Refactor object file handling #70384
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It's unused by any existing targets, and soon we'll be embedding full bitcode by default anyway.
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In theory this shouldn't affect performance at all, but let's check that: @bors try @rust-timer queue |
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Awaiting bors try build completion |
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⌛ Trying commit 72f1c6cfed177a356c7e05d16ba778cb1cb45078 with merge 8753044243364ce6751612dea9eae4439dcad8ce... |
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If I remember correctly "marker" bitcode embedding had something to do with iOS compatibility? #35968 has some discussion on it; but @alexcrichton would know more about that anyway. |
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☀️ Try build successful - checks-azure |
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Queued 8753044243364ce6751612dea9eae4439dcad8ce with parent cdb50c6, future comparison URL. |
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The perf impact is negligible, as expected. |
Currently, there are three fields in `ModuleConfig` that dictate how object files are emitted: `emit_obj`, `obj_is_bitcode`, and `embed_bitcode`. Some of the combinations of these fields are nonsensical, in particular having both `obj_is_bitcode` and `embed_bitcode` true at the same time. Also, currently: - we needlessly emit and then delete a bytecode file if `obj_is_bitcode` is true but `emit_obj` is false; - we needlessly embed bitcode in the LLVM module if `embed_bitcode` is true and `emit_obj` is false. This commit combines the three fields into one, with a new type `EmitObj` (and the auxiliary `BitcodeSection`) which can encode five different possibilities. In the old code, `set_flags` would set `obj_is_bitcode` and `embed_bitcode` on all three of the configs (`modules`, `allocator`, `metadata`) if the relevant other conditions were met, even if no object code needed to be emitted for one or more of them. Whereas `start_async_codegen` would set `emit_obj`, but only for those configs that need it. In the new code, `start_async_codegen` does all the work of setting `emit_obj`, and it only does that for the configs that need it. `set_flags` no longer sets anything related to object file emission.
It makes things a little clearer.
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@alexcrichton New code is up. I reinstated marker bitcode sections (in a nicer fashion than we had before) and did other minor changes you suggested where possible. |
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@bors: r+ |
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📌 Commit a50cca9 has been approved by |
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…ndling, r=alexcrichton Refactor object file handling Some preliminary clean-ups that grease the path to rust-lang#66961. r? @alexcrichton
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Rollup of 6 pull requests Successful merges: - rust-lang#70384 (Refactor object file handling) - rust-lang#70397 (add 'fn write_u16s' to Memory) - rust-lang#70413 (Fix incorrect pattern warning "unreachable pattern") - rust-lang#70428 (`error_bad_item_kind`: add help text) - rust-lang#70429 (Clean up E0459 explanation) - rust-lang#70437 (Miri float->int casts: be explicit that this is saturating) Failed merges: r? @ghost
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Some preliminary clean-ups that grease the path to #66961.
r? @alexcrichton