Implement user experience for LIPO / ThinLTO users.

Add flag --convert_lipo_to_thinlto, which allows builds with LLVM to use
ThinLTO when the user specifies LIPO + FDO flags; if that flag is not set, and
the user requests a build with LLVM, the compile will now fail.

Add an attribute supports_lipo to the DefaultCpuToolchain crosstool proto and
skip default toolchains that do not support LIPO when the user has specified
LIPO flags in the toolchain selection; this enables CROSSTOOL files to cause
an implicit fallback to a hybrid / LIPO toolchain when using an LLVM toolchain
as the default.

Add a CrosstoolBuilder to MockCcSupport and add a new method
setupCrosstoolFromScratch that allows unit tests to fully control the setup.
The other methods available in MockCcSupport will always load in a default
CROSSTOOL file and may show different unit test results depending on the
content of that file.

RELNOTES: None.
PiperOrigin-RevId: 163819246

1 files changed, 95 insertions, 0 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/packages/util/MockCcSupport.java b/src/test/java/com/google/devtools/build/lib/packages/util/MockCcSupport.java
index fae4347df9..f3e368a7bd 100644
--- a/src/test/java/com/google/devtools/build/lib/packages/util/MockCcSupport.java
+++ b/src/test/java/com/google/devtools/build/lib/packages/util/MockCcSupport.java
@@ -36,6 +36,76 @@ import java.io.IOException;
  */
 public abstract class MockCcSupport {
 
+  /**
+   * Builder to build crosstool files for unit testing.
+   */
+  public static final class CrosstoolBuilder {
+    public static final String DEFAULT_TARGET_CPU = "k8";
+    public static final String MAJOR_VERSION = "13";
+    public static final String MINOR_VERSION = "0";
+
+    private final CrosstoolConfig.CrosstoolRelease.Builder builder =
+        CrosstoolConfig.CrosstoolRelease.newBuilder()
+            .setMajorVersion(MAJOR_VERSION)
+            .setMinorVersion(MINOR_VERSION)
+            .setDefaultTargetCpu(DEFAULT_TARGET_CPU);
+
+    /** Adds a default toolchain in the order of the calls. */
+    public CrosstoolBuilder addDefaultToolchain(String cpu, String toolchainIdentifier) {
+      builder.addDefaultToolchainBuilder().setCpu(cpu).setToolchainIdentifier(toolchainIdentifier);
+      return this;
+    }
+
+    /** Adds a default toolchain in the order of the calls. */
+    public CrosstoolBuilder addDefaultToolchain(
+        String cpu, String toolchainIdentifier, boolean supportsLipo) {
+      builder
+          .addDefaultToolchainBuilder()
+          .setCpu(cpu)
+          .setToolchainIdentifier(toolchainIdentifier)
+          .setSupportsLipo(supportsLipo);
+      return this;
+    }
+
+    /** Adds a toolchain where all required fields are set. */
+    public CrosstoolBuilder addToolchain(String cpu, String toolchainIdentifier, String compiler) {
+      builder
+          .addToolchainBuilder()
+          .setTargetCpu(cpu)
+          .setToolchainIdentifier(toolchainIdentifier)
+          .setHostSystemName("host-system-name")
+          .setTargetSystemName("target-system-name")
+          .setTargetLibc("target-libc")
+          .setCompiler(compiler)
+          .setAbiVersion("abi-version")
+          .setAbiLibcVersion("abi-libc-version")
+          // TODO(klimek): Move to features.
+          .setSupportsStartEndLib(true);
+      return this;
+    }
+
+    /** Appends the snippet {@code configuration} to all previously added toolchains. */
+    public CrosstoolBuilder appendToAllToolchains(CToolchain configuration) {
+      for (CToolchain.Builder toolchainBuilder : builder.getToolchainBuilderList()) {
+        toolchainBuilder.mergeFrom(configuration);
+      }
+      return this;
+    }
+
+    /** Appends the snippet {@code configuration} to all previously added toolchains. */
+    public CrosstoolBuilder appendToAllToolchains(String... configuration) throws IOException {
+      CToolchain.Builder toolchainBuilder = CToolchain.newBuilder();
+      TextFormat.merge(Joiner.on("\n").join(configuration), toolchainBuilder);
+      appendToAllToolchains(toolchainBuilder.buildPartial());
+      return this;
+    }
+
+    /** Returns the text proto containing the crosstool. */
+    public String build() {
+      return TextFormat.printToString(builder.build());
+    }
+  }
+
   /** Filter to remove implicit crosstool artifact and module map inputs of C/C++ rules. */
   public static final Predicate<Artifact> CC_ARTIFACT_FILTER =
       new Predicate<Artifact>() {
@@ -617,6 +687,31 @@ public abstract class MockCcSupport {
   }
 
   /**
+   * Create a new crosstool configuration specified by {@code builder}.
+   *
+   * <p>If used from a {@code BuildViewTestCase}, make sure to call {@code
+   * BuildViewTestCase.invalidatePackages} after calling this method to force re-loading of the
+   * crosstool's BUILD files.
+   */
+  public void setupCrosstoolFromScratch(MockToolsConfig config, CrosstoolBuilder builder)
+      throws IOException {
+    if (config.isRealFileSystem()) {
+      throw new RuntimeException(
+          "Cannot use setupCrosstoolFromScratch when config.isRealFileSystem() is true; "
+              + "use this function only for unit tests.");
+    }
+    // TODO(klimek): Get the version information from the crosstool builder and set up the
+    // crosstool with that information.
+    createCrosstoolPackage(
+        config,
+        /*addEmbeddedRuntimes=*/ false,
+        /*addModuleMap=*/ true,
+        null,
+        null,
+        builder.build());
+  }
+
+  /**
    * Create a crosstool package. For integration tests, it actually links in a working crosstool,
    * for all other tests, it only creates a dummy package, with a working CROSSTOOL file.
    *