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Reduce maximum repr(align(N)) to 2^29 #50378

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May 3, 2018
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@varkor varkor commented May 1, 2018

The current maximum repr(align(N)) alignment is larger than the maximum alignment accepted by LLVM, which can cause issues for huge values of N, as seen in #49492. Fixes #49492.

r? @rkruppe

@varkor varkor changed the title Repr align max 29 Reduce maximum repr(align(N)) to 2^29 May 1, 2018
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varkor commented May 1, 2018

r? @rkruppe (I think something's wrong with @rust-highfive :( )

/// with a maximum capacity of 2<sup>31</sup> - 1 or 2147483647.
/// Each field is a power of two, giving the alignment a maximum value
/// of 2<sup>(2<sup>8</sup> - 1)</sup>, which is limited by LLVM to a
/// maximum capacity of 2<sup>29</sup> or 536870912.
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I'm pretty sure Align::from_bytes needs to be updated to reflect this.

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Ah, of course!

@kennytm kennytm added T-lang Relevant to the language team, which will review and decide on the PR/issue. S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels May 1, 2018
varkor added 2 commits May 1, 2018 22:01
This brings it into line with LLVM's maximum permitted alignment.
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cc @eddyb

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eddyb commented May 1, 2018

@bors r+

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bors commented May 1, 2018

📌 Commit cd2f5f7 has been approved by eddyb

@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 May 1, 2018
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bors commented May 3, 2018

⌛ Testing commit cd2f5f7 with merge 427c548...

bors added a commit that referenced this pull request May 3, 2018
Reduce maximum repr(align(N)) to 2^29

The current maximum `repr(align(N))` alignment is larger than the maximum alignment accepted by LLVM, which can cause issues for huge values of `N`, as seen in #49492. Fixes #49492.

r? @rkruppe
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bors commented May 3, 2018

☀️ Test successful - status-appveyor, status-travis
Approved by: eddyb
Pushing 427c548 to master...

@bors bors merged commit cd2f5f7 into rust-lang:master May 3, 2018
@varkor varkor deleted the repr-align-max-29 branch May 3, 2018 09:24
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5 participants