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Change vtable memory representation to use tcx allocated allocations. #86475

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merged 3 commits into from
Jun 29, 2021
Merged

Change vtable memory representation to use tcx allocated allocations. #86475

merged 3 commits into from
Jun 29, 2021

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crlf0710
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This fixes #86324. However i suspect there's more to change before it can land.

r? @bjorn3
cc @rust-lang/miri

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Some changes occured to the CTFE / Miri engine

cc @rust-lang/miri

Some changes occured to the CTFE / Miri engine

cc @rust-lang/miri

@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jun 19, 2021
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RalfJung commented Jun 20, 2021 •
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I am very confused by the PR title. Surely Miri should still use its own allocations for stack and heap allocations. Also the change seems to have a lot to do with vtables, but that term does not appear in the PR title. It would help to describe more precisely what is going on. :)

EDIT: Oh, looks like what you mean use "Change Miri to use txc-allocation allocation for vtables". That makes a lot more sense. You had me worried at first here. ;)
That's not the whole change though, is it? It also removes vtable generation from other parts of the compiler.

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bjorn3 commented Jun 20, 2021

If you don't know yet ./x.py check should check cg_clif by default unlike ./x.py build. You can make ./x.py build also build cg_clif by adding "cranelift" to the rust.codegen-backends array in config.toml.

@crlf0710 crlf0710 changed the title Change miri to use tcx allocated allocations. Change vtable memory representation to use tcx allocated allocations. Jun 20, 2021
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Thank you for your comments! I'll update the pr and address the review comments tomorrow evening in my timezone (after about 18 hours)

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oli-obk commented Jun 21, 2021

Thank you for your comments! I'll update the pr and address the review comments tomorrow evening in my timezone (after about 18 hours)

No rush. Take all the time you need. There's no expectation that reviews are addressed in any timeframe other than what the author feels good with.

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Thanks! I was a little busy this week, i'll get to it this weekend.

@crlf0710 crlf0710 force-pushed the miri_vtable_refactor branch 2 times, most recently from 10b692c to c1eafa7 Compare June 27, 2021 11:38
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Updated and addressed the comments.

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bjorn3 commented Jun 28, 2021

Only x86_64-apple timed out. All other jobs succeeded. Probably spurious.

@bors retry

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 28, 2021
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A job failed! Check out the build log: (web) (plain)

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bors commented Jun 29, 2021

⌛ Testing commit 97772bb with merge 12d658d005db54ae0594fa815a70d2ab79747b70...

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bors commented Jun 29, 2021

💔 Test failed - checks-actions

@bors bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jun 29, 2021
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A job failed! Check out the build log: (web) (plain)

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2021-06-29T10:40:18.9223083Z curl: (56) OpenSSL SSL_read: Connection was reset, errno 10054
2021-06-29T10:40:18.9316146Z ##[error]Process completed with exit code 56.

Mmm, it seems another retry is needed? Or do i need to rebase forward? @bjorn3

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bjorn3 commented Jun 29, 2021

@bors retry

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 29, 2021
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bors commented Jun 29, 2021

⌛ Testing commit 97772bb with merge e98897e...

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bors commented Jun 29, 2021

☀️ Test successful - checks-actions
Approved by: bjorn3
Pushing e98897e to master...

@bors bors added the merged-by-bors This PR was explicitly merged by bors. label Jun 29, 2021
@bors bors merged commit e98897e into rust-lang:master Jun 29, 2021
@rustbot rustbot added this to the 1.55.0 milestone Jun 29, 2021
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📣 Toolstate changed by #86475!

Tested on commit e98897e.
Direct link to PR: #86475

💔 miri on windows: test-pass → build-fail (cc @eddyb @oli-obk @RalfJung).
💔 miri on linux: test-pass → build-fail (cc @eddyb @oli-obk @RalfJung).

rust-highfive added a commit to rust-lang-nursery/rust-toolstate that referenced this pull request Jun 29, 2021
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📣 Toolstate changed by rust-lang/rust#86475!
6c9ff64 
Tested on commit rust-lang/rust@e98897e.
Direct link to PR: <rust-lang/rust#86475>

💔 miri on windows: test-pass → build-fail (cc @eddyb @oli-obk @RalfJung).
💔 miri on linux: test-pass → build-fail (cc @eddyb @oli-obk @RalfJung).
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bjorn3 commented Jun 29, 2021

Third time's the charm.

@bors bors mentioned this pull request Jun 29, 2021
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@crlf0710 crlf0710 deleted the miri_vtable_refactor branch June 30, 2021 04:03
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bjorn3 pushed a commit to bjorn3/rust that referenced this pull request Jul 7, 2021
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Auto merge of rust-lang#86475 - crlf0710:miri_vtable_refactor, r=bjorn3
b186f86 
Change vtable memory representation to use tcx allocated allocations.

This fixes rust-lang#86324. However i suspect there's more to change before it can land.

r? `@bjorn3`
cc `@rust-lang/miri`
eddyb
eddyb reviewed Aug 2, 2021
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compiler/rustc_middle/src/ty/context.rs
Comment on lines +1048 to +1050

pub(super) vtables_cache:
Lock<FxHashMap<(Ty<'tcx>, Option<ty::PolyExistentialTraitRef<'tcx>>), AllocId>>,
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Hmm, any reason this is a mutable cache in the global context, instead of a query? It looks like the kind of thing we replaced with queries long ago.

(Maybe we should find a way to ban !Freeze types in GlobalCtxt, outside of incremental/query state?)

cc @oli-obk @wesleywiser

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I actually gave it a try as a query locally, but without succeed. The compilation complained about keys becoming bigger, something like that, i can't remember the exact error content.

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Ah, that's because that key type is a bit too "spread out". Sadly you can't just use TraitRef<'tcx>, without passing some dummy trait for the DefId.

You could "just" update the expected size, but someone would need to check off on that (and I don't know who) - the problem there is it can affect performance even if the new query is completely unused.

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Having a cache without any dependency tracking looks like a bug to me.

eddyb
eddyb reviewed Aug 2, 2021
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compiler/rustc_codegen_ssa/src/traits/consts.rs
@@ -26,6 +26,8 @@ pub trait ConstMethods<'tcx>: BackendTypes {
fn const_to_opt_uint(&self, v: Self::Value) -> Option<u64>;
fn const_to_opt_u128(&self, v: Self::Value, sign_ext: bool) -> Option<u128>;

fn const_data_from_alloc(&self, alloc: &Allocation) -> Self::Value;
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This is just from_const_alloc, isn't it? Just with a hardcoded offset of 0 and no type.

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from_const_alloc also returns a PlaceRef while this returns a raw pointer value.

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Right, but the PlaceRef is made from that pointer value and the type/layout passed in.

@michaelwoerister michaelwoerister mentioned this pull request Oct 6, 2021
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Refactor: have miri create an Allocation for the vtable
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