Fix WriteCompressedInt32 endianness on big-endian hosts by medhatiwari · Pull Request #984 · jbevain/cecil

medhatiwari · 2026-09-01T06:26:03Z

Cecil’s WriteUInt16/WriteUInt32 are always little-endian. WriteCompressedInt32 copied SRM’s IsLittleEndian check, so on big-endian it writes swapped compressed ints into portable PDBs.

That landed in dotnet/cecil via #505 (608fac6, originally jbevain/cecil#958) and flowed into the VMR in [dotnet/dotnet#8250](dotnet/dotnet#8250. Native s390x VMR Mono then fails in ILLink while trimming System.Runtime (IL1012, ArgumentNullException / document).

Always ReverseEndianness before those writes. Round-trip tests do not catch this on little-endian, the new test asserts spec bytes (-100 → BF39, -9076 → DFFFB919).

cc: @tmds

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This ensures that section starts are aligned by adjusting the previous Range's length to ensure the computed start of a new Range meets the alignment requirements. It was done this way rather than just computing an aligned start for the new Range, because the TextMap assumes that the Ranges are contiguous - see for example GetNextRVA.

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This ensures that section starts are aligned by adjusting the previous Range's length to ensure the computed start of a new Range meets the alignment requirements. It was done this way rather than just computing an aligned start for the new Range, because the TextMap assumes that the Ranges are contiguous - see for example GetNextRVA. GetNextRVA was used to compute the Code RVA, before adding that segment to the TextMap. This meant that the alignment (only added later) wasn't taken into account when writing out the code, but then later the TextMap was modified to include the alignment. This is fixed by first inserting an aligned zero-length Code segment before writing the code, then inserting it again once the length is known. Removing the Code alignment altogether would work too, but the alignment constants are kept in there, because it looks like they were added intentionally, even though the reason is unknown. Note that before this change, the start of the Code segment (at least on x64) was not 16-byte aligned in the first place, so this change will actually move the beginning of the Code segment.

[main] Update dependencies from dotnet/arcade - Merge branch 'main' into darc-main-236f6763-3a8c-439a-bd54-2abd86c5577b - Update test target to net8

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dotnet#79) Microsoft.SourceBuild.Intermediate.source-build-reference-packages From Version 8.0.0-alpha.1.23214.4 -> To Version 8.0.0-alpha.1.23221.1 Co-authored-by: dotnet-maestro[bot] <dotnet-maestro[bot]@users.noreply.github.com> Co-authored-by: Marek Safar <marek.safar@gmail.com>

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* Backflow from https://github.com/dotnet/dotnet / a9679a8 build 320973 Diff: https://github.com/dotnet/dotnet/compare/06787fc66d5364230924d00f2c5c251aeb7a31cd..a9679a8de87742e170318ea39f7f0e2874bcd441 From: dotnet/dotnet@06787fc To: dotnet/dotnet@a9679a8 [[ commit created by automation ]] * Update dependencies from build 320973 Updated Dependencies: Microsoft.DotNet.Arcade.Sdk (Version 11.0.0-beta.26313.102 -> 11.0.0-beta.26330.112) [[ commit created by automation ]] * Try if nodeReuse=false is breaking the Windows build * Update dependencies from build 321508 Updated Dependencies: Microsoft.DotNet.Arcade.Sdk (Version 11.0.0-beta.26330.112 -> 11.0.0-beta.26356.101) [[ commit created by automation ]] --------- Co-authored-by: dotnet-maestro[bot] <dotnet-maestro[bot]@users.noreply.github.com> Co-authored-by: Alexander Köplinger <alex.koeplinger@outlook.com>

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* Preserve document custom debug information Load custom debug information for every preserved portable PDB document so embedded sources survive a round trip. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 01ec6ff9-132e-45df-95c2-9cedbce405cb Assisted-by: GitHub Copilot CLI:GPT-5.6-Sol [code-review] * Hydrate document debug information when writing Read missing document custom debug information only when producing a portable PDB, and verify embedded sources survive after their sequence points are trimmed. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 01ec6ff9-132e-45df-95c2-9cedbce405cb Assisted-by: GitHub Copilot CLI:GPT-5.6-Sol [code-review] --------- Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 01ec6ff9-132e-45df-95c2-9cedbce405cb

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Merge in changes from upstream

Context: https://github.com/dotnet/roslyn/issues/80952 Context: unoplatform/uno#24036 Context: jbevain@608fac6 Context: jbevain#982 I've been trying to get a project building for iOS+Native AOT, which invariably would error out in `ilc`: Error: Sequence point value is out of range. System.BadImageFormatException: Sequence point value is out of range. at System.Reflection.Throw.SequencePointValueOutOfRange() in /_/src/runtime/src/libraries/System.Reflection.Metadata/src/System/Reflection/Throw.cs:line 239 at System.Reflection.Metadata.SequencePointCollection.Enumerator.MoveNext() in /_/src/runtime/src/libraries/System.Reflection.Metadata/src/System/Reflection/Metadata/PortablePdb/SequencePointCollection.cs:line 86 at Internal.TypeSystem.Ecma.PortablePdbSymbolReader.<GetSequencePointsForMethod>d__10.MoveNext() in /_/src/runtime/src/coreclr/tools/Common/TypeSystem/Ecma/SymbolReader/PortablePdbSymbolReader.cs:line 147 at ILCompiler.Logging.MessageOrigin..ctor(MethodIL, Int32) in /_/src/runtime/src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/Logging/MessageOrigin.cs:line 65 After quite a bit of investigation, determined that Cecil was apparent cause of the crash, because multiple "involved parties" did *not* have the fix present in commit jbevain/cecil@608fac6f, resulting in a "failure cascade": 1. `<Csc/>` task produces `.pdb` file 2. Uno `<EmbeddedResourceInjectorTask_v0/>` task uses Cecil to update (1), introduces "Invalid compressed integer". 3. `illink` -- which has its own copy of Cecil, from the dotnet/cecil fork -- consumes (2), turning "Invalid compressed integer" values into *different* values. 4. `ilc` processes `pdb` produced from (3), fails with `BadImageFormatException: Sequence point value is out of range`. A "full stack" fix involves updating Uno to use Mono.Cecil 0.11.6, which contains jbevain/cecil@608fac6f, *and also* updating `illink` to also contain the fix from jbevain/cecil@608fac6f. However, as part of this investigation, Claude cooked up a patch to dotnet/cecil along with unit test updates to ByteBufferTests. Of interest is that the suggested Claude fix for dotnet/cecil also causes the original ByteBufferTests test from jbevain/cecil@608fac6f to pass (yay), but not all of the new tests. Meanwhile, jbevain/cecil *does* pass all of the suggested new tests. Record the new tests for posterity, and to reduce future drift between jbevain/cecil and dotnet/cecil.

Updated Dependencies: Microsoft.DotNet.Arcade.Sdk (Version 11.0.0-beta.26381.101 -> 11.0.0-beta.26411.119) [[ commit created by automation ]] Co-authored-by: dotnet-maestro[bot] <dotnet-maestro[bot]@users.noreply.github.com>

* Enable AOT compatibility analysis Add a net8.0 analyzer target, make optional symbol provider lookup trim-safe, and annotate reflection import APIs that are incompatible with trimming. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 844b37b7-122c-40c2-a4c2-d499dd6e59bc * Use net10.0 for AOT analysis Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 844b37b7-122c-40c2-a4c2-d499dd6e59bc * Use framework compatibility for AOT analysis Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 844b37b7-122c-40c2-a4c2-d499dd6e59bc * Resolve modern framework warnings Use supported cryptography APIs, guard Windows-only CSP fallbacks, and exclude unsupported legacy reflection APIs from the net10 target. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 844b37b7-122c-40c2-a4c2-d499dd6e59bc * Ship trimming annotations for netstandard Polyfill RequiresUnreferencedCodeAttribute for older targets and emit reflection import annotations without target framework guards. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 844b37b7-122c-40c2-a4c2-d499dd6e59bc * Ship dynamic member annotations for netstandard Polyfill DynamicallyAccessedMembersAttribute and DynamicallyAccessedMemberTypes so symbol provider constructor requirements are emitted for older targets. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 844b37b7-122c-40c2-a4c2-d499dd6e59bc * Add compoent to explain * Update Mono.Cecil.csproj Co-authored-by: Alexander Köplinger <alex.koeplinger@outlook.com> --------- Co-authored-by: Alexander Köplinger <alex.koeplinger@outlook.com> Copilot-Session: 844b37b7-122c-40c2-a4c2-d499dd6e59bc

medhatiwari · 2026-09-01T06:30:33Z

This branch was reset to the dotnet/cecil-based commit so dotnet#517 could merge. The jbevain-based change is now in #985.

dotnet-maestro Bot and others added 30 commits December 26, 2022 13:38

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Fix WriteCompressedInt32 endianness on big-endian hosts

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medhatiwari force-pushed the fix-compressed-int32-be branch from 5e08e58 to 49cd6f9 Compare September 1, 2026 06:29

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Fix WriteCompressedInt32 endianness on big-endian hosts - #984

Fix WriteCompressedInt32 endianness on big-endian hosts#984
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