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Migrate GenerateReferencesStep from ILLink pipeline #24914

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Migrate GenerateReferencesStep from ILLink pipeline #24914

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28 changes: 23 additions & 5 deletions dotnet/targets/Xamarin.Shared.Sdk.targets
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@

<UsingTask TaskName="Xamarin.MacDev.Tasks.CompileNativeCode" AssemblyFile="$(_XamarinTaskAssembly)" />
<UsingTask TaskName="Xamarin.MacDev.Tasks.FindAotCompiler" AssemblyFile="$(_XamarinTaskAssembly)" />
<UsingTask TaskName="Xamarin.MacDev.Tasks.GenerateReferencesTask" AssemblyFile="$(_XamarinTaskAssembly)" />
<UsingTask TaskName="Xamarin.MacDev.Tasks.GetFullPaths" AssemblyFile="$(_XamarinTaskAssembly)" />
<UsingTask TaskName="Xamarin.MacDev.Tasks.InstallNameTool" AssemblyFile="$(_XamarinTaskAssembly)" />
<UsingTask TaskName="Xamarin.MacDev.Tasks.LinkNativeCode" AssemblyFile="$(_XamarinTaskAssembly)" />
Expand Down Expand Up @@ -261,6 +262,7 @@
_ComputeStripAssemblyIL;
_StripAssemblyIL;
_LoadLinkerOutput;
_GenerateReferences;
_CompileNativeExecutable;
_LinkNativeExecutable;
_ComputePublishLocation;
Expand Down Expand Up @@ -774,7 +776,7 @@
-->
<_TrimmerCustomSteps Include="$(_AdditionalTaskAssembly)" Type="Xamarin.Linker.RegistrarStep" />
<_TrimmerCustomSteps Include="$(_AdditionalTaskAssembly)" Type="Xamarin.GenerateMainStep" />
<_TrimmerCustomSteps Include="$(_AdditionalTaskAssembly)" Type="Xamarin.GenerateReferencesStep" />
<!-- GenerateReferencesStep has been migrated to a standalone MSBuild task (_GenerateReferences target) -->
<_TrimmerCustomSteps Include="$(_AdditionalTaskAssembly)" Type="Xamarin.GatherFrameworksStep" />
<_TrimmerCustomSteps Include="$(_AdditionalTaskAssembly)" Type="Xamarin.Linker.ComputeNativeBuildFlagsStep" />
<_TrimmerCustomSteps Include="$(_AdditionalTaskAssembly)" Type="Xamarin.Linker.ComputeAOTArguments" />
Expand Down Expand Up @@ -1055,8 +1057,7 @@
<_LinkerItemFiles Include="$(_LinkerItemsDirectory)/_MainLinkerFlags.items" />
<_LinkerItemFiles Include="$(_LinkerItemsDirectory)/_BindingLibraryFrameworks.items" />
<_LinkerItemFiles Include="$(_LinkerItemsDirectory)/_RegistrarFile.items" />
<_LinkerItemFiles Include="$(_LinkerItemsDirectory)/_ReferencesFile.items" />
<_LinkerItemFiles Include="$(_LinkerItemsDirectory)/ReferenceNativeSymbol.items" />
<_LinkerItemFiles Include="$(_LinkerItemsDirectory)/_RequiredNativeReference.items" />
<_LinkerItemFiles Include="$(_LinkerItemsDirectory)/_AssembliesToAOT.items" />
<_LinkerItemFiles Include="$(_LinkerItemsDirectory)/_FrameworkToPublish.items" />
<_LinkerItemFiles Include="$(_LinkerItemsDirectory)/_DynamicLibraryToPublish.items" />
Expand All @@ -1079,14 +1080,31 @@
<_MainLinkerFlags Include="@(_AllLinkerItems)" Condition="'%(_AllLinkerItems.SourceFile)' == '_MainLinkerFlags.items'" />
<_BindingLibraryFrameworks Include="@(_AllLinkerItems)" Condition="'%(_AllLinkerItems.SourceFile)' == '_BindingLibraryFrameworks.items'" />
<_RegistrarFile Include="@(_AllLinkerItems)" Condition="'%(_AllLinkerItems.SourceFile)' == '_RegistrarFile.items'" />
<_ReferencesFile Include="@(_AllLinkerItems)" Condition="'%(_AllLinkerItems.SourceFile)' == '_ReferencesFile.items'" />
<_ProcessedReferenceNativeSymbol Include="@(_AllLinkerItems)" Condition="'%(_AllLinkerItems.SourceFile)' == 'ReferenceNativeSymbol.items'" />
<_RequiredNativeReference Include="@(_AllLinkerItems)" Condition="'%(_AllLinkerItems.SourceFile)' == '_RequiredNativeReference.items'" />
<_AssembliesToAOT Include="@(_AllLinkerItems)" Condition="'%(_AllLinkerItems.SourceFile)' == '_AssembliesToAOT.items'" />
<_FrameworkToPublish Include="@(_AllLinkerItems)" Condition="'%(_AllLinkerItems.SourceFile)' == '_FrameworkToPublish.items'" />
<_DynamicLibraryToPublish Include="@(_AllLinkerItems)" Condition="'%(_AllLinkerItems.SourceFile)' == '_DynamicLibraryToPublish.items'" />
</ItemGroup>
</Target>

<!--
Generate native symbol references.
This target replaces the GenerateReferencesStep ILLink step.
It processes the _RequiredNativeReference items collected during linking
and produces either _ReferencesFile (Code mode) or _ProcessedReferenceNativeSymbol (Linker mode) items.
-->
<Target Name="_GenerateReferences" DependsOnTargets="_LoadLinkerOutput" Condition="'$(IsMacEnabled)' == 'true'">
<GenerateReferencesTask
SessionId="$(BuildSessionId)"
RequiredSymbols="@(_RequiredNativeReference)"
SymbolMode="Linker"
CacheDirectory="$(_LinkerCacheDirectory)"
>
<Output TaskParameter="ReferencesFile" ItemName="_ReferencesFile" />
<Output TaskParameter="NativeSymbols" ItemName="_ProcessedReferenceNativeSymbol" />
</GenerateReferencesTask>
</Target>

<!-- Native code -->

<Target Name="_ComputeFrameworkVariables" DependsOnTargets="ResolveRuntimePackAssets;ResolveFrameworkReferences">
Expand Down
183 changes: 183 additions & 0 deletions msbuild/Xamarin.MacDev.Tasks/Tasks/GenerateReferencesTask.cs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,183 @@
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;

using Microsoft.Build.Framework;
using Microsoft.Build.Utilities;

#nullable enable

namespace Xamarin.MacDev.Tasks {
// This task replaces the GenerateReferencesStep ILLink step.
// It processes native symbols collected during linking and either:
// - Generates an Objective-C reference source file (Code mode), or
// - Passes symbols through as MSBuild items for the native linker (Linker mode)
public class GenerateReferencesTask : XamarinTask {

#region Inputs

// Native symbols collected during linking (from _RequiredNativeReference items).
// Each item has Identity = "_" + symbolName, and metadata: SymbolType (Function/ObjectiveCClass/Field), SymbolMode (Default/Linker/Code/Ignore)
public ITaskItem [] RequiredSymbols { get; set; } = Array.Empty<ITaskItem> ();

// The symbol mode: "Linker", "Code", or "Ignore".
[Required]
public string SymbolMode { get; set; } = string.Empty;

// The directory to write the reference.m file to (used in Code mode).
public string CacheDirectory { get; set; } = string.Empty;

#endregion

#region Outputs

// In Code mode: the generated reference.m file path.
[Output]
public ITaskItem [] ReferencesFile { get; set; } = Array.Empty<ITaskItem> ();

// In Linker mode: the native symbols to pass to the native linker.
[Output]
public ITaskItem [] NativeSymbols { get; set; } = Array.Empty<ITaskItem> ();

#endregion

public override bool Execute ()
{
// Filter out symbols with SymbolMode == Ignore
var symbols = RequiredSymbols
.Where (s => !string.Equals (s.GetMetadata ("SymbolMode"), "Ignore", StringComparison.OrdinalIgnoreCase))
.ToArray ();

switch (SymbolMode) {
case "Ignore":
break;
case "Code":
ExecuteCodeMode (symbols);
break;
case "Linker":
ExecuteLinkerMode (symbols);
break;
default:
Log.LogError ("Invalid symbol mode: {0}", SymbolMode);
return false;
}

return !Log.HasLoggedErrors;
}

void ExecuteLinkerMode (ITaskItem [] symbols)
{
// In Linker mode, pass through the symbols as ReferenceNativeSymbol items.
// The Identity is already in "_symbolName" format from the linker output.
var items = new List<TaskItem> ();
foreach (var symbol in symbols) {
var item = new TaskItem (symbol.ItemSpec);
item.SetMetadata ("SymbolType", symbol.GetMetadata ("SymbolType"));
items.Add (item);
}
NativeSymbols = items.ToArray ();
}

void ExecuteCodeMode (ITaskItem [] symbols)
{
var reference_m = Path.Combine (CacheDirectory, "reference.m");

if (symbols.Length == 0) {
if (File.Exists (reference_m))
File.Delete (reference_m);
ReferencesFile = Array.Empty<ITaskItem> ();
return;
}

var sb = new StringBuilder ();
sb.AppendLine ("#import <Foundation/Foundation.h>");

// Emit declarations
foreach (var symbol in symbols) {
var symbolType = symbol.GetMetadata ("SymbolType");
var name = GetSymbolName (symbol);
var objcName = GetObjectiveCName (symbol);

switch (symbolType) {
case "Function":
case "Field":
sb.Append ("extern void * ").Append (name).AppendLine (";");
break;
case "ObjectiveCClass":
sb.AppendLine ($"@interface {objcName} : NSObject @end");
break;
default:
Log.LogError ("Invalid symbol type {0} for symbol {1}", symbolType, symbol.ItemSpec);
return;
}
}

// Emit the referencing function
sb.AppendLine ("static void __xamarin_symbol_referencer () __attribute__ ((used)) __attribute__ ((optnone));");
sb.AppendLine ("void __xamarin_symbol_referencer ()");
sb.AppendLine ("{");
sb.AppendLine ("\tvoid *value;");

foreach (var symbol in symbols) {
var symbolType = symbol.GetMetadata ("SymbolType");
var name = GetSymbolName (symbol);
var objcName = GetObjectiveCName (symbol);

switch (symbolType) {
case "Function":
case "Field":
sb.AppendLine ($"\tvalue = {name};");
break;
case "ObjectiveCClass":
sb.AppendLine ($"\tvalue = [{objcName} class];");
break;
default:
Log.LogError ("Invalid symbol type {0} for symbol {1}", symbolType, symbol.ItemSpec);
return;
}
}

sb.AppendLine ("}");
sb.AppendLine ();

Directory.CreateDirectory (CacheDirectory);
WriteIfDifferent (reference_m, sb.ToString ());

ReferencesFile = new ITaskItem [] { new TaskItem (reference_m) };
}

// The item Identity is in "_symbolName" format (with "_" prefix).
// For the .m file, we need the name WITHOUT the leading "_" prefix.
static string GetSymbolName (ITaskItem symbol)
{
var identity = symbol.ItemSpec;
// Strip the "_" prefix that was added by the linker step
if (identity.StartsWith ("_", StringComparison.Ordinal))
return identity.Substring (1);
return identity;
}

const string ObjectiveCPrefix = "OBJC_CLASS_$_";

// Extract the Objective-C class name from a symbol like "_OBJC_CLASS_$_ClassName"
static string GetObjectiveCName (ITaskItem symbol)
{
var name = GetSymbolName (symbol);
if (name.StartsWith (ObjectiveCPrefix, StringComparison.Ordinal))
return name.Substring (ObjectiveCPrefix.Length);
return name;
}

static void WriteIfDifferent (string path, string contents)
{
if (File.Exists (path)) {
var existing = File.ReadAllText (path);
if (existing == contents)
return;
}
File.WriteAllText (path, contents);
}
}
}
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