Revert "Improve cross-platform node discovery for reuse with NodeMode filtering"

[JanProvaznik]

Reverts #13256

Causes VS perf regression in loaded DLL count scenarios.

Copilot analysis:

Root Cause: WMI COM Interop for Process Command Line Retrieval

Commit c48fb46ac1 ("Improve cross-platform node discovery for reuse with NodeMode filtering") introduces direct WMI
COM interop in ProcessExtensions.Windows.GetCommandLine() to retrieve process command lines on Windows. This is the
chain:

Call Path

 1. NodeProviderOutOfProcBase → when nodeReuseRequested is true and ChangeWaves.Wave18_5 is enabled,
GetPossibleRunningNodes() now iterates candidate processes and calls:
 2. process.TryGetCommandLine() → on Windows, delegates to Windows.GetCommandLine(process.Id) which:
 3. Creates WMI COM objects via raw P/Invoke:
  - CoCreateInstance(CLSID_WbemLocator, ...) — instantiates the WMI locator
  - IWbemLocator.ConnectServer("ROOT\CIMV2", ...) — connects to WMI namespace
  - IWbemServices.ExecQuery("WQL", "SELECT CommandLine FROM Win32_Process WHERE ProcessId='...'") — queries process
info

Why Each DLL Gets Loaded

┌──────────────┬────────────────────────────────────────────────────────────────────────────────────────────────────
──────────────────────────────────────────────────────────────────────────┐
│ DLL          │ Reason
                                                                          │
├──────────────┼────────────────────────────────────────────────────────────────────────────────────────────────────
──────────────────────────────────────────────────────────────────────────┤
│ wbemcomn.dll │ WMI common infrastructure library — loaded when CoCreateInstance creates WbemLocator
                                                                          │
├──────────────┼────────────────────────────────────────────────────────────────────────────────────────────────────
──────────────────────────────────────────────────────────────────────────┤
│ wbemprox.dll │ WMI proxy — routes the ConnectServer("ROOT\CIMV2") call
                                                                          │
├──────────────┼────────────────────────────────────────────────────────────────────────────────────────────────────
──────────────────────────────────────────────────────────────────────────┤
│ wbemsvc.dll  │ WMI service support — backs the IWbemServices interface
                                                                          │
├──────────────┼────────────────────────────────────────────────────────────────────────────────────────────────────
──────────────────────────────────────────────────────────────────────────┤
│ fastprox.dll │ WMI fast proxy — provides the COM proxy stubs for IEnumWbemClassObject/IWbemClassObject enumeration
                                                                          │
├──────────────┼────────────────────────────────────────────────────────────────────────────────────────────────────
──────────────────────────────────────────────────────────────────────────┤
│ amsi.dll     │ Antimalware Scan Interface — Windows automatically loads this to scan WQL query strings executed
through WMI COM for malicious content (a Windows Defender security feature) │
└──────────────┴────────────────────────────────────────────────────────────────────────────────────────────────────
──────────────────────────────────────────────────────────────────────────┘
Summary

Before this commit, node discovery only called Process.GetProcessesByName(). After it, every candidate process
triggers a full WMI COM round-trip to read its command line for NodeMode filtering. This pulls the entire WMI stack
+ AMSI into the process address space. During VS tests where node reuse is enabled, this happens for every MSBuild
node provider initialization.

[JanProvaznik]

confirmed also by RPS trace analyzer

combase.dll!CoCreateInstanceEx
wbemprox.dll!
wbemprox.dll!
wbemprox.dll!
wbemprox.dll!
microsoft.build.dll!DomainBoundILStubClass.IL_STUB_CLRtoCOM
microsoft.build.dll!Microsoft.Build.Shared.ProcessExtensions+Windows.GetCommandLine
microsoft.build.dll!Microsoft.Build.Shared.ProcessExtensions.TryGetCommandLine
microsoft.build.dll!Microsoft.Build.BackEnd.NodeProviderOutOfProcBase.GetPossibleRunningNodes
microsoft.build.dll!Microsoft.Build.BackEnd.NodeProviderOutOfProcBase.GetNodes

[Copilot]

Pull request overview

This PR reverts PR #13256 ("Improve cross-platform node discovery for reuse with NodeMode filtering") because it caused a Visual Studio performance regression by loading WMI-related DLLs (wbemcomn.dll, wbemprox.dll, wbemsvc.dll, fastprox.dll, amsi.dll) on every MSBuild node provider initialization when node reuse was enabled.

Changes:

• Removes the WMI COM interop–based TryGetCommandLine / Windows.GetCommandLine implementation and related platform-specific (Linux /proc, macOS/BSD sysctl) command line retrieval code from ProcessExtensions.cs
• Removes NodeMode-based process filtering from GetPossibleRunningNodes in NodeProviderOutOfProcBase.cs and the ExtractFromCommandLine helper from NodeModeHelper, replacing it with a simpler inline regex in DebugUtils.cs
• Removes associated tests and cleans up AllowUnsafeBlocks, partial class modifiers, and [SupportedOSPlatformGuard] attributes that were no longer necessary

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/Shared/ProcessExtensions.cs	Removes all WMI/Linux/macOS command-line retrieval logic; restores to KillTree-only class
src/Build/BackEnd/Components/Communications/NodeProviderOutOfProcBase.cs	Removes NodeMode-based process filtering from GetPossibleRunningNodes; reverts to plain process-name lookup
src/Framework/NodeMode.cs	Removes ExtractFromCommandLine, ReadOnlySpan<char> overload, and partial keyword from NodeModeHelper
src/Shared/Debugging/DebugUtils.cs	Inlines a new ScanNodeMode local function to replace the removed NodeModeHelper.ExtractFromCommandLine
src/Framework/NativeMethods.cs	Removes [SupportedOSPlatformGuard] attributes from IsBSD and IsOSX (no longer needed without platform-specific dispatch)
src/Utilities.UnitTests/ProcessExtensions_Tests.cs	Removes TryGetCommandLine-related tests; keeps KillTree test
src/MSBuild.UnitTests/Microsoft.Build.CommandLine.UnitTests.csproj	Removes AllowUnsafeBlocks (no longer needed)
src/Tasks.UnitTests/Microsoft.Build.Tasks.UnitTests.csproj	Adds ProcessExtensions.cs compile include (re-adding shared file reference)
src/Framework.UnitTests/Microsoft.Build.Framework.UnitTests.csproj	Adds ProcessExtensions.cs compile include
src/Build.OM.UnitTests/Microsoft.Build.Engine.OM.UnitTests.csproj	Adds ProcessExtensions.cs compile include

[baronfel]

@JanProvaznik per internal chat we'd like to instead of reverting simply ifdef the change so that it only appears in core msbuild for now.