Move specialized execute method code into an external phase

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

@@ -211,6 +211,7 @@ ScriptRoot compile(Loader loader, String name, String source, CompilerSettings s
         SClass root = Walker.buildPainlessTree(scriptClassInfo, name, source, settings, painlessLookup, null);
         ScriptRoot scriptRoot = root.analyze(painlessLookup, settings);
         ClassNode classNode = root.writeClass();
+        ScriptInjectionPhase.phase(scriptRoot, classNode);
         Map<String, Object> statics = classNode.write();
 
         try {
@@ -240,8 +241,9 @@ ScriptRoot compile(Loader loader, String name, String source, CompilerSettings s
     byte[] compile(String name, String source, CompilerSettings settings, Printer debugStream) {
         ScriptClassInfo scriptClassInfo = new ScriptClassInfo(painlessLookup, scriptClass);
         SClass root = Walker.buildPainlessTree(scriptClassInfo, name, source, settings, painlessLookup, debugStream);
-        root.analyze(painlessLookup, settings);
+        ScriptRoot scriptRoot = root.analyze(painlessLookup, settings);
         ClassNode classNode = root.writeClass();
+        ScriptInjectionPhase.phase(scriptRoot, classNode);
         classNode.write();
 
         return classNode.getBytes();

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

@@ -502,7 +502,7 @@ public void invokeMethodCall(PainlessMethod painlessMethod) {
             // method since java 8 did not check, but java 9 and 10 do
             if (painlessMethod.javaMethod.getDeclaringClass().isInterface()) {
                 visitMethodInsn(Opcodes.INVOKESTATIC, type.getInternalName(),
-                        painlessMethod.javaMethod.getName(), painlessMethod.methodType.toMethodDescriptorString(), true);
+                        painlessMethod.javaMethod.getName(), method.getDescriptor(), true);
             } else {
                 invokeStatic(type, method);
             }

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

@@ -87,9 +87,9 @@ public boolean isFinal() {
     public static class FunctionScope extends Scope {
 
         protected final Class<?> returnType;
-        protected final Set<String> usedVariables = new HashSet<>();
 
         public FunctionScope(Class<?> returnType) {
+            super(new HashSet<>());
             this.returnType = Objects.requireNonNull(returnType);
         }
 
@@ -128,10 +128,6 @@ public Class<?> getReturnType() {
         public String getReturnCanonicalTypeName() {
             return PainlessLookupUtility.typeToCanonicalTypeName(returnType);
         }
-
-        public Set<String> getUsedVariables() {
-            return Collections.unmodifiableSet(usedVariables);
-        }
     }
 
     /**
@@ -150,6 +146,7 @@ public static class LambdaScope extends Scope {
         protected final Set<Variable> captures = new HashSet<>();
 
         protected LambdaScope(Scope parent, Class<?> returnType) {
+            super(parent.usedVariables);
             this.parent = parent;
             this.returnType = returnType;
         }
@@ -180,6 +177,8 @@ public Variable getVariable(Location location, String name) {
                 variable = parent.getVariable(location, name);
                 variable = new Variable(variable.getType(), variable.getName(), true);
                 captures.add(variable);
+            } else {
+                usedVariables.add(name);
             }
 
             return variable;
@@ -213,6 +212,7 @@ public static class BlockScope extends Scope {
         protected final Scope parent;
 
         protected BlockScope(Scope parent) {
+            super(parent.usedVariables);
             this.parent = parent;
         }
 
@@ -238,6 +238,8 @@ public Variable getVariable(Location location, String name) {
 
             if (variable == null) {
                 variable = parent.getVariable(location, name);
+            } else {
+                usedVariables.add(name);
             }
 
             return variable;
@@ -263,9 +265,10 @@ public static FunctionScope newFunctionScope(Class<?> returnType) {
     }
 
     protected final Map<String, Variable> variables = new HashMap<>();
+    protected final Set<String> usedVariables;
 
-    protected Scope() {
-        // do nothing
+    protected Scope(Set<String> usedVariables) {
+        this.usedVariables = usedVariables;
     }
 
     /**
@@ -312,4 +315,13 @@ public boolean isInternalVariableDefined(String name) {
     public Variable getInternalVariable(Location location, String name) {
         return getVariable(location, "#" + name);
     }
+
+    /**
+     * Returns the set of variables used within a top-level {@link FunctionScope}
+     * including local variables no longer in scope upon completion of writing a
+     * function to ASM bytecode.
+     */
+    public Set<String> getUsedVariables() {
+        return Collections.unmodifiableSet(usedVariables);
+    }
 }