Enable sccache for linux-x64 coreclr PR builds

eng/pipelines/coreclr/templates/sccache-stats.yml

@@ -0,0 +1,18 @@
+parameters:
+  archType: 'x64'
+  osGroup: 'linux'
+  buildConfig: ''
+  runtimeFlavor: ''
+  runtimeVariant: ''
+  helixQueues: ''
+  targetRid: ''
+  nameSuffix: ''
+  platform: ''
+  shouldContinueOnError: false
+  osSubgroup: ''
+
+steps:
+  - ${{ if and(eq(parameters.osGroup, 'linux'), eq(parameters.osSubgroup, ''), eq(parameters.archType, 'x64')) }}:
+    - script: sccache --show-stats || true
+      displayName: Sccache stats
+      condition: always()

eng/pipelines/coreclr/templates/setup-sccache.yml

@@ -0,0 +1,40 @@
+parameters:
+  archType: 'x64'
+  osGroup: 'linux'
+  buildConfig: ''
+  runtimeFlavor: ''
+  runtimeVariant: ''
+  helixQueues: ''
+  targetRid: ''
+  nameSuffix: ''
+  platform: ''
+  shouldContinueOnError: false
+  osSubgroup: ''
+
+  # sccache NuGet package version — keep in sync with runtime-prereqs.proj
+  sccacheVersion: '0.15.0'
+
+steps:
+  - ${{ if and(eq(parameters.osGroup, 'linux'), eq(parameters.osSubgroup, ''), eq(parameters.archType, 'x64')) }}:
+    # Set up the Azure Pipeline Cache for sccache's local cache directory.
+    # Use a rolling key so each build can update the cache; restoreKeys
+    # falls back to the most recent saved entry.
+    - task: Cache@2
+      displayName: Sccache cache
+      inputs:
+        key: sccache | ${{ parameters.osGroup }} | ${{ parameters.archType }} | ${{ parameters.nameSuffix }} | ${{ parameters.buildConfig }} | "$(Build.BuildId)"
+        path: $(Pipeline.Workspace)/.sccache
+        restoreKeys: |
+          sccache | ${{ parameters.osGroup }} | ${{ parameters.archType }} | ${{ parameters.nameSuffix }} | ${{ parameters.buildConfig }}
+
+    # Configure sccache environment and add binary to PATH.
+    # The sccache package is restored by runtime-prereqs.proj during the build.
+    - script: |
+        sccacheVersion="${{ parameters.sccacheVersion }}"
+        sccacheDir="$(Build.SourcesDirectory)/.packages/sccache/${sccacheVersion}/tools"
+        mkdir -p "$sccacheDir"
+        echo "##vso[task.prependpath]$sccacheDir"
+        echo "##vso[task.setvariable variable=SCCACHE_DIR]$(Pipeline.Workspace)/.sccache"
+        echo "##vso[task.setvariable variable=SCCACHE_IDLE_TIMEOUT]0"
+        echo "##vso[task.setvariable variable=USE_SCCACHE]true"
+      displayName: Configure sccache

eng/pipelines/runtime.yml

@@ -254,7 +254,10 @@ extends:
             nameSuffix: CoreCLR_Libraries
             buildArgs: -s clr+libs+libs.tests -rc Release -c $(_BuildConfig) /p:ArchiveTests=true
             timeoutInMinutes: 120
+            preBuildSteps:
+              - template: /eng/pipelines/coreclr/templates/setup-sccache.yml
             postBuildSteps:
+              - template: /eng/pipelines/coreclr/templates/sccache-stats.yml
               - template: /eng/pipelines/common/upload-artifact-step.yml
                 parameters:
                   rootFolder: $(Build.SourcesDirectory)/artifacts/bin
@@ -399,7 +402,10 @@ extends:
             nameSuffix: Libraries_CheckedCoreCLR
             buildArgs: -s clr+clr.wasmjit+libs -c $(_BuildConfig) -rc Checked
             timeoutInMinutes: 120
+            preBuildSteps:
+              - template: /eng/pipelines/coreclr/templates/setup-sccache.yml
             postBuildSteps:
+              - template: /eng/pipelines/coreclr/templates/sccache-stats.yml
               - template: /eng/pipelines/coreclr/templates/build-native-test-assets-step.yml
               - template: /eng/pipelines/common/upload-artifact-step.yml
                 parameters:

src/coreclr/build-runtime.sh

@@ -174,6 +174,13 @@ if [[ "$__TargetArch" != "$__HostArch" ]]; then
 fi
 
 if [[ "$USE_SCCACHE" == "true" ]]; then
+    # NuGet strips execute permissions; restore them using the known package path.
+    # Try the CI-local packages dir first, then fall back to the global NuGet cache.
+    for sccacheBin in "$__RepoRootDir/.packages/sccache"/*/tools/sccache "$HOME/.nuget/packages/sccache"/*/tools/sccache; do
+        if [[ -f "$sccacheBin" ]]; then
+            chmod +x "$sccacheBin"
+        fi
+    done
     __CMakeArgs="-DCMAKE_C_COMPILER_LAUNCHER=sccache -DCMAKE_CXX_COMPILER_LAUNCHER=sccache $__CMakeArgs"
 fi
 

src/coreclr/runtime-prereqs.proj

@@ -10,6 +10,10 @@
     <AssemblyName>.NET Runtime</AssemblyName>
   </PropertyGroup>
 
+  <ItemGroup Condition="$([MSBuild]::IsOsPlatform(Linux)) and '$(ContinuousIntegrationBuild)' == 'true'">
+    <PackageDownload Include="sccache" Version="[0.15.0]" />
+  </ItemGroup>
+
   <Import Project="$(RepositoryEngineeringDir)versioning.targets" />
   <Import Project="$(RepositoryEngineeringDir)nativepgo.targets" />