rustc: Implement incremental "fat" LTO #58378
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r? @zackmdavis (rust_highfive has picked a reviewer for you, use r? to override) |
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☔ The latest upstream changes (presumably #58389) made this pull request unmergeable. Please resolve the merge conflicts. |
Currently the compiler will produce an error if both incremental compilation and full fat LTO is requested. With recent changes and the advent of incremental ThinLTO, however, all the hard work is already done for us and it's actually not too bad to remove this error! This commit updates the codegen backend to allow incremental full fat LTO. The semantics are that the input modules to LTO are all produce incrementally, but the final LTO step is always done unconditionally regardless of whether the inputs changed or not. The only real incremental win we could have here is if zero of the input modules changed, but that's so rare it's unlikely to be worthwhile to implement such a code path. cc rust-lang#57968 cc rust-lang/cargo#6643
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I skimmed through this, looks good! I'll be able to do a proper review tomorrow hopefully. |
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Thanks, @alexcrichton! Looks great! But wow has this code become complicated. I think the whole backend is up for a re-write once a thread-safe tcx is in place... @bors r+ |
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…haelwoerister rustc: Implement incremental "fat" LTO Currently the compiler will produce an error if both incremental compilation and full fat LTO is requested. With recent changes and the advent of incremental ThinLTO, however, all the hard work is already done for us and it's actually not too bad to remove this error! This commit updates the codegen backend to allow incremental full fat LTO. The semantics are that the input modules to LTO are all produce incrementally, but the final LTO step is always done unconditionally regardless of whether the inputs changed or not. The only real incremental win we could have here is if zero of the input modules changed, but that's so rare it's unlikely to be worthwhile to implement such a code path. cc rust-lang#57968 cc rust-lang/cargo#6643
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Rollup of 7 pull requests Successful merges: - #58309 (Add more profiler events) - #58347 (Closure bounds fixes) - #58365 (Add an option to print the status of incremental tasks / dep nodes after running them) - #58371 (Check user type annotations for range patterns.) - #58378 (rustc: Implement incremental "fat" LTO) - #58407 (specify "upper camel case" in style lint) - #58449 (Notify @topecongiro when the state of rustfmt has changed) Failed merges: r? @ghost
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Currently the compiler will produce an error if both incremental
compilation and full fat LTO is requested. With recent changes and the
advent of incremental ThinLTO, however, all the hard work is already
done for us and it's actually not too bad to remove this error!
This commit updates the codegen backend to allow incremental full fat
LTO. The semantics are that the input modules to LTO are all produce
incrementally, but the final LTO step is always done unconditionally
regardless of whether the inputs changed or not. The only real
incremental win we could have here is if zero of the input modules
changed, but that's so rare it's unlikely to be worthwhile to implement
such a code path.
cc #57968
cc rust-lang/cargo#6643