[release/9.0-staging] [wasm][AOT] fix codegen for small structs on stack

[github-actions]

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.

• Customer reported
• Found internally

[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

• Yes
• No

[If yes, specify when the regression was introduced. Provide the PR or commit if known.]

This case regressed in 9.0 development.

Testing

• Automated test System.Buffers.Text.Tests.Base64ValidationUnitTests.ValidateWithOnlyCharsToBeIgnoredChars
• manual testing in chrome dev tools debugger

Risk

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.

[dotnet-policy-service]

Tagging subscribers to 'arch-wasm': @lewing
See info in area-owners.md if you want to be subscribed.

[pavelsavara]

/azp run runtime-wasm

[azure-pipelines]

Azure Pipelines could not run because the pipeline triggers exclude this branch/path.

[pavelsavara]

The fix worked

System.Text.RegularExpressions.Tests failure is known #117557
DiagnosticMethodInfoTests.Create_StackFrame is #117165
NaN in System.Tests.HalfTests is #103347
There are also some infra failures.

Log

[20:51:53] info: Starting: System.Runtime.Intrinsics.Tests.dll [20:51:55] info: [FAIL] System.Runtime.Intrinsics.Wasm.Tests.PackedSimdTests.ComparisonWithNaNTest [20:51:55] info: Assert.Equal() Failure: Values differ [20:51:55] info: Expected: -Infinity [20:51:55] info: Actual: 1 [20:51:55] info: at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr) [20:51:55] info: [FAIL] System.Runtime.Intrinsics.Wasm.Tests.PackedSimdTests.ComparisonOperationsTest [20:51:55] info: Assert.Equal() Failure: Values differ [20:51:55] info: Expected: <1, 2, 2, 1> [20:51:55] info: Actual: <4, 3, 3, 4> [20:51:55] info: at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr) [20:51:55] info: [FAIL] System.Runtime.Intrinsics.Wasm.Tests.PackedSimdTests.MinMaxSignedUnsignedTest [20:51:55] info: Assert.Equal() Failure: Values differ [20:51:55] info: Expected: -1 [20:51:55] info: Actual: 0 [20:51:55] info: at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr) 

I don't know about packed SIMD, @lewing does it ring any bell ?

[pavelsavara]

/ba-g known CI issues for Net9

[pavelsavara]

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>