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Merged
merged 1 commit into from
Jan 26, 2018
Merged

[4.1][sil] When expanding aggregate instructions, do so consistently based… #14163

merged 1 commit into from
Jan 26, 2018

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gottesmm
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… off the code-size hueristic.

We were expanding retain_value, release_value properly, but not
copy_addr/destroy_addr. This caused ARC invariants to break resulting in
miscompiles.

rdar://36509461

@gottesmm gottesmm force-pushed the swift-4.1-branch_rdar36509461 branch from a4e30df to 6ca0f7a Compare January 25, 2018 19:20
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@swift-ci test

@gottesmm gottesmm requested a review from shajrawi January 25, 2018 20:01
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shajrawi suggested changes Jan 25, 2018
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include/swift/SIL/TypeLowering.h: static TypeExpansionKind getLoweringStyle(bool shouldExpand) { is no longer used after this change, can you please remove said function? Otherwise LGTM!

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Explanation: This commit ensures that when we canonicalize aggregate ARC operations on large structs, we do so consistently no matter the ARC operation that is used.
Scope: This is an important change since the inconsistent canonicalization can result in the ARC optimizer miscompiling. Additionally, this most likely caused us to lose code-size.
Radar (and possibly SR Issue): rdar://36509461
Risk: There is low risk to this change since we are just returning to our original consistency and the actual change in codegen is small. The risk to not taking this commit is high due to the possibility of ARC miscompiles.
Testing: I wrote compiler tests that validate that we are consistently expanded (or not) aggregate ARC operations.

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@shajrawi, @eeckstein asked me to make this as small as possible. I would rather just leave it in.

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Actually, I am going to come up with a test for the actual ARC failure as well for this PR. So I guess I can go through another test cycle.

@gottesmm
[sil] When expanding aggregate instructions, do so consistently based…
c52011a 
… off the code-size hueristic.

We were expanding retain_value, release_value properly, but not
copy_addr/destroy_addr. This caused ARC invariants to break resulting in
miscompiles.

rdar://36509461
@gottesmm gottesmm force-pushed the swift-4.1-branch_rdar36509461 branch from 6ca0f7a to c52011a Compare January 25, 2018 21:56
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@swift-ci test

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@swift-ci test

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@swift-ci test

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@swift-ci test

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@swift-ci test

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@swift-ci test

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@shahmishal Is something wrong here? Or am I being impatient?

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nm. The bots are being upgraded.

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Build failed
Swift Test OS X Platform
Git Sha - 6ca0f7ac821ca2ac446bdfebdd509ad5a82d0741

@gottesmm gottesmm changed the title [sil] When expanding aggregate instructions, do so consistently based… [4.1][sil] When expanding aggregate instructions, do so consistently based… Jan 26, 2018
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@swift-ci test

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@swift-ci test

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@swift-ci test

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@swift-ci test

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@swift-ci test

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Please wait for CI to catch up.

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Build failed
Swift Test Linux Platform
Git Sha - 6ca0f7ac821ca2ac446bdfebdd509ad5a82d0741

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Build failed
Swift Test OS X Platform
Git Sha - 6ca0f7ac821ca2ac446bdfebdd509ad5a82d0741

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Sorry for being so impatient Mishal!

@gottesmm gottesmm merged commit 5065593 into swiftlang:swift-4.1-branch Jan 26, 2018
@gottesmm gottesmm deleted the swift-4.1-branch_rdar36509461 branch January 26, 2018 19:35
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