From a2ab6834f008581a9708c17b40ceb9fd29189ed7 Mon Sep 17 00:00:00 2001
From: Sven Boemer <sbomer@gmail.com>
Date: Thu, 27 Apr 2023 18:22:06 +0000
Subject: [PATCH 1/3] Prefer lld in NativeAot when using clang

This detects availability of lld and prefers it, when
using clang. If not found, falls back on bfd as before.
---
 .../Microsoft.NETCore.Native.Unix.targets          | 14 +++++++++++---
 .../Microsoft.NETCore.Native.targets               |  4 ++--
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Unix.targets b/src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Unix.targets
index bb457c8c166bc..71d9b1ef51bb9 100644
--- a/src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Unix.targets
+++ b/src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Unix.targets
@@ -22,7 +22,6 @@ The .NET Foundation licenses this file to you under the MIT license.
     <DsymUtilOptions Condition="'$(_IsApplePlatform)' == 'true'">--flat</DsymUtilOptions>
     <_SymbolPrefix Condition="'$(_IsApplePlatform)' == 'true'">_</_SymbolPrefix>
     <LinkerFlavor Condition="'$(LinkerFlavor)' == '' and '$(_targetOS)' == 'freebsd'">lld</LinkerFlavor>
-    <LinkerFlavor Condition="'$(LinkerFlavor)' == '' and '$(_targetOS)' == 'linux'">bfd</LinkerFlavor>
   </PropertyGroup>
 
   <Target Name="SetupOSSpecificProps" DependsOnTargets="$(IlcDynamicBuildPropertyDependencies)">
@@ -104,7 +103,6 @@ The .NET Foundation licenses this file to you under the MIT license.
     </ItemGroup>
 
     <ItemGroup>
-      <LinkerArg Include="-fuse-ld=$(LinkerFlavor)" Condition="'$(LinkerFlavor)' != ''" />
       <LinkerArg Include="@(NativeLibrary)" />
       <LinkerArg Include="--sysroot=$(SysRoot)" Condition="'$(SysRoot)' != ''" />
       <LinkerArg Include="--target=$(TargetTriple)" Condition="'$(_IsApplePlatform)' != 'true' and '$(TargetTriple)' != ''" />
@@ -180,11 +178,21 @@ The .NET Foundation licenses this file to you under the MIT license.
     <Error Condition="'$(_WhereLinker)' != '0' and '$(CppCompilerAndLinkerAlternative)' == '' and '$(_IsApplePlatform)' != 'true'"
       Text="Requested linker ('$(CppLinker)') not found in PATH." />
 
-    <Exec Command="&quot;$(CppLinker)&quot; -fuse-ld=lld -Wl,--version" Condition="'$(LinkerFlavor)' == 'lld'" IgnoreExitCode="true" StandardOutputImportance="Low" ConsoleToMSBuild="true">
+    <Exec Command="&quot;$(CppLinker)&quot; -fuse-ld=lld -Wl,--version" Condition="'$(LinkerFlavor)' == 'lld' or ('$(LinkerFlavor)' == '' and '$(CppLinker)' == 'clang')"
+          IgnoreExitCode="true" IgnoreStandardErrorWarningFormat="true" StandardOutputImportance="Low" StandardErrorImportance="Low" ConsoleToMSBuild="true">
       <Output TaskParameter="ExitCode" PropertyName="_LinkerVersionStringExitCode" />
       <Output TaskParameter="ConsoleOutput" PropertyName="_LinkerVersionString" />
     </Exec>
 
+    <PropertyGroup Condition="'$(LinkerFlavor)' == ''">
+      <LinkerFlavor Condition="'$(_LinkerVersionStringExitCode)' == '0'">lld</LinkerFlavor>
+      <LinkerFlavor Condition="'$(LinkerFlavor)' == '' and '$(_targetOS)' == 'linux'">bfd</LinkerFlavor>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <LinkerArg Include="-fuse-ld=$(LinkerFlavor)" Condition="'$(LinkerFlavor)' != ''" />
+    </ItemGroup>
+
     <PropertyGroup Condition="'$(_LinkerVersionStringExitCode)' == '0' and '$(_LinkerVersionString)' != ''">
       <_LinkerVersion>$([System.Text.RegularExpressions.Regex]::Match($(_LinkerVersionString), '[1-9]\d*'))</_LinkerVersion>
     </PropertyGroup>
diff --git a/src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.targets b/src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.targets
index 2ead5803e5cea..0d5451a5b1f1f 100644
--- a/src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.targets
+++ b/src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.targets
@@ -321,7 +321,7 @@ The .NET Foundation licenses this file to you under the MIT license.
     <ItemGroup Condition="'$(_targetOS)' != 'win' and '$(_IsApplePlatform)' != 'true'">
       <CustomLinkerArg Include="-Wl,--discard-all" />
       <CustomLinkerArg Include="-Wl,--gc-sections" Condition="'$(LinkerFlavor)' == '' or '$(LinkerFlavor)' == 'bfd' or '$(LinkerFlavor)' == 'lld'" />
-      <CustomLinkerArg Include="-Wl,-T,&quot;$(NativeIntermediateOutputPath)sections.ld&quot;" Condition="'$(LinkerFlavor)' == 'lld' and '$(_LinkerVersion)' &gt; '12'" />
+      <CustomLinkerArg Include="-Wl,-T,&quot;$(NativeIntermediateOutputPath)sections.ld&quot;" Condition="'$(LinkerFlavor)' == 'lld' and '$(_LinkerVersion)' != '' and '$(_LinkerVersion)' &gt; '12'" />
     </ItemGroup>
     <ItemGroup>
       <CustomLibArg Include="-crs &quot;$(NativeBinary)&quot;" Condition="'$(_targetOS)' != 'win'" />
@@ -340,7 +340,7 @@ The .NET Foundation licenses this file to you under the MIT license.
     </PropertyGroup>
 
     <!-- write linker script for lld (13+) to retain the __modules section -->
-    <WriteLinesToFile File="$(NativeIntermediateOutputPath)sections.ld" Lines="OVERWRITE_SECTIONS { __modules : { KEEP(*(__modules)) } }" Overwrite="true" Condition="'$(LinkerFlavor)' == 'lld' and '$(_LinkerVersion)' &gt; '12'" />
+    <WriteLinesToFile File="$(NativeIntermediateOutputPath)sections.ld" Lines="OVERWRITE_SECTIONS { __modules : { KEEP(*(__modules)) } }" Overwrite="true" Condition="'$(LinkerFlavor)' == 'lld' and '$(_LinkerVersion)' != '' and '$(_LinkerVersion)' &gt; '12'" />
 
     <Exec Command="&quot;$(CppLinker)&quot; @(CustomLinkerArg, ' ')" Condition="'$(_targetOS)' != 'win' and '$(NativeLib)' != 'Static'" IgnoreStandardErrorWarningFormat="$(_IgnoreLinkerWarnings)" />
     <Exec Command="&quot;$(CppLibCreator)&quot; @(CustomLibArg, ' ')" Condition="'$(_targetOS)' != 'win' and '$(NativeLib)' == 'Static'" />

From a1d7be84c1f9f6acb3ffc95938bd8f28ddc47cc2 Mon Sep 17 00:00:00 2001
From: Sven Boemer <sbomer@gmail.com>
Date: Thu, 27 Apr 2023 18:30:29 +0000
Subject: [PATCH 2/3] Remove LinkerFlavor settings from runtime build

---
 eng/testing/tests.singlefile.targets             | 1 -
 src/coreclr/tools/aot/crossgen2/crossgen2.csproj | 5 -----
 src/tests/Directory.Build.targets                | 1 -
 3 files changed, 7 deletions(-)

diff --git a/eng/testing/tests.singlefile.targets b/eng/testing/tests.singlefile.targets
index 5fb0e1bd643ea..232114834721a 100644
--- a/eng/testing/tests.singlefile.targets
+++ b/eng/testing/tests.singlefile.targets
@@ -29,7 +29,6 @@
     <IlcSdkPath>$(CoreCLRAotSdkDir)</IlcSdkPath>
     <IlcFrameworkPath>$(NetCoreAppCurrentTestHostSharedFrameworkPath)</IlcFrameworkPath>
     <IlcFrameworkNativePath>$(NetCoreAppCurrentTestHostSharedFrameworkPath)</IlcFrameworkNativePath>
-    <LinkerFlavor Condition="'$(TargetOS)' == 'linux'">lld</LinkerFlavor>
     <NoWarn>$(NoWarn);IL1005;IL2105;IL3000;IL3001;IL3002;IL3003</NoWarn>
     <TrimMode>partial</TrimMode>
     <SuppressTrimAnalysisWarnings>true</SuppressTrimAnalysisWarnings>
diff --git a/src/coreclr/tools/aot/crossgen2/crossgen2.csproj b/src/coreclr/tools/aot/crossgen2/crossgen2.csproj
index e19cbbeae9f6e..a18ff70964a1d 100644
--- a/src/coreclr/tools/aot/crossgen2/crossgen2.csproj
+++ b/src/coreclr/tools/aot/crossgen2/crossgen2.csproj
@@ -88,11 +88,6 @@
   <Target Name="LocateNativeCompiler"
           Condition="'$(NativeAotSupported)' == 'true' and '$(_IsPublishing)' == 'true' and '$(HostOS)' != 'windows'"
           BeforeTargets="SetupOSSpecificProps">
-      <PropertyGroup>
-        <CppCompilerAndLinker Condition="'$(CppCompilerAndLinker)' == ''">clang</CppCompilerAndLinker>
-        <LinkerFlavor Condition="'$(CppCompilerAndLinker)' == 'clang' and '$(TargetOS)' == 'linux'">lld</LinkerFlavor>
-      </PropertyGroup>
-
       <Exec Command="sh -c 'build_arch=&quot;$(TargetArchitecture)&quot; compiler=&quot;$(CppCompilerAndLinker)&quot; . &quot;$(RepositoryEngineeringDir)/common/native/init-compiler.sh&quot; &amp;&amp; echo $CC' 2>/dev/null"
             EchoOff="true"
             ConsoleToMsBuild="true"
diff --git a/src/tests/Directory.Build.targets b/src/tests/Directory.Build.targets
index 6f6fc552ba222..b4989daad8d5d 100644
--- a/src/tests/Directory.Build.targets
+++ b/src/tests/Directory.Build.targets
@@ -533,7 +533,6 @@
     <IlcFrameworkNativePath>$(MicrosoftNetCoreAppRuntimePackNativeDir)</IlcFrameworkNativePath>
     <RuntimeIdentifier>$(OutputRID)</RuntimeIdentifier>
 
-    <LinkerFlavor Condition="'$(TargetOS)' == 'linux'">lld</LinkerFlavor>
     <SysRoot Condition="'$(CrossBuild)' == 'true' and '$(HostOS)' != 'windows'">$(ROOTFS_DIR)</SysRoot>
     <BuildNativeAotFrameworkObjects Condition="'$(IlcMultiModule)' == 'true'">true</BuildNativeAotFrameworkObjects>
     <DisableFrameworkLibGeneration Condition="'$(BuildNativeAotFrameworkObjects)' == 'true'">true</DisableFrameworkLibGeneration>

From c21d315b11b69423903cf13f04068cb93b14ad39 Mon Sep 17 00:00:00 2001
From: Sven Boemer <sbomer@gmail.com>
Date: Fri, 28 Apr 2023 15:46:17 +0000
Subject: [PATCH 3/3] Fix logic to work with overridden CppLinker

Also use CppCompilerAndLinker to match existing pattern
---
 .../BuildIntegration/Microsoft.NETCore.Native.Unix.targets      | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Unix.targets b/src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Unix.targets
index 71d9b1ef51bb9..558a37784fb11 100644
--- a/src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Unix.targets
+++ b/src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Unix.targets
@@ -178,7 +178,7 @@ The .NET Foundation licenses this file to you under the MIT license.
     <Error Condition="'$(_WhereLinker)' != '0' and '$(CppCompilerAndLinkerAlternative)' == '' and '$(_IsApplePlatform)' != 'true'"
       Text="Requested linker ('$(CppLinker)') not found in PATH." />
 
-    <Exec Command="&quot;$(CppLinker)&quot; -fuse-ld=lld -Wl,--version" Condition="'$(LinkerFlavor)' == 'lld' or ('$(LinkerFlavor)' == '' and '$(CppLinker)' == 'clang')"
+    <Exec Command="&quot;$(CppLinker)&quot; -fuse-ld=lld -Wl,--version" Condition="'$(LinkerFlavor)' == 'lld' or ('$(LinkerFlavor)' == '' and $(CppCompilerAndLinker.Contains('clang')))"
           IgnoreExitCode="true" IgnoreStandardErrorWarningFormat="true" StandardOutputImportance="Low" StandardErrorImportance="Low" ConsoleToMSBuild="true">
       <Output TaskParameter="ExitCode" PropertyName="_LinkerVersionStringExitCode" />
       <Output TaskParameter="ConsoleOutput" PropertyName="_LinkerVersionString" />