From c294b47ff6713fb07dc913fba7bc33959c57e54e Mon Sep 17 00:00:00 2001
From: Marek Safar <marek.safar@gmail.com>
Date: Thu, 9 Jul 2020 17:58:31 +0200
Subject: [PATCH 1/6] Add always trimmed attributes list for browser config

Example of size reduction on SPC with the most minimalistic Hello
World sample.

| System.Private.CoreLib | Size (kB) | Delta |
|-|-|-|
| Original | 1358 kB | - |
| Trimmed | 1271 kB | - 87 kB |
---
 eng/illink.targets                            |  20 +--
 .../System.Private.CoreLib.csproj             |   3 +
 .../src/ILLink/ILLink.LinkAttributes.wasm.xml | 142 ++++++++++++++++++
 3 files changed, 156 insertions(+), 9 deletions(-)
 create mode 100644 src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml

diff --git a/eng/illink.targets b/eng/illink.targets
index fc38a10979f854..3cade70c8a2952 100644
--- a/eng/illink.targets
+++ b/eng/illink.targets
@@ -51,9 +51,9 @@
     <None Include="@(ILLinkSubstitutionsXmls)" />
   </ItemGroup>
 
-  <!-- Custom binplacing for pre/post-trimming and reports that is useful for analysis 
+  <!-- Custom binplacing for pre/post-trimming and reports that is useful for analysis
        Must be enabled by setting BinPlaceILLinkTrimAssembly=true
-  --> 
+  -->
   <ItemGroup Condition="'$(BinPlaceILLinkTrimAssembly)' == 'true'">
     <BinPlaceTargetFramework Include="$(BuildSettings)">
       <RuntimePath>$(ArtifactsBinDir)ILLinkTrimAssembly/$(BuildSettings)/trimmed</RuntimePath>
@@ -111,11 +111,11 @@
   <ItemGroup Condition="'$(GenerateResourcesSubstitutions)' == 'true'">
     <ILLinkSubstitutionsXmls Include="$(ILLinkResourcesSubstitutionIntermediatePath)" />
   </ItemGroup>
-  
+
   <!-- If a library uses string resources, the following target generates a substitution xml that will be embedded on the
   library so that if a consumer wants to run the linker they can specify a feature switch to strip out all resources
   from the assembly. -->
-  <Target Name="GenerateResourcesSubstitutionFile"  
+  <Target Name="GenerateResourcesSubstitutionFile"
           Condition="'$(GenerateResourcesSubstitutions)' == 'true'"
           Inputs="$(MSBuildProjectFullPath)"
           Outputs="$(ILLinkResourcesSubstitutionIntermediatePath)">
@@ -152,7 +152,7 @@
     </ItemGroup>
   </Target>
 
-  <Target Name="_SetILLinkTrimAssembly" 
+  <Target Name="_SetILLinkTrimAssembly"
           Condition="'$(ILLinkTrimAssembly)' == ''"
           DependsOnTargets="GetBinPlaceTargetFramework">
     <PropertyGroup>
@@ -186,6 +186,8 @@
       <ILLinkArgs Condition="'$(ILLinkTrimXmlLibraryBuild)' != ''">$(ILLinkArgs) -x "$(ILLinkTrimXmlLibraryBuild)"</ILLinkArgs>
       <!-- don't remove the embedded substitutions xml resource since ILLink may run again on the assembly -->
       <ILLinkArgs Condition="'$(ILLinkSubstitutionsXml)' != ''">$(ILLinkArgs) --strip-substitutions false</ILLinkArgs>
+      <!-- don't remove the embedded link attributes xml resource since ILLink may run again on the assembly -->
+      <ILLinkArgs Condition="'$(ILLinkLinkAttributes)' != ''">$(ILLinkArgs) --strip-link-attributes false</ILLinkArgs>
       <!-- ignore unresolved references -->
       <ILLinkArgs>$(ILLinkArgs) --skip-unresolved true</ILLinkArgs>
       <!-- keep interface implementations -->
@@ -235,7 +237,7 @@
       <_DotNetHostFileName>dotnet</_DotNetHostFileName>
       <_DotNetHostFileName Condition=" '$(OS)' == 'Windows_NT' ">dotnet.exe</_DotNetHostFileName>
     </PropertyGroup>
-    
+
     <ILLink AssemblyPaths="$(ILLinkTrimInputAssembly)"
             RootAssemblyNames=""
             OutputDirectory="$(ILLinkTrimOutputPath)"
@@ -272,10 +274,10 @@
     <Exec Command="$(AsmDiffCmd) $(AsmDiffListArgs)" />
     <Message Text="Assembly trimming report: $(AsmDiffList)" />
   </Target>
-  
-  <!-- Similar to _CheckForCompileOutputs and runs in the same places, 
+
+  <!-- Similar to _CheckForCompileOutputs and runs in the same places,
        always set these even if compile didn't run. -->
-  <Target Name="_CheckForILLinkTrimAssemblyOutputs" 
+  <Target Name="_CheckForILLinkTrimAssemblyOutputs"
           BeforeTargets="CopyFilesToOutputDirectory;_CleanGetCurrentAndPriorFileWrites"
           Condition="'$(ILLinkTrimAssembly)' == 'true'">
     <ItemGroup>
diff --git a/src/mono/netcore/System.Private.CoreLib/System.Private.CoreLib.csproj b/src/mono/netcore/System.Private.CoreLib/System.Private.CoreLib.csproj
index 2eb2ec324e1f13..5cdb8f1698da9e 100644
--- a/src/mono/netcore/System.Private.CoreLib/System.Private.CoreLib.csproj
+++ b/src/mono/netcore/System.Private.CoreLib/System.Private.CoreLib.csproj
@@ -152,6 +152,9 @@
 
     <ILLinkSubstitutionsXmls Include="$(ILLinkDirectory)ILLink.Substitutions.$(Platform).xml"
                              Condition="Exists('$(ILLinkDirectory)ILLink.Substitutions.$(Platform).xml')" />
+
+    <ILLinkLinkAttributes Include="$(ILLinkDirectory)/ILLink.LinkAttributes.$(Platform).xml"
+                             Condition="Exists('$(ILLinkDirectory)ILLink.LinkAttributes.$(Platform).xml')" />
   </ItemGroup>
 
   <!-- Sources -->
diff --git a/src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml b/src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml
new file mode 100644
index 00000000000000..c613fdf807f9a0
--- /dev/null
+++ b/src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml
@@ -0,0 +1,142 @@
+<linker>
+  <assembly fullname="*">
+    <!-- System -->
+    <type fullname="System.CLSCompliantAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.ObsoleteAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.ParamArrayAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+
+    <!-- System.Diagnostics.CodeAnalysis -->
+    <type fullname="System.Diagnostics.CodeAnalysis.DynamicallyAccessedMembersAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Diagnostics.CodeAnalysis.SuppressMessageAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Diagnostics.CodeAnalysis.RequiresUnreferencedCodeAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Diagnostics.CodeAnalysis.AllowNullAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Diagnostics.CodeAnalysis.DisallowNullAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Diagnostics.CodeAnalysis.MaybeNullAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Diagnostics.CodeAnalysis.MaybeNullWhenAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Diagnostics.CodeAnalysis.NotNullAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Diagnostics.CodeAnalysis.NotNullWhenAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Diagnostics.CodeAnalysis.DoesNotReturnAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Diagnostics.CodeAnalysis.DoesNotReturnIfAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Diagnostics.CodeAnalysis.MemberNotNullAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Diagnostics.CodeAnalysis.MemberNotNullWhenAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Diagnostics.CodeAnalysis.MemberNotNullWhenAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+
+    <!-- System.Runtime.CompilerServices -->
+    <type fullname="System.Runtime.CompilerServices.AsyncMethodBuilderAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Runtime.CompilerServices.CallerArgumentExpressionAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Runtime.CompilerServices.CallerMemberNameAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Runtime.CompilerServices.CallerFilePathAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Runtime.CompilerServices.CallerLineNumberAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Runtime.CompilerServices.CallerMemberNameAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Runtime.CompilerServices.CompilerGlobalScopeAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Runtime.CompilerServices.CompilerGeneratedAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Runtime.CompilerServices.DynamicAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Runtime.CompilerServices.EnumeratorCancellationAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Runtime.CompilerServices.ExtensionAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Runtime.CompilerServices.IntrinsicAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Runtime.CompilerServices.IsReadOnlyAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Runtime.CompilerServices.IsUnmanagedAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Runtime.CompilerServices.NativeIntegerAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Runtime.CompilerServices.NullableAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Runtime.CompilerServices.NullableContextAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Runtime.CompilerServices.NullablePublicOnlyAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Runtime.CompilerServices.SkipLocalsInitAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+    <type fullname="System.Runtime.CompilerServices.TupleElementNamesAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+
+    <!-- System.Runtime.Versioning -->
+    <type fullname="System.Runtime.Versioning.NonVersionableAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+
+    <!-- Microsoft.CodeAnalysis -->
+    <type fullname="Microsoft.CodeAnalysis.EmbeddedAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+
+    <!-- Microsoft.ComponentModel -->
+    <type fullname="System.ComponentModel.EditorBrowsableAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
+
+  </assembly>
+</linker>

From 08d790a3ba608168dfff3d1a15a522545b9cb7da Mon Sep 17 00:00:00 2001
From: Marek Safar <marek.safar@gmail.com>
Date: Thu, 9 Jul 2020 19:01:10 +0200
Subject: [PATCH 2/6] Review feedback

---
 .../src/ILLink/ILLink.LinkAttributes.wasm.xml            | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml b/src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml
index c613fdf807f9a0..02f4c5e27929cb 100644
--- a/src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml
+++ b/src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml
@@ -7,9 +7,6 @@
     <type fullname="System.ObsoleteAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
-    <type fullname="System.ParamArrayAttribute">
-      <attribute internal="RemoveAttributeInstances" />
-    </type>
 
     <!-- System.Diagnostics.CodeAnalysis -->
     <type fullname="System.Diagnostics.CodeAnalysis.DynamicallyAccessedMembersAttribute">
@@ -57,9 +54,6 @@
     <type fullname="System.Diagnostics.CodeAnalysis.MemberNotNullWhenAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
-    <type fullname="System.Diagnostics.CodeAnalysis.MemberNotNullWhenAttribute">
-      <attribute internal="RemoveAttributeInstances" />
-    </type>
 
     <!-- System.Runtime.CompilerServices -->
     <type fullname="System.Runtime.CompilerServices.AsyncMethodBuilderAttribute">
@@ -86,9 +80,6 @@
     <type fullname="System.Runtime.CompilerServices.CompilerGeneratedAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
-    <type fullname="System.Runtime.CompilerServices.DynamicAttribute">
-      <attribute internal="RemoveAttributeInstances" />
-    </type>
     <type fullname="System.Runtime.CompilerServices.EnumeratorCancellationAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>

From ffe0b6d9e1148ce2da25d480ac3103d1872233f0 Mon Sep 17 00:00:00 2001
From: Eric Erhardt <eric.erhardt@microsoft.com>
Date: Thu, 9 Jul 2020 14:01:46 -0500
Subject: [PATCH 3/6] Combine and embed the ILLink.LinkAttributes.xml file into
 the assembly.

---
 eng/illink.targets                            | 27 +++++++++++++++++--
 .../System.Private.CoreLib.csproj             |  4 +--
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/eng/illink.targets b/eng/illink.targets
index 3cade70c8a2952..7ceaa32557897f 100644
--- a/eng/illink.targets
+++ b/eng/illink.targets
@@ -41,6 +41,7 @@
     <ILLinkDescriptorsXmlIntermediatePath>$(IntermediateOutputPath)ILLink.Descriptors.xml</ILLinkDescriptorsXmlIntermediatePath>
 
     <ILLinkSubstitutionsXmlIntermediatePath>$(IntermediateOutputPath)ILLink.Substitutions.xml</ILLinkSubstitutionsXmlIntermediatePath>
+    <ILLinkLinkAttributesXmlIntermediatePath>$(IntermediateOutputPath)ILLink.LinkAttributes.xml</ILLinkLinkAttributesXmlIntermediatePath>
 
     <!-- if building a PDB, tell illink to rewrite the symbols file -->
     <ILLinkRewritePDBs Condition="'$(ILLinkRewritePDBs)' == '' and '$(DebugSymbols)' != 'false'">true</ILLinkRewritePDBs>
@@ -70,7 +71,7 @@
   </ItemGroup>
 
   <Target Name="_EmbedILLinkXmls"
-          DependsOnTargets="_CombineILLinkDescriptorsXmls;_CombineILLinkSubstitutionsXmls">
+          DependsOnTargets="_CombineILLinkDescriptorsXmls;_CombineILLinkSubstitutionsXmls;_CombineILLinkLinkAttributesXmls">
 
     <ItemGroup Condition="'$(ILLinkTrimXml)' != ''">
       <EmbeddedResource Include="$(ILLinkTrimXml)">
@@ -84,6 +85,12 @@
       </EmbeddedResource>
     </ItemGroup>
 
+    <ItemGroup Condition="'$(ILLinkLinkAttributesXml)' != ''">
+      <EmbeddedResource Include="$(ILLinkLinkAttributesXml)">
+        <LogicalName>ILLink.LinkAttributes.xml</LogicalName>
+      </EmbeddedResource>
+    </ItemGroup>
+
   </Target>
 
   <UsingTask TaskName="CombineLinkerXmlFiles" AssemblyFile="$(ILLinkTasksPath)" />
@@ -152,6 +159,22 @@
     </ItemGroup>
   </Target>
 
+  <Target Name="_CombineILLinkLinkAttributesXmls"
+          Condition="'@(ILLinkLinkAttributesXmls)' != ''"
+          Inputs="@(ILLinkLinkAttributesXmls)"
+          Outputs="$(ILLinkLinkAttributesXmlIntermediatePath)">
+    <PropertyGroup>
+      <ILLinkLinkAttributesXml>$(ILLinkLinkAttributesXmlIntermediatePath)</ILLinkLinkAttributesXml>
+    </PropertyGroup>
+
+    <CombineLinkerXmlFiles LinkerXmlFiles="@(ILLinkLinkAttributesXmls)"
+                           CombinedLinkerXmlFile="$(ILLinkLinkAttributesXml)" />
+
+    <ItemGroup>
+      <FileWrites Include="$(ILLinkLinkAttributesXml)" />
+    </ItemGroup>
+  </Target>
+
   <Target Name="_SetILLinkTrimAssembly"
           Condition="'$(ILLinkTrimAssembly)' == ''"
           DependsOnTargets="GetBinPlaceTargetFramework">
@@ -187,7 +210,7 @@
       <!-- don't remove the embedded substitutions xml resource since ILLink may run again on the assembly -->
       <ILLinkArgs Condition="'$(ILLinkSubstitutionsXml)' != ''">$(ILLinkArgs) --strip-substitutions false</ILLinkArgs>
       <!-- don't remove the embedded link attributes xml resource since ILLink may run again on the assembly -->
-      <ILLinkArgs Condition="'$(ILLinkLinkAttributes)' != ''">$(ILLinkArgs) --strip-link-attributes false</ILLinkArgs>
+      <ILLinkArgs Condition="'$(ILLinkLinkAttributesXml)' != ''">$(ILLinkArgs) --strip-link-attributes false</ILLinkArgs>
       <!-- ignore unresolved references -->
       <ILLinkArgs>$(ILLinkArgs) --skip-unresolved true</ILLinkArgs>
       <!-- keep interface implementations -->
diff --git a/src/mono/netcore/System.Private.CoreLib/System.Private.CoreLib.csproj b/src/mono/netcore/System.Private.CoreLib/System.Private.CoreLib.csproj
index 5cdb8f1698da9e..8b2acf2ac74f45 100644
--- a/src/mono/netcore/System.Private.CoreLib/System.Private.CoreLib.csproj
+++ b/src/mono/netcore/System.Private.CoreLib/System.Private.CoreLib.csproj
@@ -153,8 +153,8 @@
     <ILLinkSubstitutionsXmls Include="$(ILLinkDirectory)ILLink.Substitutions.$(Platform).xml"
                              Condition="Exists('$(ILLinkDirectory)ILLink.Substitutions.$(Platform).xml')" />
 
-    <ILLinkLinkAttributes Include="$(ILLinkDirectory)/ILLink.LinkAttributes.$(Platform).xml"
-                             Condition="Exists('$(ILLinkDirectory)ILLink.LinkAttributes.$(Platform).xml')" />
+    <ILLinkLinkAttributesXmls Include="$(ILLinkDirectory)/ILLink.LinkAttributes.$(Platform).xml"
+                              Condition="Exists('$(ILLinkDirectory)ILLink.LinkAttributes.$(Platform).xml')" />
   </ItemGroup>
 
   <!-- Sources -->

From bb840d2cade56829c2e79ff2de2198989a81246a Mon Sep 17 00:00:00 2001
From: Eric Erhardt <eric.erhardt@microsoft.com>
Date: Thu, 9 Jul 2020 16:07:16 -0500
Subject: [PATCH 4/6] Update linker command line to ignore attributes file. Add
 ExcludeFromCodeCoverageAttribute.

---
 eng/illink.targets                                             | 3 ++-
 .../src/ILLink/ILLink.LinkAttributes.wasm.xml                  | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/eng/illink.targets b/eng/illink.targets
index 7ceaa32557897f..7914b6cfaba832 100644
--- a/eng/illink.targets
+++ b/eng/illink.targets
@@ -210,7 +210,8 @@
       <!-- don't remove the embedded substitutions xml resource since ILLink may run again on the assembly -->
       <ILLinkArgs Condition="'$(ILLinkSubstitutionsXml)' != ''">$(ILLinkArgs) --strip-substitutions false</ILLinkArgs>
       <!-- don't remove the embedded link attributes xml resource since ILLink may run again on the assembly -->
-      <ILLinkArgs Condition="'$(ILLinkLinkAttributesXml)' != ''">$(ILLinkArgs) --strip-link-attributes false</ILLinkArgs>
+      <!-- and ignore the link attributes xml file during the library build, since we need the attributes preserved until the final app is linked -->
+      <ILLinkArgs Condition="'$(ILLinkLinkAttributesXml)' != ''">$(ILLinkArgs) --strip-link-attributes false --ignore-link-attributes true</ILLinkArgs>
       <!-- ignore unresolved references -->
       <ILLinkArgs>$(ILLinkArgs) --skip-unresolved true</ILLinkArgs>
       <!-- keep interface implementations -->
diff --git a/src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml b/src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml
index 02f4c5e27929cb..f35d26667dbc3b 100644
--- a/src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml
+++ b/src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml
@@ -12,6 +12,9 @@
     <type fullname="System.Diagnostics.CodeAnalysis.DynamicallyAccessedMembersAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
+    <type fullname="System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverageAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
     <type fullname="System.Diagnostics.CodeAnalysis.SuppressMessageAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>

From 64f2a4589bfb165d8a69709d64b659831b055337 Mon Sep 17 00:00:00 2001
From: Eric Erhardt <eric.erhardt@microsoft.com>
Date: Thu, 9 Jul 2020 17:43:03 -0500
Subject: [PATCH 5/6] PR feedback. Add note about Obsolete. Only use assembly
 fullname="*" for compiler generated attributes.

---
 .../src/ILLink/ILLink.LinkAttributes.wasm.xml | 48 +++++++++++--------
 1 file changed, 29 insertions(+), 19 deletions(-)

diff --git a/src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml b/src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml
index f35d26667dbc3b..3e150d1a6381b3 100644
--- a/src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml
+++ b/src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml
@@ -1,10 +1,16 @@
 <linker>
-  <assembly fullname="*">
+  <assembly fullname="System.Private.CoreLib">
     <!-- System -->
     <type fullname="System.CLSCompliantAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
     <type fullname="System.ObsoleteAttribute">
+      <!--
+        Note that removing this attribute can change runtime behavior. For example,
+        System.Xml.Serialization will behave differently if a ctor is Obsolete.
+        This is low enough risk on wasm to justify the removing the attribute for size
+        savings. The app developer can override this setting to keep all ObsoleteAttributes.
+        -->
       <attribute internal="RemoveAttributeInstances" />
     </type>
 
@@ -77,10 +83,13 @@
     <type fullname="System.Runtime.CompilerServices.CallerMemberNameAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
+    <type fullname="System.Runtime.CompilerServices.CompilerGeneratedAttribute">
+      <attribute internal="RemoveAttributeInstances" />
+    </type>
     <type fullname="System.Runtime.CompilerServices.CompilerGlobalScopeAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
-    <type fullname="System.Runtime.CompilerServices.CompilerGeneratedAttribute">
+    <type fullname="System.Runtime.CompilerServices.IsReadOnlyAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
     <type fullname="System.Runtime.CompilerServices.EnumeratorCancellationAttribute">
@@ -92,33 +101,40 @@
     <type fullname="System.Runtime.CompilerServices.IntrinsicAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
-    <type fullname="System.Runtime.CompilerServices.IsReadOnlyAttribute">
+    <type fullname="System.Runtime.CompilerServices.SkipLocalsInitAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
-    <type fullname="System.Runtime.CompilerServices.IsUnmanagedAttribute">
+    <type fullname="System.Runtime.CompilerServices.TupleElementNamesAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
-    <type fullname="System.Runtime.CompilerServices.NativeIntegerAttribute">
+
+    <!-- System.Runtime.Versioning -->
+    <type fullname="System.Runtime.Versioning.NonVersionableAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
-    <type fullname="System.Runtime.CompilerServices.NullableAttribute">
+
+    <!-- Microsoft.ComponentModel -->
+    <type fullname="System.ComponentModel.EditorBrowsableAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
-    <type fullname="System.Runtime.CompilerServices.NullableContextAttribute">
+  </assembly>
+
+  <!-- The following attributes are generated by the compiler, so they could be in any assembly -->
+  <assembly fullname="*">
+    <!-- System.Runtime.CompilerServices -->
+    <type fullname="System.Runtime.CompilerServices.IsUnmanagedAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
-    <type fullname="System.Runtime.CompilerServices.NullablePublicOnlyAttribute">
+    <type fullname="System.Runtime.CompilerServices.NativeIntegerAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
-    <type fullname="System.Runtime.CompilerServices.SkipLocalsInitAttribute">
+    <type fullname="System.Runtime.CompilerServices.NullableAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
-    <type fullname="System.Runtime.CompilerServices.TupleElementNamesAttribute">
+    <type fullname="System.Runtime.CompilerServices.NullableContextAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
-
-    <!-- System.Runtime.Versioning -->
-    <type fullname="System.Runtime.Versioning.NonVersionableAttribute">
+    <type fullname="System.Runtime.CompilerServices.NullablePublicOnlyAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
 
@@ -126,11 +142,5 @@
     <type fullname="Microsoft.CodeAnalysis.EmbeddedAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
-
-    <!-- Microsoft.ComponentModel -->
-    <type fullname="System.ComponentModel.EditorBrowsableAttribute">
-      <attribute internal="RemoveAttributeInstances" />
-    </type>
-
   </assembly>
 </linker>

From fc69953d98e61b8d758c44c6a6451de7f1734351 Mon Sep 17 00:00:00 2001
From: Marek Safar <marek.safar@gmail.com>
Date: Fri, 10 Jul 2020 09:10:31 +0200
Subject: [PATCH 6/6] Update ILLink.LinkAttributes.wasm.xml

---
 .../src/ILLink/ILLink.LinkAttributes.wasm.xml                | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml b/src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml
index 3e150d1a6381b3..78fc3756bf0e41 100644
--- a/src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml
+++ b/src/mono/netcore/System.Private.CoreLib/src/ILLink/ILLink.LinkAttributes.wasm.xml
@@ -83,7 +83,10 @@
     <type fullname="System.Runtime.CompilerServices.CallerMemberNameAttribute">
       <attribute internal="RemoveAttributeInstances" />
     </type>
-    <type fullname="System.Runtime.CompilerServices.CompilerGeneratedAttribute">
+    <type fullname="System.Runtime.CompilerServices.CompilerGeneratedAttribute" feature="System.Diagnostics.Debugger.IsSupported" featurevalue="false">
+      <!--
+        The attribute is used during pretty stack trace printing
+        -->          
       <attribute internal="RemoveAttributeInstances" />
     </type>
     <type fullname="System.Runtime.CompilerServices.CompilerGlobalScopeAttribute">