Using a pure spin lock for a critical section in a preemptable thread
is always wrong, however short the critical section may be. The thread
might be preempted, which will cause all other threads to hammer
busily at the core for the whole quant. Moreover, if threads have
different priorities, this might lead to a priority inversion problem
and a deadlock. More generally, a spinlock is not more efficient than
a well-written mutex, which typically does several spin iterations at
the start anyway.
The advise about UP vs SMP is also irrelevant in the context of
preemptive threads.
Lint overflowing integer casts in const prop
This extends the invalid cases we catch in const prop to include
overflowing integer casts using the same machinery as the overflowing
binary and unary operation logic.
r? @oli-obk
Revert parts of #66405.
Because PR #66405 caused major performance regressions in some cases.
That PR had five commits, two of which affected performance, and three
of which were refactorings. This change undoes the performance-affecting
changes, while keeping the refactorings in place.
Fixes#67454.
r? @nikomatsakis
Because it caused major performance regressions in some cases.
That PR had five commits, two of which affected performance, and three
of which were refactorings. This change undoes the performance-affecting
changes, while keeping the refactorings in place.
Fixes#67454.
Use function attribute "frame-pointer" instead of "no-frame-pointer-elim"
LLVM 8 ([D56351](http://reviews.llvm.org/D56351)) introduced "frame-pointer". In LLVM 10 (D71863),
"no-frame-pointer-elim"/"no-frame-pointer-elim-non-leaf" will be
ignored.
-----
In the LLVM monorepo, run `git show origin/release/8.x:llvm/lib/CodeGen/TargetOptionsImpl.cpp` to see that `"frame-pointer"` is available since LLVM 8.
parser: reduce diversity in error handling mechanisms
Instead of having e.g. `span_err`, `fatal`, etc., we prefer to move towards uniformly using `struct_span_err` thus making it harder to emit fatal and/or unstructured diagnostics.
This PR also de-fatalizes some diagnostics.
r? @estebank
Extract `rustc_ast_lowering` crate from `rustc`
Working towards https://github.com/rust-lang/rust/issues/65031.
This PR moves `src/librustc/hir/lowering{/, .rs}` to its own crate (`librustc_ast_lowering`) which is very self-contained (only `fn lower_crate` and `trait Resolver` are exposed).
r? @Mark-Simulacrum
Support `-Z ui-testing=yes/no`
`ui-testing` is now a boolean option (`-Z ui-testing=yes/no`) and can be specified multiple times with later values overriding earlier values (`-Z ui-testing=yes -Z ui-testing=no` == `-Z ui-testing=no`), so it can be set in a hierarchical way, e.g. UI testing infra may enable it by default with specific tests being able to opt-out.
This way we can remove the special opt-out support from `compiletest`.
Inspired by https://github.com/rust-lang/rust/pull/67709.
Allocate HIR on an arena 4/4
This is the fourth and last PR in the series started by #66931, #66936 and #66942.
The last commits should compile on their own.
The difference with the previous PR is given by https://github.com/cjgillot/rust/compare/hirene-ty...hirene
A few more cleanups may be necessary, please tell me.
r? @eddyb like the other
cc @Zoxc
