make retagging work even with 'unstable' places #105317
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Some changes occurred to the CTFE / Miri engine cc @rust-lang/miri The Miri subtree was changed cc @rust-lang/miri Some changes occurred to MIR optimizations cc @rust-lang/wg-mir-opt This PR changes MIR cc @oli-obk, @RalfJung, @JakobDegen, @davidtwco, @celinval, @vakaras |
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@bors r+ |
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📌 Commit 1b43d0083976a21cd31a5000ff346b564f232055 has been approved by It is now in the queue for this repository. |
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…retag into a separate function
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matthiaskrgr
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make retagging work even with 'unstable' places This is based on top of rust-lang#105301. Only the last two commits are new. While investigating rust-lang/unsafe-code-guidelines#381 I realized that we would have caught this issue much earlier if the add_retag pass wouldn't bail out on assignments of the form `*ptr = ...`. So this PR changes our retag strategy: - When a new reference is created via `Rvalue::Ref` (or a raw ptr via `Rvalue::AddressOf`), we do the retagging as part of just executing that address-taking operation. - For everything else, we still insert retags -- these retags basically serve to ensure that references stored in local variables (and their fields) are always freshly tagged, so skipping this for assignments like `*ptr = ...` is less egregious. r? `@oli-obk`
matthiaskrgr
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Dec 8, 2022
make retagging work even with 'unstable' places This is based on top of rust-lang#105301. Only the last two commits are new. While investigating rust-lang/unsafe-code-guidelines#381 I realized that we would have caught this issue much earlier if the add_retag pass wouldn't bail out on assignments of the form `*ptr = ...`. So this PR changes our retag strategy: - When a new reference is created via `Rvalue::Ref` (or a raw ptr via `Rvalue::AddressOf`), we do the retagging as part of just executing that address-taking operation. - For everything else, we still insert retags -- these retags basically serve to ensure that references stored in local variables (and their fields) are always freshly tagged, so skipping this for assignments like `*ptr = ...` is less egregious. r? ``@oli-obk``
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Dec 9, 2022
…iaskrgr Rollup of 10 pull requests Successful merges: - rust-lang#104922 (Detect long types in E0308 and write them to disk) - rust-lang#105120 (kmc-solid: `std::sys` code maintenance) - rust-lang#105255 (Make nested RPIT inherit the parent opaque's generics.) - rust-lang#105317 (make retagging work even with 'unstable' places) - rust-lang#105405 (Stop passing -export-dynamic to wasm-ld.) - rust-lang#105408 (Add help for `#![feature(impl_trait_in_fn_trait_return)]`) - rust-lang#105423 (Use `Symbol` for the crate name instead of `String`/`str`) - rust-lang#105433 (CI: add missing line continuation marker) - rust-lang#105434 (Fix warning when libcore is compiled with no_fp_fmt_parse) - rust-lang#105441 (Remove `UnsafetyState`) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
Aaron1011
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make retagging work even with 'unstable' places This is based on top of rust-lang#105301. Only the last two commits are new. While investigating rust-lang/unsafe-code-guidelines#381 I realized that we would have caught this issue much earlier if the add_retag pass wouldn't bail out on assignments of the form `*ptr = ...`. So this PR changes our retag strategy: - When a new reference is created via `Rvalue::Ref` (or a raw ptr via `Rvalue::AddressOf`), we do the retagging as part of just executing that address-taking operation. - For everything else, we still insert retags -- these retags basically serve to ensure that references stored in local variables (and their fields) are always freshly tagged, so skipping this for assignments like `*ptr = ...` is less egregious. r? ```@oli-obk```
Aaron1011
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…iaskrgr Rollup of 10 pull requests Successful merges: - rust-lang#104922 (Detect long types in E0308 and write them to disk) - rust-lang#105120 (kmc-solid: `std::sys` code maintenance) - rust-lang#105255 (Make nested RPIT inherit the parent opaque's generics.) - rust-lang#105317 (make retagging work even with 'unstable' places) - rust-lang#105405 (Stop passing -export-dynamic to wasm-ld.) - rust-lang#105408 (Add help for `#![feature(impl_trait_in_fn_trait_return)]`) - rust-lang#105423 (Use `Symbol` for the crate name instead of `String`/`str`) - rust-lang#105433 (CI: add missing line continuation marker) - rust-lang#105434 (Fix warning when libcore is compiled with no_fp_fmt_parse) - rust-lang#105441 (Remove `UnsafetyState`) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
matthiaskrgr
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Mar 21, 2023
not *all* retags might be explicit in Runtime MIR In rust-lang#105317 I made Miri treat `Rvalue::Ref/AddrOf` as implicit retagging sites. This updates the MIR docs accordingly. For `Rvalue::Ref` I think this makes a lot more sense: creating a new reference is their entire point, so we can avoid bloating the MIR with retags. Also this seems to be the best way to handle cases like `*ptr = &[mut] ...`, where doing a retag is somewhat questionable since maybe `*ptr` points to another place now? For `Rvalue::AddrOf`, Stacked Borrows needs this because even raw ptrs need some retagging, but Tree Borrows doesn't do ant retagging here and I hope we'll end up with a model where raw pointers don't get retagged.
matthiaskrgr
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Mar 21, 2023
not *all* retags might be explicit in Runtime MIR In rust-lang#105317 I made Miri treat `Rvalue::Ref/AddrOf` as implicit retagging sites. This updates the MIR docs accordingly. For `Rvalue::Ref` I think this makes a lot more sense: creating a new reference is their entire point, so we can avoid bloating the MIR with retags. Also this seems to be the best way to handle cases like `*ptr = &[mut] ...`, where doing a retag is somewhat questionable since maybe `*ptr` points to another place now? For `Rvalue::AddrOf`, Stacked Borrows needs this because even raw ptrs need some retagging, but Tree Borrows doesn't do ant retagging here and I hope we'll end up with a model where raw pointers don't get retagged.
Nilstrieb
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Mar 21, 2023
not *all* retags might be explicit in Runtime MIR In rust-lang#105317 I made Miri treat `Rvalue::Ref/AddrOf` as implicit retagging sites. This updates the MIR docs accordingly. For `Rvalue::Ref` I think this makes a lot more sense: creating a new reference is their entire point, so we can avoid bloating the MIR with retags. Also this seems to be the best way to handle cases like `*ptr = &[mut] ...`, where doing a retag is somewhat questionable since maybe `*ptr` points to another place now? For `Rvalue::AddrOf`, Stacked Borrows needs this because even raw ptrs need some retagging, but Tree Borrows doesn't do ant retagging here and I hope we'll end up with a model where raw pointers don't get retagged.
Nilstrieb
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Mar 21, 2023
not *all* retags might be explicit in Runtime MIR In rust-lang#105317 I made Miri treat `Rvalue::Ref/AddrOf` as implicit retagging sites. This updates the MIR docs accordingly. For `Rvalue::Ref` I think this makes a lot more sense: creating a new reference is their entire point, so we can avoid bloating the MIR with retags. Also this seems to be the best way to handle cases like `*ptr = &[mut] ...`, where doing a retag is somewhat questionable since maybe `*ptr` points to another place now? For `Rvalue::AddrOf`, Stacked Borrows needs this because even raw ptrs need some retagging, but Tree Borrows doesn't do ant retagging here and I hope we'll end up with a model where raw pointers don't get retagged.
Nilstrieb
added a commit
to Nilstrieb/rust
that referenced
this pull request
Mar 21, 2023
not *all* retags might be explicit in Runtime MIR In rust-lang#105317 I made Miri treat `Rvalue::Ref/AddrOf` as implicit retagging sites. This updates the MIR docs accordingly. For `Rvalue::Ref` I think this makes a lot more sense: creating a new reference is their entire point, so we can avoid bloating the MIR with retags. Also this seems to be the best way to handle cases like `*ptr = &[mut] ...`, where doing a retag is somewhat questionable since maybe `*ptr` points to another place now? For `Rvalue::AddrOf`, Stacked Borrows needs this because even raw ptrs need some retagging, but Tree Borrows doesn't do ant retagging here and I hope we'll end up with a model where raw pointers don't get retagged.
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This is based on top of #105301. Only the last two commits are new.
While investigating rust-lang/unsafe-code-guidelines#381 I realized that we would have caught this issue much earlier if the add_retag pass wouldn't bail out on assignments of the form
*ptr = ....So this PR changes our retag strategy:
Rvalue::Ref(or a raw ptr viaRvalue::AddressOf), we do the retagging as part of just executing that address-taking operation.*ptr = ...is less egregious.r? @oli-obk