Open
Conversation
As far as I can tell it was introduced to allow fat LTO with -Clinker-plugin-lto. Later a change was made to automatically disable ThinLTO summary generation when -Clinker-plugin-lto -Clto=fat is used, so we can safely remove it.
rustbot
added
A-LLVM
Collaborator
|
r? @cuviper rustbot has assigned @cuviper. Use Why was this reviewer chosen?The reviewer was selected based on:
|
bjorn3
commented
Feb 12, 2026
|
|
||
| ModulePassManager MPM; | ||
| bool NeedThinLTOBufferPasses = EmitThinLTO; | ||
| bool NeedThinLTOBufferPasses = true; |
Member
Author
There was a problem hiding this comment.
This used to be true when fat LTO is not used, so I ensured all fat LTO phases do NeedThinLTOBufferPasses = false below.
bjorn3
commented
Feb 12, 2026
| MPM.addPass(BitcodeWriterPass(ThinLTODataOS)); | ||
| } | ||
| MPM.addPass(ThinLTOBitcodeWriterPass( | ||
| ThinLTODataOS, EmitThinLTOSummary ? &ThinLinkDataOS : nullptr)); |
Member
Author
There was a problem hiding this comment.
PreLinkNoLTO is never used when fat LTO is enabled.
bjorn3
commented
Feb 12, 2026
| if (EmitThinLTO) { | ||
| // thin lto summaries prevent fat lto, so do not emit them if fat | ||
| // lto is requested. See PR #136840 for background information. | ||
| if (OptStage != LLVMRustOptStage::PreLinkFatLTO) { |
Member
Author
There was a problem hiding this comment.
This doesn't need to check LLVMRustOptStage::FatLTO as ThinLTOBufferRef is NULL in that case.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
As far as I can tell it was introduced in #98162 to allow fat LTO with
-Clinker-plugin-lto. In #136840 a change was made to automatically disable ThinLTO summary generation when-Clinker-plugin-lto -Clto=fatis used, so we can safely remove it.Fixes #152490