Add 0..=isize::MAX range metadata to size loads from vtables by erikdesjardins ·...
source link: https://github.com/rust-lang/rust/pull/105446
Go to the source link to view the article. You can view the picture content, updated content and better typesetting reading experience. If the link is broken, please click the button below to view the snapshot at that time.
Add 0..=isize::MAX range metadata to size loads from vtables #105446
Conversation
Contributor
erikdesjardins
commented
Dec 8, 2022
This is the (much belated) size counterpart to #91569.
Inspired by https://rust-lang.zulipchat.com/#narrow/stream/187780-t-compiler.2Fwg-llvm/topic/Range.20metadata.20for.20.60size_of_val.60.20and.20other.20isize.3A.3AMAX.20limits. This could help optimize layout computations based on the size of a dyn trait. Though, admittedly, adding this to vtables wouldn't be as beneficial as adding it to slice len, which is used much more often.
Miri detects this UB already:
(In fact Miri goes further, assuming a 48-bit address space on 64-bit platforms, but I don't think we can assume that in an optimization.)Collaborator
rustbot commented Dec 8, 2022
|
(rustbot has picked a reviewer for you, use r? to override) |
added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.
labels
Contributor
nikic commented Dec 8, 2022
This comment has been minimized.
added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label
Contributor
bors commented Dec 8, 2022
Trying commit Contributor
bors commented Dec 8, 2022
|
|
Try build successful - This comment has been minimized.
Collaborator
rust-timer commented Dec 8, 2022
|
Finished benchmarking commit (1e9be93): comparison URL. Overall result: no relevant changes - no action neededBenchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf. @bors rollup=never Instruction countThis benchmark run did not return any relevant results for this metric. Max RSS (memory usage)Results CyclesResults |
removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label
Contributor
petrochenkov commented Dec 18, 2022
|
r? @nikic |
Contributor
nikic commented Dec 18, 2022
|
@bors r+ |
Contributor
bors commented Dec 18, 2022
Commit added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion.
and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties.
labels
Contributor
bors commented Dec 18, 2022
Contributor
bors commented Dec 19, 2022
|
|
Collaborator
rust-timer commented Dec 19, 2022
|
Finished benchmarking commit (2b094b1): comparison URL. Overall result:
|
| mean | range | count | |
|---|---|---|---|
Regressions  (primary) |
- | - | 0 |
| Regressions (secondary) |
- | - | 0 |
Improvements  (primary) |
- | - | 0 |
| Improvements (secondary) |
-1.1% | [-1.1%, -1.1%] | 1 |
| All (primary) |
- | - | 0 |
Max RSS (memory usage)
Results
Cycles
This benchmark run did not return any relevant results for this metric.
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
None yet
Successfully merging this pull request may close these issues.
None yet
Recommend
About Joyk
Aggregate valuable and interesting links.
Joyk means Joy of geeK