Use -fvisibility=hidden for libunwind
We don't want to export any symbols from Rust's version of libunwind
as these may collide with other copies of libunwind e.g. when linking
Rust staticlib together C/C++ libraries that have their own version.
Use the `impls` module to import pre-existing dataflow analyses
Currently, existing analyses live in the same module as the traits and types used to define new dataflow analyses. This muddles the [documentation for the `dataflow` module](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_mir/dataflow/index.html). After this PR, `dataflow::impls` will refer to concrete dataflow analyses, and `dataflow` to the generic interface.
x.py: Give a more helpful error message if curl isn't installed
Before:
```
Updating only changed submodules
Submodules updated in 0.01 seconds
Traceback (most recent call last):
File "./x.py", line 11, in <module>
bootstrap.main()
...
File "/home/joshua/src/rust/src/bootstrap/bootstrap.py", line 137, in run
ret = subprocess.Popen(args, **kwargs)
File "/usr/lib/python2.7/subprocess.py", line 394, in __init__
errread, errwrite)
File "/usr/lib/python2.7/subprocess.py", line 1047, in _execute_child
raise child_exception
OSError: [Errno 2] No such file or directory
```
After:
```
Updating only changed submodules
Submodules updated in 0.01 seconds
spurious failure, trying again
spurious failure, trying again
spurious failure, trying again
spurious failure, trying again
failed to run: curl -s -y 30 -Y 10 --connect-timeout 30 --retry 3 -Sf -o /tmp/tmpSWF21P.sha256 https://static.rust-lang.org/dist/2020-04-22/rust-std-beta-x86_64-unknown-linux-gnu.tar.gz.sha256: [Errno 2] No such file or directory
Build completed unsuccessfully in 0:00:00
```
Define UB in float-to-int casts to saturate
This closes#10184 by defining the behavior there to saturate infinities and values exceeding the integral range (on the lower or upper end). `NaN` is sent to zero.
- Round to zero, and representable values cast directly.
- `NaN` goes to 0
- Values beyond the limits of the type are saturated to the "nearest value"
(essentially rounding to zero, in some sense) in the integral type, so e.g.
`f32::INFINITY` would go to `{u,i}N::MAX.`
Rollup of 6 pull requests
Successful merges:
- #71510 (Btreemap iter intertwined)
- #71727 (SipHasher with keys initialized to 0 should just use new())
- #71889 (Explain our RwLock implementation)
- #71905 (Add command aliases from Cargo to x.py commands)
- #71914 (Backport 1.43.1 release notes to master)
- #71921 (explain the types used in the open64 call)
Failed merges:
r? @ghost
explain the types used in the open64 call
Fixes https://github.com/rust-lang/rust/issues/71915, where I learned about this quirk. I don't actually know what I am talking about here. ;)
Btreemap iter intertwined
3 commits:
1. Introduced benchmarks for `BTreeMap::iter()`. Benchmarks named `iter_20` were of the whole iteration process, so I renamed them. Also the benchmarks of `range` that I wrote earlier weren't very good. I included an (awkwardly named) one that compares `iter()` to `range(..)` on the same set, because the contrast is surprising:
```
name ns/iter
btree::map::range_unbounded_unbounded 28,176
btree::map::range_unbounded_vs_iter 89,369
```
Both dig up the same pair of leaf edges. `range(..)` also checks that some keys are correctly ordered, the only thing `iter()` does more is to copy the map's length.
2. Slightly refactoring the code to what I find more readable (not in chronological order of discovery), boosts performance:
```
>cargo-benchcmp.exe benchcmp a1 a2 --threshold 5
name a1 ns/iter a2 ns/iter diff ns/iter diff % speedup
btree::map::find_rand_100 18 17 -1 -5.56% x 1.06
btree::map::first_and_last_10k 64 71 7 10.94% x 0.90
btree::map::iter_0 2,939 2,209 -730 -24.84% x 1.33
btree::map::iter_1 6,845 2,696 -4,149 -60.61% x 2.54
btree::map::iter_100 8,556 3,672 -4,884 -57.08% x 2.33
btree::map::iter_10k 9,292 5,884 -3,408 -36.68% x 1.58
btree::map::iter_1m 10,268 6,510 -3,758 -36.60% x 1.58
btree::map::iteration_mut_100000 478,575 453,050 -25,525 -5.33% x 1.06
btree::map::range_unbounded_unbounded 28,176 36,169 7,993 28.37% x 0.78
btree::map::range_unbounded_vs_iter 89,369 38,290 -51,079 -57.16% x 2.33
btree::set::clone_100_and_remove_all 4,801 4,245 -556 -11.58% x 1.13
btree::set::clone_10k_and_remove_all 529,450 496,030 -33,420 -6.31% x 1.07
```
But you can tell from the `range_unbounded_*` lines that, despite an unwarranted, vengeful attack on the range_unbounded_unbounded benchmark, this change still doesn't allow `iter()` to catch up with `range(..)`.
3. I guess that `range(..)` copes so well because it intertwines the leftmost and rightmost descend towards leaf edges, doing the two root node accesses close together, perhaps exploiting a CPU's internal pipelining? So the third commit distils a version of `range_search` (which we can't use directly because of the `Ord` bound), and we get another boost:
```
cargo-benchcmp.exe benchcmp a2 a3 --threshold 5
name a2 ns/iter a3 ns/iter diff ns/iter diff % speedup
btree::map::first_and_last_100 40 43 3 7.50% x 0.93
btree::map::first_and_last_10k 71 64 -7 -9.86% x 1.11
btree::map::iter_0 2,209 1,719 -490 -22.18% x 1.29
btree::map::iter_1 2,696 2,205 -491 -18.21% x 1.22
btree::map::iter_100 3,672 2,943 -729 -19.85% x 1.25
btree::map::iter_10k 5,884 3,929 -1,955 -33.23% x 1.50
btree::map::iter_1m 6,510 5,532 -978 -15.02% x 1.18
btree::map::iteration_mut_100000 453,050 476,667 23,617 5.21% x 0.95
btree::map::range_included_excluded 405,075 371,297 -33,778 -8.34% x 1.09
btree::map::range_included_included 427,577 397,440 -30,137 -7.05% x 1.08
btree::map::range_unbounded_unbounded 36,169 28,175 -7,994 -22.10% x 1.28
btree::map::range_unbounded_vs_iter 38,290 30,838 -7,452 -19.46% x 1.24
```
But I think this is just fake news from the microbenchmarking media. `iter()` is still trying to catch up with `range(..)`. And we can sure do without another function. So I would skip this 3rd commit.
r? @Mark-Simulacrum
perf: Unify the undo log of all snapshot types
Extracted from #69218 and extended to all the current snapshot types.
Since snapshotting is such a frequent action in the compiler and many of the scopes execute so little work, the act of creating the snapshot and rolling back empty/small snapshots end up showing in perf. By unifying all the logs into one the creation of snapshots becomes significantly cheaper at the cost of some complexity when combining the log with the specific data structures that are being mutated.
Depends on https://github.com/rust-lang-nursery/ena/pull/29
Update RLS
In addition to fixing the toolstate, this also changes the default
compilation model to the out-of-process one, which should hopefully
target considerable memory usage for long-running instances of the RLS.
Fixes#71753
r? @ghost
We don't want to export any symbols from Rust's version of libunwind
as these may collide with other copies of libunwind e.g. when linking
Rust staticlib together C/C++ libraries that have their own version.
In addition to fixing the toolstate, this also changes the default
compilation model to the out-of-process one, which should hopefully
target considerable memory usage for long-running instances of the RLS.
Rollup of 4 pull requests
Successful merges:
- #69984 (Add Option to Force Unwind Tables)
- #71830 (Remove clippy from some leftover lists of "possibly failing" tools)
- #71894 (Suggest removing semicolon in last expression only if it's type is known)
- #71897 (Improve docs for embed-bitcode and linker-plugin-lto)
Failed merges:
r? @ghost
Suggest removing semicolon in last expression only if it's type is known
Fixes#67971
Is there a syntax for explicitly checking if a note doesn't exist in test output? Something like `//~ !NOTE ...`
I believe r? @estebank deals with diagnostics.
Remove clippy from some leftover lists of "possibly failing" tools
https://github.com/rust-lang/rust/pull/70655 successfully made clippy get built and tested on CI on every merge, but the lack of emitted toolstate info caused the toolstate to get updated to test-fail. We should remove clippy entirely from toolstate, as it now is always test-pass.
The changes made in this PR reflect what we do for `rustdoc`, which is our preexisting tool that is gated on CI.
r? @Mark-Simulacrum
Add Option to Force Unwind Tables
When panic != unwind, `nounwind` is added to all functions for a target.
This can cause issues when a panic happens with RUST_BACKTRACE=1, as
there needs to be a way to reconstruct the backtrace. There are three
possible sources of this information: forcing frame pointers (for which
an option exists already), debug info (for which an option exists), or
unwind tables.
Especially for embedded devices, forcing frame pointers can have code
size overheads (RISC-V sees ~10% overheads, ARM sees ~2-3% overheads).
In production code, it can be the case that debug info is not kept, so it is useful
to provide this third option, unwind tables, that users can use to
reconstruct the call stack. Reconstructing this stack is harder than
with frame pointers, but it is still possible.
---
This came up in discussion on #69890, and turned out to be a fairly simple addition.
r? @hanna-kruppe
