layout: Store inverse memory index in `FieldsShape::Arbitrary`#150116

moulins · 2025-12-17T23:37:18Z

All usages of memory_index start by calling invert_bijective_mapping, so storing the inverted mapping directly saves some work and simplifies the code.

rustbot · 2025-12-17T23:37:22Z

The Miri subtree was changed

cc @rust-lang/miri

Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

Some changes occurred to the CTFE / Miri interpreter

cc @rust-lang/miri

rustbot · 2025-12-17T23:37:25Z

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workingjubilee · 2025-12-18T00:40:33Z

huh. I wonder what it's inverted relative to?

workingjubilee · 2025-12-18T01:06:25Z

@moulins I have no objection to the substance of the change but "inverse" suggests a relativeness this doesn't capture... IMO this is still just a "memory index" until you do something like specify the other half of the pair, whether it's the key or value, at which point they might adopt a logical ordering.

mem_src_field_index maybe? idk.

workingjubilee · 2025-12-18T01:08:58Z

kinda curious if this has any effect on perf or if it's just logical cleanup

@bors try @rust-timer queue

layout: Store inverse memory index in `FieldsShape::Arbitrary`

moulins · 2025-12-18T01:31:06Z

I have no objection to the substance of the change but "inverse" suggests a relativeness this doesn't capture... IMO this is still just a "memory index" until you do something like specify the other half of the pair, whether it's the key or value, at which point they might adopt a logical ordering.

mem_src_field_index maybe? idk

Hm, good point... what about in_memory_order?

workingjubilee · 2025-12-18T01:58:13Z

something like that sounds good to me!

rust-bors · 2025-12-18T03:24:22Z

☀️ Try build successful (CI)
Build commit: ed52dc8 (ed52dc8f27781eef22c18d699984ef94c758cc92, parent: f794a08738958bbef01c3dcab34ec21d3da1e51a)

rust-timer · 2025-12-18T04:19:17Z

Finished benchmarking commit (ed52dc8): comparison URL.

Overall result: ✅ improvements - no action needed

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

@bors rollup=never
@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

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	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.1%	[-0.2%, -0.0%]	2
All ❌✅ (primary)	-	-	0

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	mean	range	count
Regressions ❌ (primary)	1.8%	[1.8%, 1.8%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.8%	[1.8%, 1.8%]	1

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	mean	range	count
Regressions ❌ (primary)	2.3%	[2.3%, 2.3%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.3%	[2.3%, 2.3%]	1

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Bootstrap: 481.694s -> 485.432s (0.78%)
Artifact size: 390.59 MiB -> 390.53 MiB (-0.01%)

RalfJung · 2025-12-18T06:57:18Z

-            FieldsShape::Arbitrary { memory_index, .. } => {
-                for idx in Self::aggregate_field_iter(memory_index) {
+            FieldsShape::Arbitrary { inverse_memory_index, .. } => {
+                for idx in Self::aggregate_field_iter(inverse_memory_index) {


If iterating in memory order is now cheap, maybe we should just always do that... in fact that could unlock a bunch of follow-up cleanup here. Probably best to make all that a follow-up PR, but a good indication that this PR moves us in the right direction. :)

So you'd propose removing aggregate_field_iter entirely and and simply iterate the fields directly?

Yes. But I would suggest doing it in a separate PR so we can separately benchmark that change.

moulins · 2025-12-18T14:12:36Z

Renamed inverse_memory_index to in_memory_order, and updated some UI tests that I missed previously.

EDIT: I just noticed that rust-analyzer has its own version of FieldsShape, should I perform the same change here too?

workingjubilee · 2025-12-18T18:07:26Z

@moulins I don't think this type is related in a meaningful way? https://github.com/rust-lang/rust/blob/main/src/tools/rust-analyzer/crates/hir-def/src/item_tree.rs#L519

Do you mean something else?

workingjubilee · 2025-12-18T20:31:49Z

To be clear, I am 100% certain that rust-analyzer uses rustc_abi::FieldsShape also but have no idea what uses need to be changed if any.

moulins · 2025-12-18T21:04:38Z

You're totally right; from what I can see, the uses are here in Layout::{tail_padding, largest_padding}, but for some reason my ./x check still succeeds and trying to rename these uses causes an error.

All usages of `memory_index` start by calling `invert_bijective_mapping`, so storing the inverted mapping directly saves some work and simplifies the code.

bors · 2025-12-19T15:34:56Z

📌 Commit b31ee3a has been approved by workingjubilee

It is now in the queue for this repository.

…=workingjubilee layout: Store inverse memory index in `FieldsShape::Arbitrary` All usages of `memory_index` start by calling `invert_bijective_mapping`, so storing the inverted mapping directly saves some work and simplifies the code.

Rollup of 7 pull requests Successful merges: - #149633 (Enable `outline-atomics` by default on AArch64 FreeBSD) - #149788 (Move shared offload globals and define per-kernel globals once) - #149989 (Improve filenames encoding and misc) - #150012 (rustc_target: Add `efiapi` ABI support for LoongArch) - #150116 (layout: Store inverse memory index in `FieldsShape::Arbitrary`) - #150151 (Destabilise `target-spec-json`) - #150159 (Split eii macro expansion code) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 6 pull requests Successful merges: - #149633 (Enable `outline-atomics` by default on AArch64 FreeBSD) - #149788 (Move shared offload globals and define per-kernel globals once) - #149989 (Improve filenames encoding and misc) - #150012 (rustc_target: Add `efiapi` ABI support for LoongArch) - #150116 (layout: Store inverse memory index in `FieldsShape::Arbitrary`) - #150159 (Split eii macro expansion code) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #150116 - moulins:layout-inv-memory-index, r=workingjubilee layout: Store inverse memory index in `FieldsShape::Arbitrary` All usages of `memory_index` start by calling `invert_bijective_mapping`, so storing the inverted mapping directly saves some work and simplifies the code.

…utine layout This commit fixes a critical bug introduced in PR rust-lang#150116 that caused "offset is not a multiple of 16" errors when compiling for x86_64-unknown-uefi. Problem: -------- PR rust-lang#150116 optimized memory layout by inverting the storage representation from `memory_index` (source→memory) to `in_memory_order` (memory→source). However, in compiler/rustc_abi/src/layout/coroutine.rs (lines 244-276), the code was building `combined_in_memory_order` directly instead of: 1. Building `combined_memory_index` (source→memory) first 2. Inverting it to get `in_memory_order` (memory→source) This caused fields to be placed at incorrect offsets, violating PE/COFF alignment requirements (16-byte multiples), triggering linker errors. Solution: --------- Changed the coroutine layout code to: - Build `combined_memory_index` as an intermediate representation - Use correct indexing: `combined_memory_index[i] = memory_index` - Invert at the end: `combined_in_memory_order = combined_memory_index.invert_bijective_mapping()` Impact: ------- - Fixes UEFI target compilation (x86_64-unknown-uefi) - May affect other PE/COFF targets - Enables SOBEX OS development to continue Files changed: -------------- - compiler/rustc_abi/src/layout/coroutine.rs: Applied fix - BUG_FIX_REPORT.md: Detailed investigation report - fix_pr150116_coroutine_layout.patch: Patch for upstream submission - .gitignore: Added Claude Code settings Upstream: --------- This fix should be submitted to rust-lang/rust as it affects the latest nightly (2025-12-19) and potentially other PE/COFF targets. 🤖 Generated with Claude Code Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Rollup of 6 pull requests Successful merges: - rust-lang/rust#149633 (Enable `outline-atomics` by default on AArch64 FreeBSD) - rust-lang/rust#149788 (Move shared offload globals and define per-kernel globals once) - rust-lang/rust#149989 (Improve filenames encoding and misc) - rust-lang/rust#150012 (rustc_target: Add `efiapi` ABI support for LoongArch) - rust-lang/rust#150116 (layout: Store inverse memory index in `FieldsShape::Arbitrary`) - rust-lang/rust#150159 (Split eii macro expansion code) r? `@ghost` `@rustbot` modify labels: rollup

PR rust-lang#150116 introduced a bug in coroutine variant layout by incorrectly building the `in_memory_order` mapping directly instead of building an intermediate `memory_index` and inverting it. The bug caused fields to be placed at incorrect memory offsets, violating alignment requirements. This manifested as linker errors on PE/COFF targets (e.g., x86_64-unknown-uefi): error: offset is not a multiple of 16 Fix by correctly building `combined_memory_index` (source→memory) as an intermediate representation, then inverting it to get `combined_in_memory_order` (memory→source).

PR rust-lang#150116 introduced a bug in coroutine variant layout by incorrectly keeping the direct construction of `in_memory_order` without adapting it to the new representation. Before PR rust-lang#150116, the code correctly built an inverse mapping indexed by memory position, then inverted it to get the memory_index. After PR rust-lang#150116, the code still built the mapping indexed by memory position (as if it were an inverse mapping), but treated it directly as `in_memory_order` without inversion. This caused incorrect field ordering. The bug manifested as linker errors on PE/COFF targets (e.g., x86_64-unknown-uefi): error: offset is not a multiple of 16 And as ICEs with non-bijective mapping assertions in other cases. Fix by correctly keeping the inverse memory index construction (indexed by memory position), then using it directly as `in_memory_order` since that's what the new representation expects.

Rollup of 6 pull requests Successful merges: - rust-lang/rust#149633 (Enable `outline-atomics` by default on AArch64 FreeBSD) - rust-lang/rust#149788 (Move shared offload globals and define per-kernel globals once) - rust-lang/rust#149989 (Improve filenames encoding and misc) - rust-lang/rust#150012 (rustc_target: Add `efiapi` ABI support for LoongArch) - rust-lang/rust#150116 (layout: Store inverse memory index in `FieldsShape::Arbitrary`) - rust-lang/rust#150159 (Split eii macro expansion code) r? `@ghost` `@rustbot` modify labels: rollup

Adapt kani-compiler to the rustc/rustc_public API changes in this window: - rust-lang/rust#148766 (mir-const-runtime-checks): `Rvalue::NullaryOp` and `NullOp` were removed; `SizeOf`/`AlignOf`/`OffsetOf` become `mir::ConstValue` and the `ub_checks`/`contract_checks`/`overflow_checks` flags move to a new `Operand::RuntimeChecks(RuntimeChecks)`. Drop the `NullaryOp` match arms and handle `Operand::RuntimeChecks` everywhere `Operand` is matched (codegen it to `false`, as the old `NullOp::RuntimeChecks` was; treat it as a no-op in the points-to / uninit / MIR-internalization visitors). - rust-lang/rust#150116: `FieldsShape::Arbitrary::memory_index` renamed to `in_memory_order` (Kani only uses its length). - New `ValueAbi::ScalableVector` variant handled in the valid-value analysis. - rust-lang/rust#6d6068f6c5b (stabilize annotate-snippet): `HumanReadableErrorType` became a struct `{ short, unicode }` instead of an enum with a `Default` variant. Main suites pass on 12-31: expected (458), ui (144), kani (589), 0 failures. Co-authored-by: Kiro <kiro-agent@users.noreply.github.com>

Upgrade the toolchain to `nightly-2025-12-31` and adapt Kani to the corresponding `rustc`/`rustc_public` changes: - **Crate-qualified names** (rust-lang/rust#149401): `name()` now qualifies local items with the crate name. Add a `strip_local_crate_prefix` helper and keep harness/function/static pretty names, the recursion-tracker `--nondet-static-exclude`, stubbing diagnostics, and the autoharness/`list` output crate-relative; fix the automatic contract-harness lookup accordingly. - **MIR runtime checks** (rust-lang/rust#148766): `Rvalue::NullaryOp`/`NullOp` were removed and the `ub`/`contract`/`overflow` checks moved to `Operand::RuntimeChecks`; update the CPROVER and LLBC codegen and the related analyses. - **`unsized_fn_params`**: the updated std passes unsized values by value (e.g. `impl … for [&str]`). Represent unsized-by-value arguments as fat pointers so they codegen instead of triggering an ICE (test under `tests/kani/UnsizedFnParams`). - Smaller adaptations: `FieldsShape::…::in_memory_order` (rust-lang/rust#150116), the new `ValueAbi::ScalableVector` variant, the `HumanReadableErrorType` struct form, coercion/safety cleanups (rust-lang/rust#148602), a refreshed `pointer_generator_error` expected file, and a `clippy::result_large_err` allow. Resolves: model-checking#4623 By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 and MIT licenses. --------- Co-authored-by: Kiro <kiro-agent@users.noreply.github.com>

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moulins force-pushed the layout-inv-memory-index branch from c3ca7dc to 8db435e Compare December 18, 2025 00:12

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rust-bors Bot added a commit that referenced this pull request Dec 18, 2025

Auto merge of #150116 - moulins:layout-inv-memory-index, r=<try>

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layout: Store inverse memory index in `FieldsShape::Arbitrary`

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layout: Store inverse memory index in FieldsShape::Arbitrary

b31ee3a

All usages of `memory_index` start by calling `invert_bijective_mapping`, so storing the inverted mapping directly saves some work and simplifies the code.

moulins force-pushed the layout-inv-memory-index branch from e0bc269 to b31ee3a Compare December 18, 2025 21:26

rustbot assigned workingjubilee and unassigned nnethercote Dec 19, 2025

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 Dec 19, 2025

matthiaskrgr mentioned this pull request Dec 19, 2025

Rollup of 6 pull requests #150167

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matthiaskrgr mentioned this pull request Dec 19, 2025

Rollup of 7 pull requests #150168

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matthiaskrgr mentioned this pull request Dec 19, 2025

Rollup of 6 pull requests #150177

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bors merged commit 22440fd into rust-lang:main Dec 20, 2025
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moulins deleted the layout-inv-memory-index branch December 20, 2025 13:33

leonardocxavier mentioned this pull request Dec 22, 2025

Fix PR #150116 bug: incorrect memory index inversion in coroutine layout #150266

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leonardocxavier mentioned this pull request Dec 22, 2025

Fix coroutine layout bug from PR #150116 #150275

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github-actions Bot mentioned this pull request Dec 23, 2025

Toolchain upgrade to nightly-2026-02-09 flux-rs/flux#1345

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tautschnig mentioned this pull request Jul 9, 2026

Upgrade Rust toolchain to 2025-12-31 model-checking/kani#4624

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Overall result: ✅ improvements - no action needed

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