Take MIR dataflow analyses by mutable reference
The main motivation here is any analysis requiring dynamically sized scratch memory to work. One concrete example would be pointer target tracking, where tracking the results of a dereference can result in multiple possible targets. This leads to processing multi-level dereferences requiring the ability to handle a changing number of potential targets per step. A (simplified) function for this would be `fn apply_deref(potential_targets: &mut Vec<Target>)` which would use the scratch space contained in the analysis to send arguments and receive the results.
The alternative to this would be to wrap everything in a `RefCell`, which is what `MaybeRequiresStorage` currently does. This comes with a small perf cost and loses the compiler's guarantee that we don't try to take multiple borrows at the same time.
For the implementation:
* `AnalysisResults` is an unfortunate requirement to avoid an unconstrained type parameter error.
* `CloneAnalysis` could just be `Clone` instead, but that would result in more work than is required to have multiple cursors over the same result set.
* `ResultsVisitor` now takes the results type on in each function as there's no other way to have access to the analysis without cloning it. This could use an associated type rather than a type parameter, but the current approach makes it easier to not care about the type when it's not necessary.
* `MaybeRequiresStorage` now no longer uses a `RefCell`, but the graphviz formatter now does. It could be removed, but that would require even more changes and doesn't really seem necessary.
Do `fix_*_builtin_expr` hacks on the writeback results
During writeback, we do `fix_{scalar,index}_builtin_expr` so that during MIR build we generate built-in MIR instructions instead of method calls for certain built-in arithmetic operations. We do this by checking the types of these built-in operations are scalar types, and remove the method def-id to essentially mark the operation as built-in and not "overloaded".
For lazy norm and the new trait solver, this is a problem, because we don't actually normalize all the types we end up seeing in the typeck results until they're copied over writeback's copy of the typeck results. To fix this, delay these fixup calls until after this normalization has been done.
This doesn't affect the old trait solver, but does simplify the code a bit IMO, since we can remove a few sets of calls to `resolve_vars_if_possible` and some `borrow_mut`s.
r? `@lcnr`
Don't hold the active queries lock while calling `make_query`
This moves the call to `make_query` outside the parts that holds the active queries lock in `try_collect_active_jobs`. This should help removed the deadlock and borrow panic that has been observed when printing the query stack during an ICE.
cc `@SparrowLii`
r? `@cjgillot`
Rollup of 9 pull requests
Successful merges:
- #112034 (Migrate `item_opaque_ty` to Askama)
- #112179 (Avoid passing --cpu-features when empty)
- #112309 (bootstrap: remove dependency `is-terminal`)
- #112388 (Migrate GUI colors test to original CSS color format)
- #112389 (Add a test for #105709)
- #112392 (Fix ICE for while loop with assignment condition with LHS place expr)
- #112394 (Remove accidental comment)
- #112396 (Track more diagnostics in `rustc_expand`)
- #112401 (Don't `use compile_error as print`)
r? `@ghost`
`@rustbot` modify labels: rollup
Don't `use compile_error as print`
I've spent **1.5 hours** debugging this while trying to compile #112400, if we use `compile_error!`, we should not just forward user input to it, but issue a reasonable error message.
The better solution would be to use a lint like `clippy::print_stdout`, but since we don't have clippy in CI, let's at least make the macro error better.
Also note that some functions called here actually do use `println` (see for example `print_type_sizes` function).
Removed use of iteration through a HashMap/HashSet in rustc_incremental and replaced with IndexMap/IndexSet
This allows for the `#[allow(rustc::potential_query_instability)]` in rustc_incremental to be removed, moving towards fixing #84447 (although a LOT more modules have to be changed to fully resolve it). Only HashMaps/HashSets that are being iterated through have been modified (although many structs and traits outside of rustc_incremental had to be modified as well, as they had fields/methods that involved a HashMap/HashSet that would be iterated through)
I'm making a PR for just 1 module changed to test for performance regressions and such, for future changes I'll either edit this PR to reflect additional modules being converted, or batch multiple modules of changes together and make a PR for each group of modules.
Avoid unwind across `extern "C"` in `thread_local::fast_local`
This is a minimal fix for #112285, in case we want a simple patch that can be easily to backported if that's desirable.
*(Note: I have another broader cleanup which I've mostly omitted from here to avoid clutter, except for the `Cell` change, which isn't needed to fix UB, but simplifies safety comments).*
The only tier-1 target that this occurs on in a way that seems likely to cause problems in practice linux-gnu, although I believe some folks care about that platform somewhat 😉. I'm unsure how big of an issue this is. I've seen stuff like this behave quite badly, but there's a number of reasons to think this might actually be "fine in practice".
I've hedged my bets and assumed we'll backport this at least to beta but my feeling is that there's not enough evidence this is a problem worth backporting further than that.
### More details
This issue seems to have existed since `thread_local!`'s `const` init functionality was added. It occurs if you have a `const`-initialized thread local for a type that `needs_drop`, the drop panics, and you're on a target with support for static thread locals. In this case, we will end up defining an `extern "C"` function in the user crate rather than in libstd, and because the user crate will not have `#![feature(c_unwind)]` enabled, their panic will not be caught by an auto-inserted abort guard.
In practice, the actual situation where problems are likely[^ub] is somewhat narrower.
On most targets with static thread locals, we manage the TLS dtor list by hand (for reentrancy reasons among others). In these cases, while the users code may panic, we're calling it inside our own `extern "C"` (or `extern "system"`) function, which seems to (at least in practice) catch the panic and convert it to an abort.
However, on a few targets, most notably linux-gnu with recent glibc (but also fuchsia and redox), a tls dtor registration mechanism exists which we can actually use directly, [`__cxa_thread_atexit_impl`](https://github.com/rust-lang/rust/blob/master/library/std/src/sys/unix/thread_local_dtor.rs#L26-L36).
This is the case that seems most likely to be a cause for concern, as now we're passing a function to the system library and panicking out of it in a case where there are may not be Rust frames above it on the call stack (since it's running thread shutdown), and even if there were, it may not be prepared to handle such unwinding. If that's the case, it'd be bad.
Is it? Dunno. The fact that it's a `__cxa_*` function makes me think they probably have considered that the callback could throw but I have no evidence here and it doesn't seem to be written down anywhere, so it's just a guess. (I would not be surprised if someone comes into this thread to tell me how definitely-bad-news it is).
That said, as I said, all this is actually UB! If this isn't a "technically UB but fine in practice", but all bets are off if this is the kind of thing we are telling LLVM about.
[^ub]: This is UB so take that with a grain of salt -- I'm absolutely making assumptions about how the UB will behave "in practice" here, which is almost certainly a mistake.
Avoid one `rustc` rebuild in the optimized build pipeline
This PR changes the optimized build pipeline to avoid one `rustc` rebuild, inspired by [this comment](https://github.com/rust-lang/rust/issues/112011#issuecomment-1564991175). This speeds up the pipeline by 5-10 minutes. After this change, we **no longer gather LLVM PGO profiles from compiling stage 2 of `rustc`**.
Now we build `rustc` two times (1x PGO instrumented, 1x PGO optimized) and LLVM three times (1x normal, 1x PGO instrumented, 1x PGO optimized). It should be possible to cache the normal LLVM build, but I'll leave that for another PR.
Force all native libraries to be statically linked when linking a static binary
Previously, `#[link]` without an explicit `kind = "static"` would confuse the linker and end up producing a dynamically linked library because of the `-Bdynamic` flag. However this binary would not work correctly anyways since it was linked with startup code for a static binary.
This PR solves this by forcing all native libraries to be statically linked when the output is a static binary that cannot link to dynamic libraries anyways.
Fixes#108878Fixes#102993
Michael Goulet