Miri: dispatch first on the type by RalfJung · Pull Request #62946 · rust-lang/rust

RalfJung · 2019-07-24T18:40:40Z

Based on the fact that Miri now always has intptrcast available, we can change binops and casts to first check the type of the source operand and then decide based on that what to do, instead of considering the value (pointer vs bits) first.

rust-highfive · 2019-07-24T18:40:44Z

r? @estebank

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RalfJung · 2019-07-24T18:41:18Z

r? @oli-obk @eddyb

RalfJung · 2019-07-24T18:44:05Z

The Miri side of this is at rust-lang/miri#856. I verified that the test suite passes.

oli-obk

Just some nits

RalfJung · 2019-07-24T21:16:26Z

Actually, the PR as-is makes this fail:

constX2:bool = unsafe{42as*consti32 == 43as*consti32};

The reason is that == on pointer types now always errors, whereas previously it worked if both operands had integer value.

I suppose this is something we have to keep working, for backwards compatibility?

RalfJung · 2019-07-24T21:21:07Z

If we do want this, I think the cleanest way would be to move https://github.com/rust-lang/miri/blob/5a9ea5d1b61a860b95916366b17cce8349450332/src/operator.rs#L52-L78 into the engine. It will still fail in CTFE if either input is a pointer because force_bits will fail.

What do you think?

oli-obk · 2019-07-24T21:22:42Z

No, just break it. Pointer comparisons are unstable at the type level for a reason

RalfJung · 2019-07-24T22:36:05Z

@oli-obk I think I took care of your nits. I also had to update some test files and rebase. Please check.

Centril

nits

RalfJung · 2019-07-25T08:37:17Z

Now that's surprising, why does this affect mir-opt...

RalfJung · 2019-07-25T08:48:03Z

Turns out const_prop was doing ptr-to-int casts based on CTFE doing that. With CTFE not doing that any more, const_prop cannot do it any more, either.

Cc @wesleywiser

oli-obk · 2019-07-31T10:40:14Z

@bors r+

bors · 2019-07-31T10:40:16Z

📌 Commit d7b9bbf has been approved by oli-obk

…en dispatching further; call ptr_op machine hook only for pointer types

…ue second

Co-Authored-By: Mazdak Farrokhzad <twingoow@gmail.com>

RalfJung · 2019-08-02T21:34:10Z

Rebased.

@bors r=oli-obk

bors · 2019-08-02T21:34:11Z

📌 Commit b9db95e has been approved by oli-obk

bors · 2019-08-03T08:33:16Z

⌛ Testing commit b9db95e with merge 8e917f4...

Miri: dispatch first on the type Based on the fact that Miri now always has intptrcast available, we can change binops and casts to first check the type of the source operand and then decide based on that what to do, instead of considering the value (pointer vs bits) first.

bors · 2019-08-03T12:15:17Z

☀️ Test successful - checks-azure
Approved by: oli-obk
Pushing 8e917f4 to master...

Adjust for ptr_op changes This is the Miri side of rust-lang/rust#62946.

rust-highfive assigned estebank Jul 24, 2019

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 24, 2019

rust-highfive assigned oli-obk and unassigned estebank Jul 24, 2019

RalfJung mentioned this pull request Jul 24, 2019
Adjust for ptr_op changes rust-lang/miri#856
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oli-obk reviewed Jul 24, 2019
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Comment threadsrc/librustc_mir/interpret/cast.rs Outdated
Comment threadsrc/librustc_mir/interpret/cast.rs Outdated

RalfJung force-pushed the miri_type_dispatch_first branch 2 times, most recently from 54f900f to 3cd4079Compare July 24, 2019 22:38

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Centril reviewed Jul 25, 2019
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Comment threadsrc/librustc_mir/interpret/cast.rs Outdated
Comment threadsrc/librustc_mir/interpret/operator.rs Outdated

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RalfJung mentioned this pull request Jul 26, 2019
(When) Should we do intptrcast (and other opt-in features) per default? rust-lang/miri#785
Closed
8 tasks

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 Jul 31, 2019

oli-obk mentioned this pull request Jul 31, 2019
[tracking issue] raw ptr to usize cast inside constants #51910
Closed

RalfJung mentioned this pull request Jul 31, 2019
Miri: Check that a ptr is aligned and inbounds already when evaluating *#63075
Merged

bors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Aug 2, 2019

RalfJungand others added 13 commits August 2, 2019 22:33

cast: no need to catch errors any more, force_bits should succeed
44a927a

operator: implement binary_op strictly by first checking the type, th…
48b87c6
…en dispatching further; call ptr_op machine hook only for pointer types

turn cast_immediate into its own function
ec1e718

refactor cast_immediate to dispatch on the type first, and on the val…
b318bcf
…ue second

use From to convert scalars to immediates
780e1fc

fix casts from fat pointers
26c55ec

improve error when CTFE does ptr-int-cast; update tests
7885fac

get rid of some remaining type-based dispatching in cast code
144e5e9

add is_any_ptr type test; this also helps pacify tidy
7b30612

trailing full stops
5fa443d
Co-Authored-By: Mazdak Farrokhzad <twingoow@gmail.com>

bless all the things
f06a274

const_prop no longer does ptr-to-int casts
0f97583

fix rebase fallout
b9db95e

RalfJung force-pushed the miri_type_dispatch_first branch from 12a29d9 to b9db95eCompare August 2, 2019 21:14

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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Aug 2, 2019

bors added the merged-by-bors This PR was explicitly merged by bors. label Aug 3, 2019

bors merged commit b9db95e into rust-lang:masterAug 3, 2019

bors added a commit to rust-lang/miri that referenced this pull request Aug 3, 2019
Auto merge of#856- RalfJung:type_dispatch_first, r=RalfJung
86ffa5d
Adjust for ptr_op changes This is the Miri side of rust-lang/rust#62946.

bors added a commit to rust-lang/miri that referenced this pull request Aug 3, 2019
Auto merge of#856- RalfJung:type_dispatch_first, r=RalfJung
9d3fdee
Adjust for ptr_op changes This is the Miri side of rust-lang/rust#62946.

RalfJung deleted the miri_type_dispatch_first branch August 5, 2019 16:27

chrissimpkins mentioned this pull request Feb 10, 2020
ICE with type_alias_impl_trait: errors selecting obligation during MIR typeck #63355
Closed

matthiaskrgr mentioned this pull request Dec 25, 2023
ICE: ForeignItem(ForeignItem ... is not a valid scope for an opaque type item #119295
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RalfJung commented Jul 24, 2019•
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