rustc_llvm: Emit module summaries when using -Clto=fat#159029
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PiJoules
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cc @ilovepi |
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This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed. Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers. |
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Currently, module summaries are only emitted with thin lto. If we would link full/fat lto'd rust code against lto'd c++ code built with CFI (or WPD), those passes would fail during the link step because the participating rust modules are missing module summaries. Rust code does not know at compile-time if it would be participating in some special link which may require module summaries, so this PR ensures module summaries are unconditionally emitted for full/fat lto, just like with thin lto. The WriteBitcodeToFile function just invokes the normal BitcodeWriterPass under the hood, but doesn't provide a way to set the argument for emitting module summaries. So this patch just adds the pass directly and sets that argument. Finally, now that we're generating module summaries for `-Clto=fat` without using ThinLTO, we need to update `rustc-metadata` to keep around a temporary directory that contains the `.rmeta` for a little longer before we deserialize it.
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@bjorn3 - I think I did a force push and lost a comment from you. Does the latest version still have the concern you mentioned? |
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I assume they deleted their own comment, but do speak up if that's still relevant. Otherwise, it looks good to me! @bors r+ |
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I don't fully remember what my comment was, but I did indeed delete it when I realized I was thinking wrong. I don't have any objections to this PR. |
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…iper rustc_llvm: Emit module summaries when using -Clto=fat Currently, module summaries are only emitted with thin lto. If we would link full/fat lto'd rust code against lto'd c++ code built with CFI (or WPD), those passes would fail during the link step because the participating rust modules are missing module summaries. Rust code does not know at compile-time if it would be participating in some special link which may require module summaries, so this PR ensures module summaries are unconditionally emitted for full/fat lto, just like with thin lto. The WriteBitcodeToFile function just invokes the normal BitcodeWriterPass under the hood, but doesn't provide a way to set the argument for emitting module summaries. So this patch just adds the pass directly and sets that argument. This is a rebase of @PiJoules's rust-lang#158099, which also should fix up the tests with the gcc tools.
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…iper rustc_llvm: Emit module summaries when using -Clto=fat Currently, module summaries are only emitted with thin lto. If we would link full/fat lto'd rust code against lto'd c++ code built with CFI (or WPD), those passes would fail during the link step because the participating rust modules are missing module summaries. Rust code does not know at compile-time if it would be participating in some special link which may require module summaries, so this PR ensures module summaries are unconditionally emitted for full/fat lto, just like with thin lto. The WriteBitcodeToFile function just invokes the normal BitcodeWriterPass under the hood, but doesn't provide a way to set the argument for emitting module summaries. So this patch just adds the pass directly and sets that argument. This is a rebase of @PiJoules's rust-lang#158099, which also should fix up the tests with the gcc tools.
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This pull request was unapproved. This PR was contained in a rollup (#159803), which was unapproved. |
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Currently, module summaries are only emitted with thin lto. If we would link full/fat lto'd rust code against lto'd c++ code built with CFI (or WPD), those passes would fail during the link step because the participating rust modules are missing module summaries. Rust code does not know at compile-time if it would be participating in some special link which may require module summaries, so this PR ensures module summaries are unconditionally emitted for full/fat lto, just like with thin lto.
The WriteBitcodeToFile function just invokes the normal BitcodeWriterPass under the hood, but doesn't provide a way to set the argument for emitting module summaries. So this patch just adds the pass directly and sets that argument.
This is a rebase of @PiJoules's #158099, which also should fix up the tests with the gcc tools.