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SILGen: avoid double copies with 'copy' expr #81861

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Merged
merged 1 commit into from
May 30, 2025
Merged

SILGen: avoid double copies with 'copy' expr #81861

merged 1 commit into from
May 30, 2025
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kavon
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@kavon kavon commented May 30, 2025

SILGen sometimes emits code like:

%y = copy_value %x
%z = explicit_copy_value %y
// %y is otherwise unused

simply because of a missed specification that the sub-expression of a copy expr does not need to be returned owned / at +1; it can be a borrow / +0, since we're going to explicit-copy the value anyway.

Discovered originally in #81858

@kavon kavon requested a review from jckarter as a code owner May 30, 2025 02:49
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kavon commented May 30, 2025

@swift-ci test

@kavon kavon enabled auto-merge May 30, 2025 02:51
@kavon kavon merged commit ec554da into swiftlang:main May 30, 2025
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@jckarter jckarter Awaiting requested review from jckarter jckarter is a code owner

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