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read_via_copy: don't prematurely optimize away the read #115531

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Merged
merged 1 commit into from
Sep 5, 2023
Merged

read_via_copy: don't prematurely optimize away the read #115531

merged 1 commit into from
Sep 5, 2023
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RalfJung
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@RalfJung RalfJung commented Sep 4, 2023

Always do the read to ensure consistent UB error messages in const-eval/Miri.

r? @scottmcm

@rustbot rustbot 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 Sep 4, 2023
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rustbot commented Sep 4, 2023

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

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RalfJung commented Sep 4, 2023

Something is broken with CI, everything fails with Error: Can't use 'tar -xzf' extract archive file: /home/runner/work/_actions/_temp_9df9ab2c-c8c6-4350-906b-1888c557ad16/584cf8e8-7843-48e0-9221-d6f46700efee.tar.gz. return code: 2..
@bors treeclosed=100

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@RalfJung RalfJung reopened this Sep 4, 2023
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scottmcm
scottmcm reviewed Sep 4, 2023
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tests/ui/consts/const-eval/ub-uninhabit.rs

const BAD_BAD_ARRAY: [Bar; 1] = unsafe { MaybeUninit { uninit: () }.init };
//~^ ERROR evaluation of constant value failed
//~| constructing invalid value


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hyper-nit: extra blank lines in here

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scottmcm commented Sep 4, 2023

FYI @WaffleLapkin, who sortof-suggested removing the assignment in #109035 (comment)

But this PR is a good answer for why it shouldn't be removed, so the change LGTM.

@bors r+

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bors commented Sep 4, 2023

📌 Commit 7093903 has been approved by scottmcm

It is now in the queue for this repository.

@bors bors 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 Sep 4, 2023
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bors commented Sep 4, 2023

⌛ Testing commit 7093903 with merge ac542f7fbb011f3811c032e3b3faa0642161a126...

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bors commented Sep 4, 2023

💔 Test failed - checks-actions

@bors bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Sep 4, 2023
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ehuss commented Sep 4, 2023

@bors retry

GitHub checkout failed

@bors bors 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 Sep 4, 2023
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A job failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot) 
Prepare workflow directory
Prepare all required actions
Getting action download info
Download action repository 'actions/checkout@v3' (SHA:f43a0e5ff2bd294095638e18286ca9a3d1956744)
##[error]Can't use 'tar -xzf' extract archive file: /home/runner/work/_actions/_temp_ac181360-3d12-41f2-ada0-882bd3bf1425/81eb450d-8849-429c-b079-ddc42e08edbe.tar.gz. return code: 2.

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bors commented Sep 5, 2023

⌛ Testing commit 7093903 with merge c505b8b95e28731a9e5fac10c2dd2c959e6b80d3...

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A job failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot) 
Prepare workflow directory
Prepare all required actions
Getting action download info
Download action repository 'actions/checkout@v3' (SHA:f43a0e5ff2bd294095638e18286ca9a3d1956744)
##[error]Can't use 'tar -xzf' extract archive file: /home/runner/work/_actions/_temp_9ee4439e-16af-43a6-bebb-8597a7a8a9b7/d0aadeff-c388-45be-8505-7094c7881131.tar.gz. return code: 2.

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bors commented Sep 5, 2023

💔 Test failed - checks-actions

@bors bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Sep 5, 2023
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ehuss commented Sep 5, 2023

@bors retry

GitHub checkout issue

@bors bors 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 Sep 5, 2023
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bors commented Sep 5, 2023

⌛ Testing commit 7093903 with merge 626a6ab...

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bors commented Sep 5, 2023

☀️ Test successful - checks-actions
Approved by: scottmcm
Pushing 626a6ab to master...

@bors bors added the merged-by-bors This PR was explicitly merged by bors. label Sep 5, 2023
@bors bors merged commit 626a6ab into rust-lang:master Sep 5, 2023
@rustbot rustbot added this to the 1.74.0 milestone Sep 5, 2023
@RalfJung RalfJung deleted the read_via_copy branch September 5, 2023 06:13
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Finished benchmarking commit (626a6ab): comparison URL.

Overall result: ✅ improvements - no action needed

@rustbot label: -perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

mean range count
Regressions ❌
(primary)		 - - 0
Regressions ❌
(secondary)		 - - 0
Improvements ✅
(primary)		 -0.7% [-0.7%, -0.7%] 5
Improvements ✅
(secondary)		 - - 0
All ❌✅ (primary) -0.7% [-0.7%, -0.7%] 5

Max RSS (memory usage)

This benchmark run did not return any relevant results for this metric.

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

mean range count
Regressions ❌
(primary)		 1.1% [0.8%, 1.3%] 2
Regressions ❌
(secondary)		 - - 0
Improvements ✅
(primary)		 - - 0
Improvements ✅
(secondary)		 -2.3% [-2.3%, -2.3%] 1
All ❌✅ (primary) 1.1% [0.8%, 1.3%] 2

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 628.296s -> 627.535s (-0.12%)
Artifact size: 316.10 MiB -> 316.30 MiB (0.06%)

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FYI @WaffleLapkin, who sortof-suggested removing the assignment in #109035 (comment)

Oops 😅

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