Do not duplicate build variables, reuse variables from cc toolchain

Before this cl each linking and compilation action would contain a full copy of
all build variables. However, some build variables can be reused, for the
memory consumption benefit. With this cl, we contruct a Variables instance in
the CcToolchain, and make it a parent of all per-linking and per-compilation
variables.

RELNOTES: None.
PiperOrigin-RevId: 169233756

2 files changed, 19 insertions, 2 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/rules/cpp/CcToolchainProviderTest.java b/src/test/java/com/google/devtools/build/lib/rules/cpp/CcToolchainProviderTest.java
index 20891db1b5..bc93ba92b2 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/cpp/CcToolchainProviderTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/cpp/CcToolchainProviderTest.java
@@ -20,6 +20,7 @@ import com.google.common.testing.EqualsTester;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
 import com.google.devtools.build.lib.collect.nestedset.Order;
+import com.google.devtools.build.lib.rules.cpp.CcToolchainFeatures.Variables;
 import com.google.devtools.build.lib.util.Pair;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import org.junit.Test;
@@ -54,7 +55,7 @@ public class CcToolchainProviderTest {
             CppCompilationContext.EMPTY,
             false,
             false,
-            ImmutableMap.<String, String>of(),
+            Variables.EMPTY,
             ImmutableList.<Artifact>of(),
             NestedSetBuilder.<Pair<String, String>>emptySet(Order.COMPILE_ORDER),
             null,
@@ -84,7 +85,7 @@ public class CcToolchainProviderTest {
             CppCompilationContext.EMPTY,
             false,
             false,
-            ImmutableMap.<String, String>of(),
+            Variables.EMPTY,
             ImmutableList.<Artifact>of(),
             NestedSetBuilder.<Pair<String, String>>emptySet(Order.COMPILE_ORDER),
             null,
diff --git a/src/test/java/com/google/devtools/build/lib/rules/cpp/CompileBuildVariablesTest.java b/src/test/java/com/google/devtools/build/lib/rules/cpp/CompileBuildVariablesTest.java
index 20db405131..89b7a3b992 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/cpp/CompileBuildVariablesTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/cpp/CompileBuildVariablesTest.java
@@ -124,4 +124,20 @@ public class CompileBuildVariablesTest extends BuildViewTestCase {
         Variables.toStringList(variables, CppModel.USER_COMPILE_FLAGS_VARIABLE_NAME);
     assertThat(copts).containsExactly("-foo").inOrder();
   }
+
+  @Test
+  public void testPresenceOfSysrootBuildVariable() throws Exception {
+    AnalysisMock.get()
+        .ccSupport()
+        .setupCrosstool(mockToolsConfig, "builtin_sysroot: '/usr/local/custom-sysroot'");
+    useConfiguration();
+
+    scratch.file("x/BUILD", "cc_binary(name = 'bin', srcs = ['bin.cc'])");
+    scratch.file("x/bin.cc");
+
+    Variables variables = getCompileBuildVariables("//x:bin", "bin");
+
+    assertThat(variables.getStringVariable(CppModel.SYSROOT_VARIABLE_NAME))
+        .isEqualTo("/usr/local/custom-sysroot");
+  }
 }