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Add option to reduce build times when using ThinLTO and ld64 #41058

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Merged
merged 4 commits into from
Feb 9, 2022
Merged

Add option to reduce build times when using ThinLTO and ld64 #41058

merged 4 commits into from
Feb 9, 2022

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edymtt
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@edymtt edymtt commented Jan 28, 2022

Internal configurations targeting Darwin employ ThinLTO to
improve compiler performance, however using it on all executable
causes build time to increase with no matching benefit.

To reduce build times in such configurations, we allow some
ancillary targets to opt out of LLVM IR optimizations when linking
ThinLTO with ld64 (e.g. tools used for bootstrapping or debugging the
Swift compiler) -- this behaviour is opt in through a new flag
--swift-tools-ld64-lto-codegen-only-for-supporting-targets.

Addresses rdar://76702687

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Add option to reduce build times when using ThinLTO and ld64
baaf886 
Internal configurations targeting Darwin employ ThinLTO to
improve compiler performance, however using it on all executable
causes build time to increase with no matching benefit.

To reduce build times in such configurations, we allow some
ancillary targets to opt out of LLVM IR optimizations when linking
ThinLTO with ld64 (e.g. tools used for bootstrapping or debugging the
Swift compiler) -- this behaviour is opt in through a new flag
`--swift-tools-ld64-lto-codegen-only-for-supporting-targets`.

Addresses rdar://76702687
@edymtt edymtt mentioned this pull request Jan 28, 2022
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edymtt commented Jan 28, 2022

@swift-ci please smoke test

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edymtt commented Jan 28, 2022

preset=buildbot_incremental,tools=RA,stdlib=RD,smoketest=macosx,flto
@swift-ci Please test with preset macOS Platform

compnerd
compnerd reviewed Jan 28, 2022
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edymtt commented Feb 1, 2022

@swift-ci please smoke test

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edymtt commented Feb 1, 2022

preset=buildbot_incremental,tools=RA,stdlib=RD,smoketest=macosx,flto
@swift-ci Please test with preset macOS Platform

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edymtt commented Feb 3, 2022

preset=buildbot_incremental,tools=RA,stdlib=RD,smoketest=macosx,flto
@swift-ci Please test with preset macOS Platform

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edymtt commented Feb 7, 2022

preset=buildbot_incremental,tools=RA,stdlib=RD,smoketest=macosx,flto
@swift-ci Please test with preset macOS Platform

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edymtt commented Feb 7, 2022

@swift-ci please smoke test

compnerd
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If the swift_build_support test actually passes (the string splitting in python is odd), LGTM. Thanks for cleaning this up!

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edymtt commented Feb 7, 2022

@swift-ci please python lint

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edymtt commented Feb 9, 2022

The build for the preset buildbot_incremental,tools=RA,stdlib=RD,smoketest=macosx,flto seems to have issues unrelated to this PR -- Jenkins seems to lose connection to the node while building llvm, probably due to the load caused by building LTO

@edymtt edymtt merged commit f417630 into swiftlang:main Feb 9, 2022
@edymtt edymtt deleted the thinlto-use-codegen-only-in-ld64-for-some-targets branch February 9, 2022 16:32
@edymtt edymtt mentioned this pull request Jan 15, 2024
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@compnerd compnerd compnerd approved these changes

@drexin drexin Awaiting requested review from drexin

@gottesmm gottesmm Awaiting requested review from gottesmm

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