Remove unnecessary class initializations

Author: Christian Wimmer

compiler/src/org.graalvm.compiler.nodes/src/org/graalvm/compiler/nodes/SimplifyingGraphDecoder.java

@@ -38,8 +38,6 @@
 import org.graalvm.compiler.graph.Edges;
 import org.graalvm.compiler.graph.Node;
 import org.graalvm.compiler.graph.NodeClass;
-import org.graalvm.compiler.nodes.spi.Canonicalizable;
-import org.graalvm.compiler.nodes.spi.CanonicalizerTool;
 import org.graalvm.compiler.nodeinfo.InputType;
 import org.graalvm.compiler.nodeinfo.NodeInfo;
 import org.graalvm.compiler.nodes.calc.FloatingNode;
@@ -49,6 +47,8 @@
 import org.graalvm.compiler.nodes.java.ArrayLengthNode;
 import org.graalvm.compiler.nodes.java.LoadFieldNode;
 import org.graalvm.compiler.nodes.java.LoadIndexedNode;
+import org.graalvm.compiler.nodes.spi.Canonicalizable;
+import org.graalvm.compiler.nodes.spi.CanonicalizerTool;
 import org.graalvm.compiler.nodes.spi.CoreProviders;
 import org.graalvm.compiler.nodes.spi.CoreProvidersDelegate;
 import org.graalvm.compiler.nodes.util.GraphUtil;
@@ -333,7 +333,11 @@ private void handleCanonicalization(LoopScope loopScope, int nodeOrderId, FixedN
                 }
             }
             if (!node.isDeleted()) {
-                GraphUtil.unlinkFixedNode((FixedWithNextNode) node);
+                if (node instanceof WithExceptionNode) {
+                    GraphUtil.unlinkAndKillExceptionEdge((WithExceptionNode) node);
+                } else {
+                    GraphUtil.unlinkFixedNode((FixedWithNextNode) node);
+                }
                 node.replaceAtUsagesAndDelete(canonical);
             }
             assert lookupNode(loopScope, nodeOrderId) == node;

compiler/src/org.graalvm.compiler.phases.common/src/org/graalvm/compiler/phases/common/CanonicalizerPhase.java

@@ -57,6 +57,7 @@
 import org.graalvm.compiler.nodes.StructuredGraph;
 import org.graalvm.compiler.nodes.StructuredGraph.StageFlag;
 import org.graalvm.compiler.nodes.ValueNode;
+import org.graalvm.compiler.nodes.WithExceptionNode;
 import org.graalvm.compiler.nodes.calc.FloatingNode;
 import org.graalvm.compiler.nodes.spi.Canonicalizable;
 import org.graalvm.compiler.nodes.spi.Canonicalizable.BinaryCommutative;
@@ -490,6 +491,49 @@ private boolean performReplacement(final Node node, Node newCanonical) {
                         fixed.replaceAtPredecessor(canonical);
                         GraphUtil.killCFG(fixed);
                         return true;
+
+                    } else if (fixed instanceof WithExceptionNode) {
+                        /*
+                         * A fixed node with an exception edge is handled similarly to a
+                         * FixedWithNextNode. The only difference is that the exception edge needs
+                         * to be killed as part of canonicalization (unless the canonical node is a
+                         * new WithExceptionNode too).
+                         */
+                        WithExceptionNode withException = (WithExceptionNode) fixed;
+
+                        // When removing a fixed node, new canonicalization
+                        // opportunities for its successor may arise
+                        assert withException.next() != null;
+                        tool.addToWorkList(withException.next());
+                        if (canonical == null) {
+                            // case 3
+                            node.replaceAtUsages(null);
+                            GraphUtil.unlinkAndKillExceptionEdge(withException);
+                            GraphUtil.killWithUnusedFloatingInputs(withException);
+                        } else if (canonical instanceof FloatingNode) {
+                            // case 4
+                            withException.killExceptionEdge();
+                            graph.replaceSplitWithFloating(withException, (FloatingNode) canonical, withException.next());
+                        } else {
+                            assert canonical instanceof FixedNode;
+                            if (canonical.predecessor() == null) {
+                                assert !canonical.cfgSuccessors().iterator().hasNext() : "replacement " + canonical + " shouldn't have successors";
+                                // case 5
+                                if (canonical instanceof WithExceptionNode) {
+                                    graph.replaceWithExceptionSplit(withException, (WithExceptionNode) canonical);
+                                } else {
+                                    withException.killExceptionEdge();
+                                    graph.replaceSplitWithFixed(withException, (FixedWithNextNode) canonical, withException.next());
+                                }
+                            } else {
+                                assert canonical.cfgSuccessors().iterator().hasNext() : "replacement " + canonical + " should have successors";
+                                // case 6
+                                node.replaceAtUsages(canonical);
+                                GraphUtil.unlinkAndKillExceptionEdge(withException);
+                                GraphUtil.killWithUnusedFloatingInputs(withException);
+                            }
+                        }
+
                     } else {
                         assert fixed instanceof FixedWithNextNode;
                         FixedWithNextNode fixedWithNext = (FixedWithNextNode) fixed;

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/classinitialization/EnsureClassInitializedNode.java

@@ -25,6 +25,7 @@
 package com.oracle.svm.core.classinitialization;
 
 import org.graalvm.compiler.core.common.type.StampFactory;
+import org.graalvm.compiler.graph.Node;
 import org.graalvm.compiler.graph.Node.NodeIntrinsicFactory;
 import org.graalvm.compiler.graph.NodeClass;
 import org.graalvm.compiler.nodeinfo.InputType;
@@ -37,17 +38,18 @@
 import org.graalvm.compiler.nodes.WithExceptionNode;
 import org.graalvm.compiler.nodes.graphbuilderconf.GraphBuilderContext;
 import org.graalvm.compiler.nodes.memory.SingleMemoryKill;
+import org.graalvm.compiler.nodes.spi.Canonicalizable;
+import org.graalvm.compiler.nodes.spi.CanonicalizerTool;
+import org.graalvm.compiler.nodes.spi.CoreProviders;
 import org.graalvm.compiler.nodes.spi.Lowerable;
-import org.graalvm.compiler.nodes.spi.Simplifiable;
-import org.graalvm.compiler.nodes.spi.SimplifierTool;
 import org.graalvm.compiler.nodes.type.StampTool;
 import org.graalvm.word.LocationIdentity;
 
 import jdk.vm.ci.meta.ResolvedJavaType;
 
 @NodeInfo(size = NodeSize.SIZE_16, cycles = NodeCycles.CYCLES_2, cyclesRationale = "Class initialization only runs at most once at run time, so the amortized cost is only the is-initialized check")
 @NodeIntrinsicFactory
-public class EnsureClassInitializedNode extends WithExceptionNode implements Simplifiable, StateSplit, SingleMemoryKill, Lowerable {
+public class EnsureClassInitializedNode extends WithExceptionNode implements Canonicalizable, StateSplit, SingleMemoryKill, Lowerable {
 
     public static final NodeClass<EnsureClassInitializedNode> TYPE = NodeClass.create(EnsureClassInitializedNode.class);
 
@@ -95,15 +97,61 @@ public boolean hasSideEffect() {
         return true;
     }
 
-    @Override
-    public void simplify(SimplifierTool tool) {
+    public ResolvedJavaType constantTypeOrNull(CoreProviders providers) {
         if (hub.isConstant()) {
-            ResolvedJavaType type = tool.getConstantReflection().asJavaType(hub.asConstant());
-            if (type != null && type.isInitialized()) {
-                killExceptionEdge();
-                graph().removeSplit(this, next());
-                return;
+            return providers.getConstantReflection().asJavaType(hub.asConstant());
+        } else {
+            return null;
+        }
+    }
+
+    @Override
+    public Node canonical(CanonicalizerTool tool) {
+        ResolvedJavaType type = constantTypeOrNull(tool);
+        if (type != null) {
+            for (FrameState cur = stateAfter; cur != null; cur = cur.outerFrameState()) {
+                if (!needsRuntimeInitialization(cur.getMethod().getDeclaringClass(), type)) {
+                    return null;
+                }
+            }
+        }
+        return this;
+    }
+
+    /**
+     * Return true if the type needs to be initialized at run time, i.e., it has not been already
+     * initialized during image generation or initialization is implied by the declaringClass.
+     */
+    public static boolean needsRuntimeInitialization(ResolvedJavaType declaringClass, ResolvedJavaType type) {
+        if (type.isInitialized() || type.isArray() || type.equals(declaringClass)) {
+            /*
+             * The simple cases: the type is already initialized, or the type is an exact match with
+             * the declaring class.
+             */
+            return false;
+
+        } else if (declaringClass.isInterface()) {
+            /*
+             * Initialization of an interface does not trigger initialization of superinterfaces.
+             * Regardless whether any of the involved interfaces declares default methods.
+             */
+            return true;
+
+        } else if (type.isAssignableFrom(declaringClass)) {
+            if (type.isInterface()) {
+                /*
+                 * Initialization of a class only triggers initialization of an implemented
+                 * interface if that interface declares default methods.
+                 */
+                return !type.declaresDefaultMethods();
+            } else {
+                /* Initialization of a class triggers initialization of all superclasses. */
+                return false;
             }
+
+        } else {
+            /* No relationship between the two types. */
+            return true;
         }
     }
 

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/SVMHost.java

@@ -109,7 +109,6 @@
 import com.oracle.svm.hosted.substitute.UnsafeAutomaticSubstitutionProcessor;
 import com.oracle.svm.util.ReflectionUtil;
 
-import jdk.vm.ci.meta.Constant;
 import jdk.vm.ci.meta.DeoptimizationReason;
 import jdk.vm.ci.meta.ResolvedJavaField;
 import jdk.vm.ci.meta.ResolvedJavaMethod;
@@ -652,10 +651,9 @@ private void checkClassInitializerSideEffect(BigBang bb, AnalysisMethod method,
              */
             classInitializerSideEffect.put(method, true);
         } else if (n instanceof EnsureClassInitializedNode) {
-            Constant constantHub = ((EnsureClassInitializedNode) n).getHub().asConstant();
-            if (constantHub != null) {
-                AnalysisType type = (AnalysisType) bb.getProviders().getConstantReflection().asJavaType(constantHub);
-                initializedClasses.computeIfAbsent(method, k -> new HashSet<>()).add(type);
+            ResolvedJavaType type = ((EnsureClassInitializedNode) n).constantTypeOrNull(bb.getProviders());
+            if (type != null) {
+                initializedClasses.computeIfAbsent(method, k -> new HashSet<>()).add((AnalysisType) type);
             } else {
                 classInitializerSideEffect.put(method, true);
             }

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/classinitialization/EarlyClassInitializerAnalysis.java

@@ -55,6 +55,7 @@
 import org.graalvm.compiler.phases.util.Providers;
 
 import com.oracle.svm.core.ParsingReason;
+import com.oracle.svm.core.classinitialization.EnsureClassInitializedNode;
 import com.oracle.svm.core.graal.thread.VMThreadLocalAccess;
 import com.oracle.svm.core.option.HostedOptionValues;
 import com.oracle.svm.core.util.VMError;
@@ -197,7 +198,7 @@ final class AbortOnUnitializedClassPlugin extends NoClassInitializationPlugin {
         @Override
         public boolean apply(GraphBuilderContext b, ResolvedJavaType type, Supplier<FrameState> frameState, ValueNode[] classInit) {
             ResolvedJavaMethod clinitMethod = b.getGraph().method();
-            if (type.isInitialized() || type.isArray() || type.equals(clinitMethod.getDeclaringClass())) {
+            if (!EnsureClassInitializedNode.needsRuntimeInitialization(clinitMethod.getDeclaringClass(), type)) {
                 return false;
             }
             if (classInitializationSupport.computeInitKindAndMaybeInitializeClass(ConfigurableClassInitialization.getJavaClass(type), true, analyzedClasses) != InitKind.RUN_TIME) {

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/phases/HostedGraphKit.java

@@ -101,7 +101,7 @@ protected Instance createGraphBuilderInstance(GraphBuilderConfiguration graphBui
     }
 
     public void emitEnsureInitializedCall(ResolvedJavaType type) {
-        if (SubstrateClassInitializationPlugin.needsRuntimeInitialization(graph.method().getDeclaringClass(), type)) {
+        if (EnsureClassInitializedNode.needsRuntimeInitialization(graph.method().getDeclaringClass(), type)) {
             ValueNode hub = createConstant(getConstantReflection().asJavaClass(type), JavaKind.Object);
             appendWithUnwind(new EnsureClassInitializedNode(hub));
         }

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/phases/SubstrateClassInitializationPlugin.java

@@ -60,7 +60,7 @@ public void loadReferencedType(GraphBuilderContext builder, ConstantPool constan
 
     @Override
     public boolean apply(GraphBuilderContext builder, ResolvedJavaType type, Supplier<FrameState> frameState, ValueNode[] classInit) {
-        if (needsRuntimeInitialization(builder.getMethod().getDeclaringClass(), type)) {
+        if (EnsureClassInitializedNode.needsRuntimeInitialization(builder.getMethod().getDeclaringClass(), type)) {
             emitEnsureClassInitialized(builder, SubstrateObjectConstant.forObject(host.dynamicHub(type)), frameState.get());
             /*
              * The classInit value is only registered with Invoke nodes. Since we do not need that,
@@ -79,12 +79,4 @@ private static void emitEnsureClassInitialized(GraphBuilderContext builder, Java
         EnsureClassInitializedNode node = new EnsureClassInitializedNode(hub, frameState);
         builder.add(node);
     }
-
-    /**
-     * Return true if the type needs to be initialized at run time, i.e., it has not been already
-     * initialized during image generation.
-     */
-    static boolean needsRuntimeInitialization(ResolvedJavaType declaringClass, ResolvedJavaType type) {
-        return !declaringClass.equals(type) && !type.isInitialized() && !type.isArray();
-    }
 }