Add an option to not generate precise GC info

eng/testing/tests.singlefile.targets

@@ -1,5 +1,7 @@
 <Project>
   <PropertyGroup>
+    <IlcUseConservativeGc>true</IlcUseConservativeGc>
+
     <OutputType>Exe</OutputType>
 
     <DefineConstants>$(DefineConstants);SINGLE_FILE_TEST_RUNNER</DefineConstants>

src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.targets

@@ -256,6 +256,9 @@ The .NET Foundation licenses this file to you under the MIT license.
       <IlcArg Condition="'$(TrimmerDefaultAction)' == 'copyused' or '$(TrimmerDefaultAction)' == 'copy' or '$(TrimMode)' == 'partial'" Include="--defaultrooting" />
       <IlcArg Include="--resilient" />
 
+      <IlcArg Condition="'$(IlcUseConservativeGc)' == 'true'" Include="--runtimeopt:gcConservative=1" />
+      <IlcArg Condition="'$(IlcUseConservativeGc)' == 'true'" Include="--noprecisegc" />
+
       <IlcArg Condition="$(IlcDisableReflection) == 'true'" Include="--feature:System.Reflection.IsReflectionExecutionAvailable=false" />
 
       <!-- Configure LINQ expressions - disable Emit everywhere -->

src/coreclr/nativeaot/docs/optimizing.md

@@ -35,6 +35,7 @@ Since `PublishTrimmed` is implied to be true with Native AOT, some framework fea
 ## Options related to metadata generation
 
 * `<IlcGenerateStackTraceData>false</IlcGenerateStackTraceData>`: this disables generation of stack trace metadata that provides textual names in stack traces. This is for example the text string one gets by calling `Exception.ToString()` on a caught exception. With this option disabled, stack traces will still be generated, but will be based on reflection metadata alone (they might be less complete).
+* `<IlcUseConservativeGc>`: if set to `true`, conservative GC stack scanning will be used and metadata related to GC stack reporting will not be generated. The generated executable file will be smaller, but the GC will be less efficient (garbage collection might take longer and keep objects alive for longer periods of time than usual).
 
 ## Options related to code generation
 * `<IlcOptimizationPreference>Speed</IlcOptimizationPreference>`: when generating optimized code, favor code execution speed.

src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/CompilationBuilder.Aot.cs

@@ -23,6 +23,7 @@ public partial class CompilationBuilder
         protected InstructionSetSupport _instructionSetSupport;
         protected SecurityMitigationOptions _mitigationOptions;
         protected bool _useDwarf5;
+        protected bool _isPreciseGc = true;
 
         partial void InitializePartial()
         {
@@ -108,6 +109,12 @@ public CompilationBuilder UseDwarf5(bool value)
             return this;
         }
 
+        public CompilationBuilder UseGCStackReporting(bool isPrecise)
+        {
+            _isPreciseGc = isPrecise;
+            return this;
+        }
+
         protected PreinitializationManager GetPreinitializationManager()
         {
             if (_preinitializationManager == null)

src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/DependencyAnalysis/ObjectWriter.cs

@@ -559,7 +559,7 @@ public void PublishUnwindInfo(ObjectNode node)
                     ehInfo = null;
                 }
 
-                if (gcInfo != null)
+                if (gcInfo != null && ((_options & ObjectWritingOptions.NoGcInfo) == 0))
                 {
                     EmitBlob(gcInfo);
                     gcInfo = null;
@@ -645,7 +645,7 @@ public void BuildCFIMap(NodeFactory factory, ObjectNode node)
                     ehInfo = null;
                 }
 
-                if (gcInfo != null)
+                if (gcInfo != null && ((_options & ObjectWritingOptions.NoGcInfo) == 0))
                 {
                     EmitBlob(gcInfo);
                     gcInfo = null;
@@ -1327,5 +1327,6 @@ public enum ObjectWritingOptions
         GenerateDebugInfo = 0x01,
         ControlFlowGuard = 0x02,
         UseDwarf5 = 0x4,
+        NoGcInfo = 0x8,
     }
 }

src/coreclr/tools/aot/ILCompiler.RyuJit/Compiler/RyuJitCompilation.cs

@@ -100,6 +100,9 @@ protected override void CompileInternal(string outputFile, ObjectDumper dumper)
             if ((_compilationOptions & RyuJitCompilationOptions.ControlFlowGuardAnnotations) != 0)
                 options |= ObjectWritingOptions.ControlFlowGuard;
 
+            if ((_compilationOptions & RyuJitCompilationOptions.NoPreciseGc) != 0)
+                options |= ObjectWritingOptions.NoGcInfo;
+
             ObjectWriter.EmitObject(outputFile, nodes, NodeFactory, options, dumper, _logger);
         }
 
@@ -244,5 +247,6 @@ public enum RyuJitCompilationOptions
         ControlFlowGuardAnnotations = 0x2,
         UseDwarf5 = 0x4,
         UseResilience = 0x8,
+        NoPreciseGc = 0x10,
     }
 }

src/coreclr/tools/aot/ILCompiler.RyuJit/Compiler/RyuJitCompilationBuilder.cs

@@ -123,6 +123,9 @@ public override ICompilation ToCompilation()
             if (_resilient)
                 options |= RyuJitCompilationOptions.UseResilience;
 
+            if (!_isPreciseGc)
+                options |= RyuJitCompilationOptions.NoPreciseGc;
+
             var factory = new RyuJitNodeFactory(_context, _compilationGroup, _metadataManager, _interopStubManager, _nameMangler, _vtableSliceProvider, _dictionaryLayoutProvider, GetPreinitializationManager());
 
             JitConfigProvider.Initialize(_context.Target, jitFlagBuilder.ToArray(), _ryujitOptions, _jitPath);

src/coreclr/tools/aot/ILCompiler/Program.cs

@@ -62,6 +62,7 @@ internal sealed class Program
         private bool _completeTypesMetadata;
         private bool _scanReflection;
         private bool _methodBodyFolding;
+        private bool _noPreciseGc;
         private int _parallelism = Environment.ProcessorCount;
         private string _instructionSet;
         private string _guard;
@@ -221,6 +222,7 @@ private ArgumentSyntax ParseCommandLine(string[] args)
                 syntax.DefineOption("ildump", ref _ilDump, "Dump IL assembly listing for compiler-generated IL");
                 syntax.DefineOption("stacktracedata", ref _emitStackTraceData, "Emit data to support generating stack trace strings at runtime");
                 syntax.DefineOption("methodbodyfolding", ref _methodBodyFolding, "Fold identical method bodies");
+                syntax.DefineOption("noprecisegc", ref _noPreciseGc, "Do not generate precise stack GC information");
                 syntax.DefineOptionList("initassembly", ref _initAssemblies, "Assembly(ies) with a library initializer");
                 syntax.DefineOptionList("appcontextswitch", ref _appContextSwitches, "System.AppContext switches to set (format: 'Key=Value')");
                 syntax.DefineOptionList("feature", ref _featureSwitches, "Feature switches to apply (format: 'Namespace.Name=[true|false]'");
@@ -943,7 +945,8 @@ void RunScanner()
                 .UseOptimizationMode(_optimizationMode)
                 .UseSecurityMitigationOptions(securityMitigationOptions)
                 .UseDebugInfoProvider(debugInfoProvider)
-                .UseDwarf5(_useDwarf5);
+                .UseDwarf5(_useDwarf5)
+                .UseGCStackReporting(isPrecise: !_noPreciseGc);
 
             builder.UseResilience(_resilient);
 

src/tests/nativeaot/Directory.Build.props

@@ -0,0 +1,7 @@
+<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="..\Directory.Build.props" />
+
+  <PropertyGroup>
+    <IlcUseConservativeGc>true</IlcUseConservativeGc>
+  </PropertyGroup>
+</Project>