add rustc_abi(assert_eq) to test some guaranteed or at least highly expected ABI compatibility guarantees #115372

RalfJung · 2023-08-30T09:16:12Z

This new repr(transparent) test is super useful, it would have found #115336 and found #115404, #115481, #115509.

rustbot · 2023-08-30T09:16:17Z

(rustbot has picked a reviewer for you, use r? to override)

RalfJung · 2023-08-30T09:20:06Z

tests/ui/abi/transparent.rs

+test_transparent!(pair, (i32, f32));
+test_transparent!(tuple, (i32, f32, i64, f64));
+test_transparent!(zst, ());
+test_transparent!(empty_array, [u32; 0]);


I expect this will fail on some targets due to #115336. However that's a tier 2 target so I think we don't run tests?

RalfJung · 2023-08-30T12:00:12Z

tests/codegen/repr/transparent.rs

@@ -43,7 +43,6 @@ pub extern "C" fn test_WithZst(_: WithZst) -> WithZst { loop {} }
 #[repr(transparent)]
 pub struct WithZeroSizedArray(*const f32, [i8; 0]);

-// Apparently we use i32* when newtype-unwrapping f32 pointers. Whatever.


This comment seems to be from a time when LLVM still had pointee types, so I think it can be removed.

rustbot · 2023-09-02T10:03:58Z

Some changes occurred to the CTFE / Miri engine

cc @rust-lang/miri

add rustc_abi(assert_eq) to test some guaranteed or at least highly expected ABI compatibility guarantees This new repr(transparent) test is super useful, it would have found rust-lang#115336 and found rust-lang#115404, rust-lang#115481, rust-lang#115509.

bors · 2023-09-08T10:06:34Z

💔 Test failed - checks-actions

RalfJung · 2023-09-08T11:26:19Z

It also fails on arm, not just aarch64
@bors r=davidtwco

bors · 2023-09-08T11:26:20Z

📌 Commit e726be2 has been approved by davidtwco

It is now in the queue for this repository.

bors · 2023-09-08T11:56:12Z

⌛ Testing commit e726be2 with merge cd71a37...

bors · 2023-09-08T13:42:59Z

☀️ Test successful - checks-actions
Approved by: davidtwco
Pushing cd71a37 to master...

rust-timer · 2023-09-08T15:08:14Z

Finished benchmarking commit (cd71a37): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results

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	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.0%	[0.6%, 4.4%]	5
Improvements ✅ (primary)	-1.2%	[-1.5%, -0.9%]	2
Improvements ✅ (secondary)	-2.3%	[-2.3%, -2.3%]	1
All ❌✅ (primary)	-1.2%	[-1.5%, -0.9%]	2

Cycles

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Bootstrap: 629.695s -> 631.473s (0.28%)
Artifact size: 318.12 MiB -> 318.18 MiB (0.02%)

Support Result<T, E> across FFI when niche optimization can be used Allow allow enums like `Result<T, E>` to be used across FFI if the T/E can be niche optimized and the non-niche-optimized type is FFI safe. Implementation of rust-lang/rfcs#3391 Tracking issue: rust-lang#110503 Additional ABI and codegen tests were added in rust-lang#115372

Support Result<T, E> across FFI when niche optimization can be used (v2) This PR is identical to rust-lang#122253, which was approved and merged but then removed from master by a force-push due to a [CI bug](https://rust-lang.zulipchat.com/#narrow/stream/242791-t-infra/topic/ci.20broken.3F). r? ghost Original PR description: --- Allow allow enums like `Result<T, E>` to be used across FFI if the T/E can be niche optimized and the non-niche-optimized type is FFI safe. Implementation of rust-lang/rfcs#3391 Tracking issue: rust-lang#110503 Additional ABI and codegen tests were added in rust-lang#115372

Support Result<T, E> across FFI when niche optimization can be used (v2) This PR is identical to #122253, which was approved and merged but then removed from master by a force-push due to a [CI bug](https://rust-lang.zulipchat.com/#narrow/stream/242791-t-infra/topic/ci.20broken.3F). r? ghost Original PR description: --- Allow allow enums like `Result<T, E>` to be used across FFI if the T/E can be niche optimized and the non-niche-optimized type is FFI safe. Implementation of rust-lang/rfcs#3391 Tracking issue: rust-lang/rust#110503 Additional ABI and codegen tests were added in rust-lang/rust#115372

rustbot assigned davidtwco Aug 30, 2023

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Aug 30, 2023

RalfJung commented Aug 30, 2023

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RalfJung force-pushed the abi-assert-eq branch 2 times, most recently from 072bfa5 to 3a81c97 Compare August 30, 2023 11:55

RalfJung commented Aug 30, 2023

View reviewed changes

RalfJung mentioned this pull request Aug 30, 2023

extern "C" fn on sparc64 targets does not respect repr(transparent) #115336

Open

RalfJung force-pushed the abi-assert-eq branch from e26a5f6 to ec75ba4 Compare August 31, 2023 07:27

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This was referenced Aug 31, 2023

extern "C" fn on mips64 targets does not respect repr(transparent) #115404

Open

Tracking Issue for result_ffi_guarantees (RFC 3391) #110503

Closed

RalfJung force-pushed the abi-assert-eq branch 5 times, most recently from 57dce60 to 170df61 Compare September 2, 2023 10:03

RalfJung changed the title ~~add rustc_abi(assert_eq) to test some repr(transparent) cases~~ add rustc_abi(assert_eq) to test some guaranteed or at least highly expected ABI compatibility guarantees Sep 2, 2023

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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 Sep 8, 2023

need to disable part of this test on arm

e726be2

RalfJung force-pushed the abi-assert-eq branch from bd13b26 to e726be2 Compare September 8, 2023 11:26

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 Sep 8, 2023

bors added the merged-by-bors This PR was explicitly merged by bors. label Sep 8, 2023

bors merged commit cd71a37 into rust-lang:master Sep 8, 2023

rustbot added this to the 1.74.0 milestone Sep 8, 2023

RalfJung deleted the abi-assert-eq branch September 8, 2023 13:45

bors mentioned this pull request Sep 8, 2023

improve PassMode docs #115654

Merged

MasterAwesome mentioned this pull request Mar 9, 2024

Support Result<T, E> across FFI when niche optimization can be used #122253

Merged

dtolnay mentioned this pull request May 5, 2024

Support Result<T, E> across FFI when niche optimization can be used (v2) #124747

Merged

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add rustc_abi(assert_eq) to test some guaranteed or at least highly expected ABI compatibility guarantees #115372

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