This commit makes the following writing improvements:
- Removes the unnecessary `write_to_vec` function.
- Reduces the number of conditions per loop from 2 to 1.
- Avoids a mask and a shift on the final byte.
And the following reading improvements:
- Removes an unnecessary type annotation.
- Fixes a dangerous unchecked slice access. Imagine a slice `[0x80]` --
the current code will read past the end of the slice some number of
bytes. The bounds check at the end will subsequently trigger, unless
something bad (like a crash) happens first. The cost of doing bounds
check in the loop body is negligible.
- Avoids a mask on the final byte.
And the following improvements for both reading and writing:
- Changes `for` to `loop` for the loops, avoiding an unnecessary
condition on each iteration. This also removes the need for
`leb128_size`.
All of these changes give significant perf wins, up to 5%.
rustc_codegen_ssa: only "spill" SSA-like values to the stack for debuginfo.
This is an implementation of the idea described in https://github.com/rust-lang/rust/issues/68817#issuecomment-583719182.
In short, instead of debuginfo forcing otherwise-SSA-like MIR locals into `alloca`s, and requiring a `load` for each use (or two, for scalar pairs), the `alloca` is now *only* used for attaching debuginfo with `llvm.dbg.declare`: the `OperandRef` is stored to the `alloca`, but *never loaded* from it.
Outside of `debug_introduce_local`, nothing cares about the debuginfo-only `alloca`, and instead works with `OperandRef` the same as MIR locals without debuginfo before this PR.
This should have some of the benefits of `llvm.dbg.value`, while working today.
cc @nagisa @nikomatsakis
Changes:
````
Update jobserver.
Update tar.
Emit report on error with Ztimings.
Do not run `formats_source` if `rustfmt` is not available
Fix rebuild_sub_package_then_while_package on HFS.
Remove likely brittle test.
Install rustfmt for testing in CI
Fix build-std collisions.
Fix BuildScriptOutput when a build script is run multiple times.
Fix required-features using renamed dependencies.
Fix using global options before an alias.
Update changelog for 1.42.
Bump to 0.44.0.
Log rustfmt output if it fails; also do not check that rustfmt exists
Update pretty_env_logger requirement from 0.3 to 0.4
Swap std::sync::mpsc channel with crossbeam_channel
Fix tests on Linux/MacOS
Fix typo.
Add tests
Deduplicate warnings about missing rustfmt
Log entry 2: first implementation
Refactor code
Stabilize config-profile.
Log entry 1
Format code
Remove tempdir after install
Keep existing package with git install
Use non-ephemeral workspace
Test that git install reads virtual manifest
Fix failing test
Search for root manifest with ephemeral workspaces
Support out-dir in build section of Cargo configuration file
````
This repr-hint makes a struct/enum hide any niche within from its
surrounding type-construction context.
It is meant (at least initially) as an implementation detail for
resolving issue 68303. We will not stabilize the repr-hint unless
someone finds motivation for doing so.
(So, declaration of `no_niche` feature lives in section of file
where other internal implementation details are grouped, and
deliberately leaves out the tracking issue number.)
incorporated review feedback, and fixed post-rebase.
change an instance of span_bug() to struct_span_err() to avoid ICE
After #67148, the `span_bug()` in `parse_ty_tuple_or_parens()` is reachable because `parse_paren_comma_seq()` can return an `Ok()` even in cases where it encounters an error.
This pull request prevents an ICE in such cases by replacing the `span_bug()` with `struct_span_error()`.
Fixes#68890.
