[release/9.0-staging] [wasm][AOT] fix codegen for small structs on stack #118416
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Co-authored-by: Larry Ewing <[email protected]>
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This was referenced Aug 6, 2025
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pavelsavara
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arch-wasm
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Tagging subscribers to 'arch-wasm': @lewing |
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/azp run runtime-wasm |
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Azure Pipelines could not run because the pipeline triggers exclude this branch/path. |
rbhanda
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Servicing-approved
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The fix worked
I don't know about packed SIMD, @lewing does it ring any bell ? |
pavelsavara
approved these changes
Aug 24, 2025
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/ba-g known CI issues for Net9 |
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Validation using System;
using System.Collections.Generic;
using System.Runtime.InteropServices.JavaScript;
using System.Threading.Tasks;
using System.Text;
using System.Buffers.Text;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Runtime.CompilerServices;
class Program
{
public static void Main()
{
Test(new string('\u0009', 1));
Test(new string('\u0009', 3));
Test(new string('\u000A', 1));
Test(new string('\u000A', 3));
Test(new string('\u000D', 1));
Test(new string('\u000D', 3));
Test(new string(' ', 1));
Test(new string(' ', 3));
}
[MethodImpl(MethodImplOptions.NoInlining)]
public static void Test(string utf8WithByteToBeIgnored){
ReadOnlySpan<char> utf8BytesWithByteToBeIgnored = utf8WithByteToBeIgnored.AsSpan();
bool isValid2 = Base64.IsValid(utf8BytesWithByteToBeIgnored, out int decodedLength);
Console.WriteLine($"IsValid2: {isValid2}, DecodedLength: {decodedLength}");
}
}<Project Sdk="Microsoft.NET.Sdk.WebAssembly">
<PropertyGroup>
<TargetFramework>net9.0</TargetFramework>
<AllowUnsafeBlocks>true</AllowUnsafeBlocks>
<RunAOTCompilation>true</RunAOTCompilation>
<WasmNativeDebugSymbols>true</WasmNativeDebugSymbols>
<WasmNativeStrip>false</WasmNativeStrip>
</PropertyGroup>
</Project> |
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Backport of #118355 to release/9.0-staging
/cc @lewing @pavelsavara
Customer Impact
Fixes incorrect AOT codegen on Wasm that could lead to memory corruption and hard to isolate failures.
[Select one or both of the boxes. Describe how this issue impacts customers, citing the expected and actual behaviors and scope of the issue. If customer-reported, provide the issue number.]
Regression
[If yes, specify when the regression was introduced. Provide the PR or commit if known.]
This case regressed in 9.0 development.
Testing
System.Buffers.Text.Tests.Base64ValidationUnitTests.ValidateWithOnlyCharsToBeIgnoredCharsRisk
Medium - AOT codegen is complex but the change impacts WASM AOT only, and only in the case of an empty struct, the previous codegen is known to be incorrect.