Change Painless regex node to use SField instead of Globals (#47944)

* Change Painless regex node to use SField instead of Globals

* Use reflection instead of ASM to specify modifiers

* Remove synthetic from SField

modules/lang-painless/src/main/java/org/elasticsearch/painless/ClassWriter.java

@@ -27,6 +27,7 @@ import org.objectweb.asm.util.Printer;
 import org.objectweb.asm.util.TraceClassVisitor;
 
 import java.io.Closeable;
+import java.lang.reflect.Modifier;
 import java.util.BitSet;
 
 /**
@@ -35,6 +36,30 @@ import java.util.BitSet;
  */
 public class ClassWriter implements Closeable  {
 
+    /**
+     * Converts Java reflection modifiers to ASM access constants.
+     * @param modifiers Java reflection {@code Modifiers}
+     * @param synthetic {@code true} if the item is synthetically generated
+     * @return ASM access constants
+     */
+    public static int buildAccess(int modifiers, boolean synthetic) {
+        int access = synthetic ? Opcodes.ACC_SYNTHETIC : 0;
+
+        if (Modifier.isFinal(modifiers))        access |= Opcodes.ACC_FINAL;
+        if (Modifier.isInterface(modifiers))    access |= Opcodes.ACC_INTERFACE;
+        if (Modifier.isNative(modifiers))       access |= Opcodes.ACC_NATIVE;
+        if (Modifier.isPrivate(modifiers))      access |= Opcodes.ACC_PRIVATE;
+        if (Modifier.isProtected(modifiers))    access |= Opcodes.ACC_PROTECTED;
+        if (Modifier.isPublic(modifiers))       access |= Opcodes.ACC_PUBLIC;
+        if (Modifier.isStatic(modifiers))       access |= Opcodes.ACC_STATIC;
+        if (Modifier.isStrict(modifiers))       access |= Opcodes.ACC_STRICT;
+        if (Modifier.isSynchronized(modifiers)) access |= Opcodes.ACC_SYNCHRONIZED;
+        if (Modifier.isTransient(modifiers))    access |= Opcodes.ACC_TRANSIENT;
+        if (Modifier.isVolatile(modifiers))     access |= Opcodes.ACC_VOLATILE;
+
+        return access;
+    }
+
     protected final CompilerSettings compilerSettings;
     protected final BitSet statements;
 

modules/lang-painless/src/main/java/org/elasticsearch/painless/node/ECallLocal.java

@@ -34,15 +34,13 @@ import org.objectweb.asm.Label;
 import org.objectweb.asm.Type;
 import org.objectweb.asm.commons.Method;
 
+import java.lang.reflect.Modifier;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
 import java.util.Set;
 
 import static org.elasticsearch.painless.WriterConstants.CLASS_TYPE;
-import static org.objectweb.asm.Opcodes.ACC_PRIVATE;
-import static org.objectweb.asm.Opcodes.ACC_PUBLIC;
-import static org.objectweb.asm.Opcodes.ACC_STATIC;
 
 /**
  * Represents a user-defined call.
@@ -144,13 +142,13 @@ public final class ECallLocal extends AExpression {
             actual = classBinding.returnType;
             bindingName = scriptRoot.getNextSyntheticName("class_binding");
             scriptRoot.getClassNode().addField(new SField(location,
-                    ACC_PRIVATE, bindingName, classBinding.javaConstructor.getDeclaringClass(), null));
+                    Modifier.PRIVATE, bindingName, classBinding.javaConstructor.getDeclaringClass(), null));
         } else if (instanceBinding != null) {
             typeParameters = new ArrayList<>(instanceBinding.typeParameters);
             actual = instanceBinding.returnType;
             bindingName = scriptRoot.getNextSyntheticName("instance_binding");
-            scriptRoot.getClassNode().addField(new SField(location,
-                    ACC_STATIC | ACC_PUBLIC, bindingName, instanceBinding.targetInstance.getClass(), instanceBinding.targetInstance));
+            scriptRoot.getClassNode().addField(new SField(location, Modifier.STATIC | Modifier.PUBLIC,
+                    bindingName, instanceBinding.targetInstance.getClass(), instanceBinding.targetInstance));
         } else {
             throw new IllegalStateException("Illegal tree structure.");
         }

modules/lang-painless/src/main/java/org/elasticsearch/painless/node/ERegex.java

@@ -29,6 +29,7 @@ import org.elasticsearch.painless.MethodWriter;
 import org.elasticsearch.painless.ScriptRoot;
 import org.elasticsearch.painless.WriterConstants;
 
+import java.lang.reflect.Modifier;
 import java.util.Set;
 import java.util.regex.Pattern;
 import java.util.regex.PatternSyntaxException;
@@ -87,8 +88,10 @@ public final class ERegex extends AExpression {
                     new IllegalArgumentException("Error compiling regex: " + e.getDescription()));
         }
 
-        constant = new Constant(
-            location, MethodWriter.getType(Pattern.class), "regexAt$" + location.getOffset(), this::initializeConstant);
+        String name = scriptRoot.getNextSyntheticName("regex");
+        scriptRoot.getClassNode().addField(
+                new SField(location, Modifier.FINAL | Modifier.STATIC | Modifier.PRIVATE, name, Pattern.class, null));
+        constant = new Constant(location, MethodWriter.getType(Pattern.class), name, this::initializeConstant);
         actual = Pattern.class;
     }
 

modules/lang-painless/src/main/java/org/elasticsearch/painless/node/SClass.java

@@ -303,16 +303,6 @@ public final class SClass extends AStatement {
         if (false == globals.getConstantInitializers().isEmpty()) {
             Collection<Constant> inits = globals.getConstantInitializers().values();
 
-            // Fields
-            for (Constant constant : inits) {
-                classVisitor.visitField(
-                        Opcodes.ACC_FINAL | Opcodes.ACC_PRIVATE | Opcodes.ACC_STATIC,
-                        constant.name,
-                        constant.type.getDescriptor(),
-                        null,
-                        null).visitEnd();
-            }
-
             // Initialize the constants in a static initializer
             final MethodWriter clinit = new MethodWriter(Opcodes.ACC_STATIC,
                     WriterConstants.CLINIT, classVisitor, globals.getStatements(), settings);

modules/lang-painless/src/main/java/org/elasticsearch/painless/node/SField.java

@@ -35,7 +35,7 @@ import java.util.Set;
  */
 public class SField extends ANode {
 
-    private final int access;
+    private final int modifiers;
     private final String name;
     private final Class<?> type;
     private final Object instance;
@@ -43,15 +43,15 @@ public class SField extends ANode {
     /**
      * Standard constructor.
      * @param location original location in the source
-     * @param access asm constants for field modifiers
+     * @param modifiers java modifiers for the field
      * @param name name of the field
      * @param type type of the field
      * @param instance initial value for the field
      */
-    public SField(Location location, int access, String name, Class<?> type, Object instance) {
+    public SField(Location location, int modifiers, String name, Class<?> type, Object instance) {
         super(location);
 
-        this.access = access;
+        this.modifiers = modifiers;
         this.name = name;
         this.type = type;
         this.instance = instance;
@@ -86,7 +86,8 @@ public class SField extends ANode {
     }
 
     void write(ClassWriter classWriter) {
-        classWriter.getClassVisitor().visitField(access, name, Type.getType(type).getDescriptor(), null, null).visitEnd();
+        classWriter.getClassVisitor().visitField(
+                ClassWriter.buildAccess(modifiers, true), name, Type.getType(type).getDescriptor(), null, null).visitEnd();
     }
 
     @Override