `DefaultHasher::new`
* `DefaultHasher::default`
Deprecated
* `BinaryHeap::push_pop`
* `BinaryHeap::replace`
* `SipHash13`
* `SipHash24`
* `SipHasher` - use `DefaultHasher` instead in the `std::collections::hash_map`
module
Closes#28147Closes#34767Closes#35057Closes#35070
Implement synchronization scheme for incr. comp. directory
This PR implements a copy-on-write-based synchronization scheme for the incremental compilation cache directory. For technical details, see the documentation at the beginning of `rustc_incremental/persist/fs.rs`.
The PR contains unit tests for some functions but for testing whether the scheme properly handles races, a more elaborate test setup would be needed. It would probably involve a small tool that allows to manipulate the incremental compilation directory in a controlled way and then letting a compiler instance run against directories in different states. I don't know if it's worth the trouble of adding another test category to `compiletest`, but I'd be happy to do so.
Fixes#32754Fixes#34957
