Expand RedundantTryCatchRemovingTransformer to cover cases of handler blocks with types provably never thrown in the workspace

Author: Col-E

recaf-core/src/main/java/software/coley/recaf/services/deobfuscation/transform/generic/ExceptionCollectionTransformer.java

@@ -0,0 +1,96 @@
+package software.coley.recaf.services.deobfuscation.transform.generic;
+
+import jakarta.annotation.Nonnull;
+import jakarta.enterprise.context.Dependent;
+import jakarta.inject.Inject;
+import org.objectweb.asm.ClassReader;
+import org.objectweb.asm.MethodVisitor;
+import org.objectweb.asm.Opcodes;
+import software.coley.recaf.info.ClassInfo;
+import software.coley.recaf.info.JvmClassInfo;
+import software.coley.recaf.info.properties.builtin.ThrowableProperty;
+import software.coley.recaf.path.ClassPathNode;
+import software.coley.recaf.services.inheritance.InheritanceGraph;
+import software.coley.recaf.services.inheritance.InheritanceGraphService;
+import software.coley.recaf.services.transform.JvmClassTransformer;
+import software.coley.recaf.services.transform.JvmTransformerContext;
+import software.coley.recaf.services.transform.TransformationException;
+import software.coley.recaf.util.visitors.SkippingClassVisitor;
+import software.coley.recaf.util.visitors.SkippingMethodVisitor;
+import software.coley.recaf.workspace.model.Workspace;
+import software.coley.recaf.workspace.model.bundle.JvmClassBundle;
+import software.coley.recaf.workspace.model.resource.WorkspaceResource;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * A transformer that collects information about exceptions in the workspace.
+ *
+ * @author Matt Coley
+ */
+@Dependent
+public class ExceptionCollectionTransformer implements JvmClassTransformer, Opcodes {
+	private final Set<String> thrownExceptions = new HashSet<>();
+	private final InheritanceGraphService graphService;
+	private InheritanceGraph inheritanceGraph;
+
+	@Inject
+	public ExceptionCollectionTransformer(@Nonnull InheritanceGraphService graphService) {
+		this.graphService = graphService;
+
+		thrownExceptions.add("java/lang/Throwable");
+		thrownExceptions.add("java/lang/Exception");
+	}
+
+	@Override
+	public void setup(@Nonnull JvmTransformerContext context, @Nonnull Workspace workspace) {
+		inheritanceGraph = graphService.getOrCreateInheritanceGraph(workspace);
+	}
+
+	@Override
+	public void transform(@Nonnull JvmTransformerContext context, @Nonnull Workspace workspace,
+	                      @Nonnull WorkspaceResource resource, @Nonnull JvmClassBundle bundle,
+	                      @Nonnull JvmClassInfo initialClassState) throws TransformationException {
+		initialClassState.getClassReader().accept(new SkippingClassVisitor() {
+			@Override
+			public MethodVisitor visitMethod(int access, String name, String descriptor, String signature, String[] exceptions) {
+				return new SkippingMethodVisitor() {
+					@Override
+					public void visitTypeInsn(int opcode, String type) {
+						// Collect "new T" where "T" is a throwable type.
+						if (opcode != NEW)
+							return;
+						ClassPathNode path = workspace.findClass(false, type);
+						if (path == null)
+							return;
+						if (ThrowableProperty.get(path.getValue()) || inheritanceGraph.isAssignableFrom("java/lang/Throwable", type)) {
+							// The constructed type is an exception type,
+							// so we should add it and all parents to the known thrown types.
+							ClassInfo exInfo = path.getValue();
+							while (thrownExceptions.add(exInfo.getName()) && exInfo.getSuperName() != null) {
+								path = workspace.findClass(false, exInfo.getSuperName());
+								if (path == null)
+									break;
+							}
+						}
+					}
+				};
+			}
+		}, ClassReader.SKIP_FRAMES | ClassReader.SKIP_DEBUG);
+	}
+
+	@Nonnull
+	@Override
+	public String name() {
+		return "Exception metadata collection";
+	}
+
+	/**
+	 * @return Set of all exception types thrown in code defined in the workspace.
+	 */
+	@Nonnull
+	public Set<String> getThrownExceptions() {
+		return thrownExceptions;
+	}
+}