Merge pull request #18958 from rmuir/explicit_casts

Fix explicit casts and improve tests.

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

@@ -34,6 +34,11 @@ public final class CompilerSettings {
      */
     public static final String PICKY = "picky";
     
+    /**
+     * For testing: do not use.
+     */
+    public static final String INITIAL_CALL_SITE_DEPTH = "initialCallSiteDepth";
+
     /**
      * The maximum number of statements allowed to be run in a loop.
      */
@@ -45,6 +50,11 @@ public final class CompilerSettings {
      */
     private boolean picky = false;
     
+    /**
+     * For testing. Do not use.
+     */
+    private int initialCallSiteDepth = 0;
+
     /**
      * Returns the value for the cumulative total number of statements that can be made in all loops
      * in a script before an exception is thrown.  This attempts to prevent infinite loops.  Note if
@@ -78,4 +88,20 @@ public final class CompilerSettings {
     public void setPicky(boolean picky) {
       this.picky = picky;
     }
+    
+    /**
+     * Returns initial call site depth. This means we pretend we've already seen N different types,
+     * to better exercise fallback code in tests.
+     */
+    public int getInitialCallSiteDepth() {
+        return initialCallSiteDepth;
+    }
+    
+    /**
+     * For testing megamorphic fallbacks. Do not use.
+     * @see #getInitialCallSiteDepth()
+     */
+    public void setInitialCallSiteDepth(int depth) {
+        this.initialCallSiteDepth = depth;
+    }
 }

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

@@ -287,6 +287,7 @@ public final class Def {
                      CallSite nested = DefBootstrap.bootstrap(lookup, 
                                                               call,
                                                               nestedType,
+                                                              0,
                                                               DefBootstrap.REFERENCE,
                                                               interfaceType.name);
                      filter = nested.dynamicInvoker();

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

@@ -27,6 +27,7 @@ import java.lang.invoke.MethodHandles;
 import java.lang.invoke.MethodHandles.Lookup;
 import java.lang.invoke.MethodType;
 import java.lang.invoke.MutableCallSite;
+import java.lang.invoke.WrongMethodTypeException;
 
 /**
  * Painless invokedynamic bootstrap for the call site.
@@ -80,10 +81,19 @@ public final class DefBootstrap {
     
     /**
      * static bootstrap parameter indicating the binary operator is part of compound assignment (e.g. +=).
-     * 
+     * <p>
+     * may require {@link MethodHandles#explicitCastArguments}, or a dynamic cast
+     * to cast back to the receiver's type, depending on types seen.
      */
     public static final int OPERATOR_COMPOUND_ASSIGNMENT = 1 << 1;
     
+    /**
+     * static bootstrap parameter indicating an explicit cast to the return type.
+     * <p>
+     * may require {@link MethodHandles#explicitCastArguments}, depending on types seen.
+     */
+    public static final int OPERATOR_EXPLICIT_CAST = 1 << 2;
+
     /**
      * CallSite that implements the polymorphic inlining cache (PIC).
      */
@@ -97,7 +107,7 @@ public final class DefBootstrap {
         private final Object[] args;
         int depth; // pkg-protected for testing
 
-        PIC(Lookup lookup, String name, MethodType type, int flavor, Object[] args) {
+        PIC(Lookup lookup, String name, MethodType type, int initialDepth, int flavor, Object[] args) {
             super(type);
             if (type.parameterType(0) != Object.class) {
                 throw new BootstrapMethodError("The receiver type (1st arg) of invokedynamic descriptor must be Object.");
@@ -106,6 +116,7 @@ public final class DefBootstrap {
             this.name = name;
             this.flavor = flavor;
             this.args = args;
+            this.depth = initialDepth;
 
             MethodHandle fallback = FALLBACK.bindTo(this)
               .asCollector(Object[].class, type.parameterCount())
@@ -226,11 +237,14 @@ public final class DefBootstrap {
         private final int flavor;
         private final int flags;
 
-        MIC(String name, MethodType type, int flavor, int flags) {
+        MIC(String name, MethodType type, int initialDepth, int flavor, int flags) {
             super(type);
             this.name = name;
             this.flavor = flavor;
             this.flags = flags;
+            if (initialDepth > 0) {
+                initialized = true;
+            }
             
             MethodHandle fallback = FALLBACK.bindTo(this)
               .asCollector(Object[].class, type.parameterCount())
@@ -248,7 +262,9 @@ public final class DefBootstrap {
                 case SHIFT_OPERATOR:
                     // shifts are treated as unary, as java allows long arguments without a cast (but bits are ignored)
                     MethodHandle unary = DefMath.lookupUnary(args[0].getClass(), name);
-                    if ((flags & OPERATOR_COMPOUND_ASSIGNMENT) != 0) {
+                    if ((flags & OPERATOR_EXPLICIT_CAST) != 0) {
+                        unary = DefMath.cast(type().returnType(), unary);
+                    } else if ((flags & OPERATOR_COMPOUND_ASSIGNMENT) != 0) {
                         unary = DefMath.cast(args[0].getClass(), unary);
                     }
                     return unary;
@@ -257,7 +273,9 @@ public final class DefBootstrap {
                         return lookupGeneric(); // can handle nulls, casts if supported
                     } else {
                         MethodHandle binary = DefMath.lookupBinary(args[0].getClass(), args[1].getClass(), name);
-                        if ((flags & OPERATOR_COMPOUND_ASSIGNMENT) != 0) {
+                        if ((flags & OPERATOR_EXPLICIT_CAST) != 0) {
+                            binary = DefMath.cast(type().returnType(), binary);
+                        } else if ((flags & OPERATOR_COMPOUND_ASSIGNMENT) != 0) {
                             binary = DefMath.cast(args[0].getClass(), binary);
                         }
                         return binary;
@@ -267,11 +285,15 @@ public final class DefBootstrap {
         }
         
         private MethodHandle lookupGeneric() {
-            if ((flags & OPERATOR_COMPOUND_ASSIGNMENT) != 0) {
+            MethodHandle target = DefMath.lookupGeneric(name);
-                return DefMath.lookupGenericWithCast(name);
+            if ((flags & OPERATOR_EXPLICIT_CAST) != 0) {
-            } else {
+                // static cast to the return type
-                return DefMath.lookupGeneric(name);
+                target = DefMath.dynamicCast(target, type().returnType());
+            } else if ((flags & OPERATOR_COMPOUND_ASSIGNMENT) != 0) {
+                // dynamic cast to the receiver's type
+                target = DefMath.dynamicCast(target);
             }
+            return target;
         }
         
         /**
@@ -288,7 +310,15 @@ public final class DefBootstrap {
             }
             
             final MethodType type = type();
-            final MethodHandle target = lookup(args).asType(type);
+            MethodHandle target = lookup(args);
+            // for math operators: WrongMethodType can be confusing. convert into a ClassCastException if they screw up.
+            try {
+                target = target.asType(type);
+            } catch (WrongMethodTypeException e) {
+                Exception exc = new ClassCastException("Cannot cast from: " + target.type().returnType() + " to " + type.returnType());
+                exc.initCause(e);
+                throw exc;
+            }
 
             final MethodHandle test;
             if (flavor == BINARY_OPERATOR || flavor == SHIFT_OPERATOR) {
@@ -384,12 +414,16 @@ public final class DefBootstrap {
     /**
      * invokeDynamic bootstrap method
      * <p>
-     * In addition to ordinary parameters, we also take a static parameter {@code flavor} which
+     * In addition to ordinary parameters, we also take some static parameters:
-     * tells us what type of dynamic call it is (and which part of whitelist to look at).
+     * <ul>
+     *   <li>{@code initialDepth}: initial call site depth. this is used to exercise megamorphic fallback.
+     *   <li>{@code flavor}: type of dynamic call it is (and which part of whitelist to look at).
+     *   <li>{@code args}: flavor-specific args.
+     * </ul>
      * <p>
      * see https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-6.html#jvms-6.5.invokedynamic
      */
-    public static CallSite bootstrap(Lookup lookup, String name, MethodType type, int flavor, Object... args) {
+    public static CallSite bootstrap(Lookup lookup, String name, MethodType type, int initialDepth, int flavor, Object... args) {
         // validate arguments
         switch(flavor) {
             // "function-call" like things get a polymorphic cache
@@ -408,7 +442,7 @@ public final class DefBootstrap {
                 if (args.length != numLambdas + 1) {
                     throw new BootstrapMethodError("Illegal number of parameters: expected " + numLambdas + " references");
                 }
-                return new PIC(lookup, name, type, flavor, args);
+                return new PIC(lookup, name, type, initialDepth, flavor, args);
             case LOAD:
             case STORE:
             case ARRAY_LOAD:
@@ -417,7 +451,7 @@ public final class DefBootstrap {
                 if (args.length > 0) {
                     throw new BootstrapMethodError("Illegal static bootstrap parameters for flavor: " + flavor);
                 }
-                return new PIC(lookup, name, type, flavor, args);
+                return new PIC(lookup, name, type, initialDepth, flavor, args);
             case REFERENCE:
                 if (args.length != 1) {
                     throw new BootstrapMethodError("Invalid number of parameters for reference call");
@@ -425,7 +459,7 @@ public final class DefBootstrap {
                 if (args[0] instanceof String == false) {
                     throw new BootstrapMethodError("Illegal parameter for reference call: " + args[0]);
                 }
-                return new PIC(lookup, name, type, flavor, args);
+                return new PIC(lookup, name, type, initialDepth, flavor, args);
 
             // operators get monomorphic cache, with a generic impl for a fallback
             case UNARY_OPERATOR:
@@ -442,11 +476,11 @@ public final class DefBootstrap {
                     // we just don't need it anywhere else.
                     throw new BootstrapMethodError("This parameter is only supported for BINARY_OPERATORs");
                 }
-                if ((flags & OPERATOR_COMPOUND_ASSIGNMENT) != 0 && flavor != BINARY_OPERATOR) {
+                if ((flags & OPERATOR_COMPOUND_ASSIGNMENT) != 0 && flavor != BINARY_OPERATOR && flavor != SHIFT_OPERATOR) {
                     // we just don't need it anywhere else.
-                    throw new BootstrapMethodError("This parameter is only supported for BINARY_OPERATORs");
+                    throw new BootstrapMethodError("This parameter is only supported for BINARY/SHIFT_OPERATORs");
                 }
-                return new MIC(name, type, flavor, flags);
+                return new MIC(name, type, initialDepth, flavor, flags);
             default:
                 throw new BootstrapMethodError("Illegal static bootstrap parameter for flavor: " + flavor);
         }

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

@@ -1027,25 +1027,7 @@ public class DefMath {
      * class if its not a boxed type.
      */
     private static Class<?> unbox(Class<?> clazz) {
-        if (clazz == Boolean.class) {
+        return MethodType.methodType(clazz).unwrap().returnType();
-            return boolean.class;
-        } else if (clazz == Byte.class) { 
-            return byte.class; 
-        } else if (clazz == Short.class) { 
-            return short.class; 
-        } else if (clazz == Character.class) {
-            return char.class;
-        } else if (clazz == Integer.class) {
-            return int.class;
-        } else if (clazz == Long.class) {
-            return long.class;
-        } else if (clazz == Float.class) {
-            return float.class;
-        } else if (clazz == Double.class) {
-            return double.class;
-        } else {
-            return clazz;
-        }
     }
     
     /** Unary promotion. All Objects are promoted to Object. */
@@ -1147,39 +1129,49 @@ public class DefMath {
         return TYPE_OP_MAPPING.get(Object.class).get(name);
     }
 
-    
     /**
      * Slow dynamic cast: casts {@code returnValue} to the runtime type of {@code lhs}
      * based upon inspection. If {@code lhs} is null, no cast takes place.
      * This is used for the generic fallback case of compound assignment.
      */
-    static Object dynamicCast(Object returnValue, Object lhs) {
+    static Object dynamicReceiverCast(Object returnValue, Object lhs) {
         if (lhs != null) {
-            Class<?> c = lhs.getClass();
+            return dynamicCast(lhs.getClass(), returnValue);
-            if (c == returnValue.getClass()) {
-                return returnValue;
-            }
-            if (c == Integer.class) {
-                return getNumber(returnValue).intValue();
-            } else if (c == Long.class) {
-                return getNumber(returnValue).longValue();
-            } else if (c == Double.class) {
-                return getNumber(returnValue).doubleValue();
-            } else if (c == Float.class) {
-                return getNumber(returnValue).floatValue();
-            } else if (c == Short.class) {
-                return getNumber(returnValue).shortValue();
-            } else if (c == Byte.class) {
-                return getNumber(returnValue).byteValue();
-            } else if (c == Character.class) {
-                return (char) getNumber(returnValue).intValue();
-            }
-            return lhs.getClass().cast(returnValue);
         } else {
             return returnValue;
         }
     }
     
+    /**
+     * Slow dynamic cast: casts {@code value} to an instance of {@code clazz}
+     * based upon inspection. If {@code lhs} is null, no cast takes place.
+     */
+    static Object dynamicCast(Class<?> clazz, Object value) {
+        if (value != null) {
+            if (clazz == value.getClass()) {
+                return value;
+            }
+            if (clazz == Integer.class) {
+                return getNumber(value).intValue();
+            } else if (clazz == Long.class) {
+                return getNumber(value).longValue();
+            } else if (clazz == Double.class) {
+                return getNumber(value).doubleValue();
+            } else if (clazz == Float.class) {
+                return getNumber(value).floatValue();
+            } else if (clazz == Short.class) {
+                return getNumber(value).shortValue();
+            } else if (clazz == Byte.class) {
+                return getNumber(value).byteValue();
+            } else if (clazz == Character.class) {
+                return (char) getNumber(value).intValue();
+            }
+            return clazz.cast(value);
+        } else {
+            return value;
+        }
+    }
+    
     /** Slowly returns a Number for o. Just for supporting dynamicCast */
     static Number getNumber(Object o) {
         if (o instanceof Number) {
@@ -1192,11 +1184,15 @@ public class DefMath {
     }
     
     private static final MethodHandle DYNAMIC_CAST;
+    private static final MethodHandle DYNAMIC_RECEIVER_CAST;
     static {
         final Lookup lookup = MethodHandles.lookup();
         try {
             DYNAMIC_CAST = lookup.findStatic(lookup.lookupClass(), 
                                             "dynamicCast", 
+                                            MethodType.methodType(Object.class, Class.class, Object.class));
+            DYNAMIC_RECEIVER_CAST = lookup.findStatic(lookup.lookupClass(), 
+                                                     "dynamicReceiverCast", 
                                                      MethodType.methodType(Object.class, Object.class, Object.class));
         } catch (ReflectiveOperationException e) {
             throw new AssertionError(e);
@@ -1204,16 +1200,24 @@ public class DefMath {
     }
 
     /** Looks up generic method, with a dynamic cast to the receiver's type. (compound assignment) */
-    public static MethodHandle lookupGenericWithCast(String name) {
+    public static MethodHandle dynamicCast(MethodHandle target) {
-        MethodHandle generic = lookupGeneric(name);
+        // adapt dynamic receiver cast to the generic method
-        // adapt dynamic cast to the generic method
+        MethodHandle cast = DYNAMIC_RECEIVER_CAST.asType(MethodType.methodType(target.type().returnType(), 
-        MethodHandle cast = DYNAMIC_CAST.asType(MethodType.methodType(generic.type().returnType(), 
+                                                                      target.type().returnType(),
-                                                                      generic.type().returnType(),
+                                                                      target.type().parameterType(0)));
-                                                                      generic.type().parameterType(0)));
         // drop the RHS parameter
-        cast = MethodHandles.dropArguments(cast, 2, generic.type().parameterType(1));
+        cast = MethodHandles.dropArguments(cast, 2, target.type().parameterType(1));
         // combine: f(x,y) -> g(f(x,y), x, y);
-        return MethodHandles.foldArguments(cast, generic);
+        return MethodHandles.foldArguments(cast, target);
+    }
+    
+    /** Looks up generic method, with a dynamic cast to the specified type. (explicit assignment) */
+    public static MethodHandle dynamicCast(MethodHandle target, Class<?> desired) {
+        // adapt dynamic cast to the generic method
+        desired = MethodType.methodType(desired).wrap().returnType();
+        // bind to the boxed type
+        MethodHandle cast = DYNAMIC_CAST.bindTo(desired);
+        return MethodHandles.filterReturnValue(target, cast);
     }
     
     /** Forces a cast to class A for target (only if types differ) */
@@ -1221,12 +1225,18 @@ public class DefMath {
         MethodType newType = MethodType.methodType(classA).unwrap();
         MethodType targetType = MethodType.methodType(target.type().returnType()).unwrap();
         
+        // don't do a conversion if types are the same. explicitCastArguments has this opto,
+        // but we do it explicitly, to make the boolean check simpler
         if (newType.returnType() == targetType.returnType()) {
-            return target; // no conversion
+            return target;
         }
         
-        // this is safe for our uses of it here only, because we change just the return value,
+        // we don't allow the to/from boolean conversions of explicitCastArguments
-        // the original method itself does all the type checks correctly.
+        if (newType.returnType() == boolean.class || targetType.returnType() == boolean.class) {
+            throw new ClassCastException("Cannot cast " + targetType.returnType() + " to " + newType.returnType());
+        }
+        
+        // null return values are not possible for our arguments.
         return MethodHandles.explicitCastArguments(target, target.type().changeReturnType(newType.returnType()));
     }
 }

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

@@ -30,6 +30,7 @@ import org.objectweb.asm.commons.Method;
 
 import java.util.ArrayDeque;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.BitSet;
 import java.util.Deque;
 import java.util.List;
@@ -78,15 +79,17 @@ import static org.elasticsearch.painless.WriterConstants.UTILITY_TYPE;
  */
 public final class MethodWriter extends GeneratorAdapter {
     private final BitSet statements;
+    private final CompilerSettings settings;
 
     private final Deque<List<org.objectweb.asm.Type>> stringConcatArgs =
         (INDY_STRING_CONCAT_BOOTSTRAP_HANDLE == null) ?  null : new ArrayDeque<>();
 
-    public MethodWriter(int access, Method method, ClassVisitor cw, BitSet statements) {
+    public MethodWriter(int access, Method method, ClassVisitor cw, BitSet statements, CompilerSettings settings) {
         super(Opcodes.ASM5, cw.visitMethod(access, method.getName(), method.getDescriptor(), null, null),
                 access, method.getName(), method.getDescriptor());
 
         this.statements = statements;
+        this.settings = settings;
     }
 
     /**
@@ -269,23 +272,18 @@ public final class MethodWriter extends GeneratorAdapter {
 
     /** Writes a dynamic binary instruction: returnType, lhs, and rhs can be different */
     public void writeDynamicBinaryInstruction(Location location, Type returnType, Type lhs, Type rhs, 
-                                              Operation operation, boolean compoundAssignment) {
+                                              Operation operation, int flags) {
         org.objectweb.asm.Type methodType = org.objectweb.asm.Type.getMethodType(returnType.type, lhs.type, rhs.type);
-        String descriptor = methodType.getDescriptor();
         
-        int flags = 0;
-        if (compoundAssignment) {
-            flags |= DefBootstrap.OPERATOR_COMPOUND_ASSIGNMENT;
-        }
         switch (operation) {
             case MUL:
-                invokeDynamic("mul", descriptor, DEF_BOOTSTRAP_HANDLE, DefBootstrap.BINARY_OPERATOR, flags); 
+                invokeDefCall("mul", methodType, DefBootstrap.BINARY_OPERATOR, flags); 
                 break;
             case DIV:
-                invokeDynamic("div", descriptor, DEF_BOOTSTRAP_HANDLE, DefBootstrap.BINARY_OPERATOR, flags); 
+                invokeDefCall("div", methodType, DefBootstrap.BINARY_OPERATOR, flags); 
                 break;
             case REM:
-                invokeDynamic("rem", descriptor, DEF_BOOTSTRAP_HANDLE, DefBootstrap.BINARY_OPERATOR, flags); 
+                invokeDefCall("rem", methodType, DefBootstrap.BINARY_OPERATOR, flags); 
                 break;
             case ADD:
                 // if either side is primitive, then the + operator should always throw NPE on null,
@@ -295,28 +293,28 @@ public final class MethodWriter extends GeneratorAdapter {
                 if (!hasPrimitiveArg) {
                     flags |= DefBootstrap.OPERATOR_ALLOWS_NULL;
                 }
-                invokeDynamic("add", descriptor, DEF_BOOTSTRAP_HANDLE, DefBootstrap.BINARY_OPERATOR, flags);
+                invokeDefCall("add", methodType, DefBootstrap.BINARY_OPERATOR, flags);
                 break;
             case SUB:
-                invokeDynamic("sub", descriptor, DEF_BOOTSTRAP_HANDLE, DefBootstrap.BINARY_OPERATOR, flags); 
+                invokeDefCall("sub", methodType, DefBootstrap.BINARY_OPERATOR, flags); 
                 break;
             case LSH:
-                invokeDynamic("lsh", descriptor, DEF_BOOTSTRAP_HANDLE, DefBootstrap.SHIFT_OPERATOR, flags);
+                invokeDefCall("lsh", methodType, DefBootstrap.SHIFT_OPERATOR, flags);
                 break;
             case USH:
-                invokeDynamic("ush", descriptor, DEF_BOOTSTRAP_HANDLE, DefBootstrap.SHIFT_OPERATOR, flags); 
+                invokeDefCall("ush", methodType, DefBootstrap.SHIFT_OPERATOR, flags); 
                 break;
             case RSH:
-                invokeDynamic("rsh", descriptor, DEF_BOOTSTRAP_HANDLE, DefBootstrap.SHIFT_OPERATOR, flags); 
+                invokeDefCall("rsh", methodType, DefBootstrap.SHIFT_OPERATOR, flags); 
                 break;
             case BWAND: 
-                invokeDynamic("and", descriptor, DEF_BOOTSTRAP_HANDLE, DefBootstrap.BINARY_OPERATOR, flags);
+                invokeDefCall("and", methodType, DefBootstrap.BINARY_OPERATOR, flags);
                 break;
             case XOR:   
-                invokeDynamic("xor", descriptor, DEF_BOOTSTRAP_HANDLE, DefBootstrap.BINARY_OPERATOR, flags);
+                invokeDefCall("xor", methodType, DefBootstrap.BINARY_OPERATOR, flags);
                 break;
             case BWOR:  
-                invokeDynamic("or", descriptor, DEF_BOOTSTRAP_HANDLE, DefBootstrap.BINARY_OPERATOR, flags);
+                invokeDefCall("or", methodType, DefBootstrap.BINARY_OPERATOR, flags);
                 break;
             default:
                 throw location.createError(new IllegalStateException("Illegal tree structure."));
@@ -391,4 +389,19 @@ public final class MethodWriter extends GeneratorAdapter {
     public void visitEnd() {
         throw new AssertionError("Should never call this method on MethodWriter, use endMethod() instead");
     }
+
+    /**
+     * Writes a dynamic call for a def method.
+     * @param name method name
+     * @param methodType callsite signature
+     * @param flavor type of call
+     * @param params flavor-specific parameters
+     */
+    public void invokeDefCall(String name, org.objectweb.asm.Type methodType, int flavor, Object... params) {
+        Object[] args = new Object[params.length + 2];
+        args[0] = settings.getInitialCallSiteDepth();
+        args[1] = flavor;
+        System.arraycopy(params, 0, args, 2, params.length);
+        invokeDynamic(name, methodType.getDescriptor(), DEF_BOOTSTRAP_HANDLE, args);
+    }
 }

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

@@ -128,6 +128,12 @@ public final class PainlessScriptEngineService extends AbstractComponent impleme
                 compilerSettings.setPicky(Boolean.parseBoolean(value));
             }
             
+            value = copy.remove(CompilerSettings.INITIAL_CALL_SITE_DEPTH);
+            
+            if (value != null) {
+                compilerSettings.setInitialCallSiteDepth(Integer.parseInt(value));
+            }
+
             if (!copy.isEmpty()) {
                 throw new IllegalArgumentException("Unrecognized compile-time parameter(s): " + copy);
             }

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

@@ -85,9 +85,10 @@ public final class WriterConstants {
     public final static Method MATCHER_FIND = getAsmMethod(boolean.class, "find");
 
     /** dynamic callsite bootstrap signature */
-    public final static MethodType DEF_BOOTSTRAP_TYPE =
+    final static MethodType DEF_BOOTSTRAP_TYPE =
-        MethodType.methodType(CallSite.class, MethodHandles.Lookup.class, String.class, MethodType.class, int.class, Object[].class);
+        MethodType.methodType(CallSite.class, MethodHandles.Lookup.class, String.class, MethodType.class, 
-    public final static Handle DEF_BOOTSTRAP_HANDLE =
+                              int.class, int.class, Object[].class);
+    final static Handle DEF_BOOTSTRAP_HANDLE =
         new Handle(Opcodes.H_INVOKESTATIC, Type.getInternalName(DefBootstrap.class),
             "bootstrap", DEF_BOOTSTRAP_TYPE.toMethodDescriptorString(), false);
 

modules/lang-painless/src/main/java/org/elasticsearch/painless/antlr/Walker.java

@@ -241,7 +241,7 @@ public final class Walker extends PainlessParserBaseVisitor<Object> {
             statements.add((AStatement)visit(statement));
         }
 
-        return new SSource(sourceName, sourceText, debugStream, (MainMethodReserved)reserved.pop(), 
+        return new SSource(settings, sourceName, sourceText, debugStream, (MainMethodReserved)reserved.pop(), 
                            location(ctx), functions, globals, statements);
     }
 

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

@@ -20,6 +20,7 @@
 package org.elasticsearch.painless.node;
 
 import org.elasticsearch.painless.AnalyzerCaster;
+import org.elasticsearch.painless.DefBootstrap;
 import org.elasticsearch.painless.Definition;
 import org.elasticsearch.painless.Globals;
 import org.elasticsearch.painless.Definition.Sort;
@@ -46,6 +47,7 @@ public final class EBinary extends AExpression {
     Type shiftDistance; // for shifts, the RHS is promoted independently
 
     boolean cat = false;
+    boolean originallyExplicit = false; // record whether there was originally an explicit cast
 
     public EBinary(Location location, Operation operation, AExpression left, AExpression right) {
         super(location);
@@ -63,6 +65,7 @@ public final class EBinary extends AExpression {
 
     @Override
     void analyze(Locals locals) {
+        originallyExplicit = explicit;
         if (operation == Operation.MUL) {
             analyzeMul(locals);
         } else if (operation == Operation.DIV) {
@@ -649,7 +652,13 @@ public final class EBinary extends AExpression {
             right.write(writer, globals);
 
             if (promote.sort == Sort.DEF || (shiftDistance != null && shiftDistance.sort == Sort.DEF)) {
-                writer.writeDynamicBinaryInstruction(location, actual, left.actual, right.actual, operation, false);
+                // def calls adopt the wanted return value. if there was a narrowing cast,
+                // we need to flag that so that its done at runtime.
+                int flags = 0;
+                if (originallyExplicit) {
+                    flags |= DefBootstrap.OPERATOR_EXPLICIT_CAST;
+                }
+                writer.writeDynamicBinaryInstruction(location, actual, left.actual, right.actual, operation, flags);
             } else {
                 writer.writeBinaryInstruction(location, actual, operation);
             }

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

@@ -30,7 +30,6 @@ import org.elasticsearch.painless.Locals.Variable;
 import org.objectweb.asm.Opcodes;
 import org.objectweb.asm.Type;
 
-import static org.elasticsearch.painless.WriterConstants.DEF_BOOTSTRAP_HANDLE;
 import static org.elasticsearch.painless.WriterConstants.LAMBDA_BOOTSTRAP_HANDLE;
 
 import java.lang.invoke.LambdaMetafactory;
@@ -97,8 +96,8 @@ public class ECapturingFunctionRef extends AExpression implements ILambda {
         } else if (ref == null) {
             // typed interface, dynamic implementation
             writer.visitVarInsn(captured.type.type.getOpcode(Opcodes.ILOAD), captured.getSlot());
-            String descriptor = Type.getMethodType(expected.type, captured.type.type).getDescriptor();
+            Type methodType = Type.getMethodType(expected.type, captured.type.type);
-            writer.invokeDynamic(call, descriptor, DEF_BOOTSTRAP_HANDLE, DefBootstrap.REFERENCE, expected.name);
+            writer.invokeDefCall(call, methodType, DefBootstrap.REFERENCE, expected.name);
         } else {
             // typed interface, typed implementation
             writer.visitVarInsn(captured.type.type.getOpcode(Opcodes.ILOAD), captured.getSlot());

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

@@ -26,6 +26,7 @@ import org.elasticsearch.painless.Definition.Sort;
 import org.elasticsearch.painless.Definition.Type;
 import org.elasticsearch.painless.Location;
 import org.elasticsearch.painless.AnalyzerCaster;
+import org.elasticsearch.painless.DefBootstrap;
 import org.elasticsearch.painless.Operation;
 import org.elasticsearch.painless.Locals;
 import org.elasticsearch.painless.MethodWriter;
@@ -226,7 +227,10 @@ public final class EChain extends AExpression {
 
             expression.expected = expression.actual;
         } else if (shift) {
-            if (shiftDistance.sort == Sort.LONG) {
+            if (promote.sort == Sort.DEF) {
+                // shifts are promoted independently, but for the def type, we need object.
+                expression.expected = promote;
+            } else if (shiftDistance.sort == Sort.LONG) {
                 expression.expected = Definition.INT_TYPE;
                 expression.explicit = true;   
             } else {
@@ -365,7 +369,7 @@ public final class EChain extends AExpression {
                     // write the operation instruction for compound assignment
                     if (promote.sort == Sort.DEF) {
                         writer.writeDynamicBinaryInstruction(location, promote, 
-                            Definition.DEF_TYPE, Definition.DEF_TYPE, operation, true);
+                            Definition.DEF_TYPE, Definition.DEF_TYPE, operation, DefBootstrap.OPERATOR_COMPOUND_ASSIGNMENT);
                     } else {
                         writer.writeBinaryInstruction(location, promote, operation);
                     }

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

@@ -37,7 +37,6 @@ import org.elasticsearch.painless.MethodWriter;
 
 import static org.elasticsearch.painless.WriterConstants.OBJECTS_TYPE;
 import static org.elasticsearch.painless.WriterConstants.EQUALS;
-import static org.elasticsearch.painless.WriterConstants.DEF_BOOTSTRAP_HANDLE;
 
 /**
  * Represents a comparison expression.
@@ -508,8 +507,7 @@ public final class EComp extends AExpression {
                     if (right.isNull) {
                         writer.ifNull(jump);
                     } else if (!left.isNull && (operation == Operation.EQ || operation == Operation.NE)) {
-                        writer.invokeDynamic("eq", descriptor.getDescriptor(), DEF_BOOTSTRAP_HANDLE, DefBootstrap.BINARY_OPERATOR,
+                        writer.invokeDefCall("eq", descriptor, DefBootstrap.BINARY_OPERATOR, DefBootstrap.OPERATOR_ALLOWS_NULL);
-                                                                                                     DefBootstrap.OPERATOR_ALLOWS_NULL);
                         writejump = false;
                     } else {
                         writer.ifCmp(promotedType.type, MethodWriter.EQ, jump);
@@ -518,23 +516,22 @@ public final class EComp extends AExpression {
                     if (right.isNull) {
                         writer.ifNonNull(jump);
                     } else if (!left.isNull && (operation == Operation.EQ || operation == Operation.NE)) {
-                        writer.invokeDynamic("eq", descriptor.getDescriptor(), DEF_BOOTSTRAP_HANDLE, DefBootstrap.BINARY_OPERATOR,
+                        writer.invokeDefCall("eq", descriptor, DefBootstrap.BINARY_OPERATOR, DefBootstrap.OPERATOR_ALLOWS_NULL);
-                                                                                                     DefBootstrap.OPERATOR_ALLOWS_NULL);
                         writer.ifZCmp(MethodWriter.EQ, jump);
                     } else {
                         writer.ifCmp(promotedType.type, MethodWriter.NE, jump);
                     }
                 } else if (lt) {
-                    writer.invokeDynamic("lt", descriptor.getDescriptor(), DEF_BOOTSTRAP_HANDLE, DefBootstrap.BINARY_OPERATOR, 0);
+                    writer.invokeDefCall("lt", descriptor, DefBootstrap.BINARY_OPERATOR, 0);
                     writejump = false;
                 } else if (lte) {
-                    writer.invokeDynamic("lte", descriptor.getDescriptor(), DEF_BOOTSTRAP_HANDLE, DefBootstrap.BINARY_OPERATOR, 0);
+                    writer.invokeDefCall("lte", descriptor, DefBootstrap.BINARY_OPERATOR, 0);
                     writejump = false;
                 } else if (gt) {
-                    writer.invokeDynamic("gt", descriptor.getDescriptor(), DEF_BOOTSTRAP_HANDLE, DefBootstrap.BINARY_OPERATOR, 0);
+                    writer.invokeDefCall("gt", descriptor, DefBootstrap.BINARY_OPERATOR, 0);
                     writejump = false;
                 } else if (gte) {
-                    writer.invokeDynamic("gte", descriptor.getDescriptor(), DEF_BOOTSTRAP_HANDLE, DefBootstrap.BINARY_OPERATOR, 0);
+                    writer.invokeDefCall("gte", descriptor, DefBootstrap.BINARY_OPERATOR, 0);
                     writejump = false;
                 } else {
                     throw createError(new IllegalStateException("Illegal tree structure."));

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

@@ -35,8 +35,6 @@ import java.util.Set;
 
 import org.elasticsearch.painless.MethodWriter;
 
-import static org.elasticsearch.painless.WriterConstants.DEF_BOOTSTRAP_HANDLE;
-
 /**
  * Represents a unary math expression.
  */
@@ -45,6 +43,7 @@ public final class EUnary extends AExpression {
     final Operation operation;
     AExpression child;
     Type promote;
+    boolean originallyExplicit = false; // record whether there was originally an explicit cast
 
     public EUnary(Location location, Operation operation, AExpression child) {
         super(location);
@@ -60,6 +59,7 @@ public final class EUnary extends AExpression {
 
     @Override
     void analyze(Locals locals) {
+        originallyExplicit = explicit;
         if (operation == Operation.NOT) {
             analyzeNot(locals);
         } else if (operation == Operation.BWNOT) {
@@ -212,10 +212,16 @@ public final class EUnary extends AExpression {
             Sort sort = promote.sort;
             child.write(writer, globals);
 
+            // def calls adopt the wanted return value. if there was a narrowing cast,
+            // we need to flag that so that its done at runtime.
+            int defFlags = 0;
+            if (originallyExplicit) {
+                defFlags |= DefBootstrap.OPERATOR_EXPLICIT_CAST;
+            }
             if (operation == Operation.BWNOT) {
                 if (sort == Sort.DEF) {
                     org.objectweb.asm.Type descriptor = org.objectweb.asm.Type.getMethodType(actual.type, child.actual.type);
-                    writer.invokeDynamic("not", descriptor.getDescriptor(), DEF_BOOTSTRAP_HANDLE, DefBootstrap.UNARY_OPERATOR, 0);
+                    writer.invokeDefCall("not", descriptor, DefBootstrap.UNARY_OPERATOR, defFlags);
                 } else {
                     if (sort == Sort.INT) {
                         writer.push(-1);
@@ -230,14 +236,14 @@ public final class EUnary extends AExpression {
             } else if (operation == Operation.SUB) {
                 if (sort == Sort.DEF) {
                     org.objectweb.asm.Type descriptor = org.objectweb.asm.Type.getMethodType(actual.type, child.actual.type);
-                    writer.invokeDynamic("neg", descriptor.getDescriptor(), DEF_BOOTSTRAP_HANDLE, DefBootstrap.UNARY_OPERATOR, 0);
+                    writer.invokeDefCall("neg", descriptor, DefBootstrap.UNARY_OPERATOR, defFlags);
                 } else {
                     writer.math(MethodWriter.NEG, actual.type);
                 }
             } else if (operation == Operation.ADD) {
                 if (sort == Sort.DEF) {
                     org.objectweb.asm.Type descriptor = org.objectweb.asm.Type.getMethodType(actual.type, child.actual.type);
-                    writer.invokeDynamic("plus", descriptor.getDescriptor(), DEF_BOOTSTRAP_HANDLE, DefBootstrap.UNARY_OPERATOR, 0);
+                    writer.invokeDefCall("plus", descriptor, DefBootstrap.UNARY_OPERATOR, defFlags);
                 } 
             } else {
                 throw createError(new IllegalStateException("Illegal tree structure."));

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

@@ -31,8 +31,6 @@ import java.util.Set;
 
 import org.elasticsearch.painless.MethodWriter;
 
-import static org.elasticsearch.painless.WriterConstants.DEF_BOOTSTRAP_HANDLE;
-
 /**
  * Represents an array load/store or shortcut on a def type.  (Internal only.)
  */
@@ -71,15 +69,15 @@ final class LDefArray extends ALink implements IDefLink {
     void load(MethodWriter writer, Globals globals) {
         writer.writeDebugInfo(location);
 
-        String desc = Type.getMethodDescriptor(after.type, Definition.DEF_TYPE.type, index.actual.type);
+        Type methodType = Type.getMethodType(after.type, Definition.DEF_TYPE.type, index.actual.type);
-        writer.invokeDynamic("arrayLoad", desc, DEF_BOOTSTRAP_HANDLE, DefBootstrap.ARRAY_LOAD);
+        writer.invokeDefCall("arrayLoad", methodType, DefBootstrap.ARRAY_LOAD);
     }
 
     @Override
     void store(MethodWriter writer, Globals globals) {
         writer.writeDebugInfo(location);
 
-        String desc = Type.getMethodDescriptor(Definition.VOID_TYPE.type, Definition.DEF_TYPE.type, index.actual.type, after.type);
+        Type methodType = Type.getMethodType(Definition.VOID_TYPE.type, Definition.DEF_TYPE.type, index.actual.type, after.type);
-        writer.invokeDynamic("arrayStore", desc, DEF_BOOTSTRAP_HANDLE, DefBootstrap.ARRAY_STORE);
+        writer.invokeDefCall("arrayStore", methodType, DefBootstrap.ARRAY_STORE);
     }
 }

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

@@ -32,8 +32,6 @@ import java.util.List;
 import java.util.Objects;
 import java.util.Set;
 
-import static org.elasticsearch.painless.WriterConstants.DEF_BOOTSTRAP_HANDLE;
-
 /**
  * Represents a method call made on a def type. (Internal only.)
  */
@@ -96,32 +94,30 @@ final class LDefCall extends ALink implements IDefLink {
     void load(MethodWriter writer, Globals globals) {
         writer.writeDebugInfo(location);
 
-        StringBuilder signature = new StringBuilder();
+        List<Type> parameterTypes = new ArrayList<>();
 
-        signature.append('(');
         // first parameter is the receiver, we never know its type: always Object
-        signature.append(Definition.DEF_TYPE.type.getDescriptor());
+        parameterTypes.add(Definition.DEF_TYPE.type);
 
+        // append each argument
         for (AExpression argument : arguments) {
-            signature.append(argument.actual.type.getDescriptor());
+            parameterTypes.add(argument.actual.type);
             if (argument instanceof ILambda) {
                 ILambda lambda = (ILambda) argument;
                 for (Type capture : lambda.getCaptures()) {
-                    signature.append(capture.getDescriptor());
+                    parameterTypes.add(capture);
                 }
             }
             argument.write(writer, globals);
         }
 
-        signature.append(')');
+        // create method type from return value and arguments
-        // return value
+        Type methodType = Type.getMethodType(after.type, parameterTypes.toArray(new Type[0]));
-        signature.append(after.type.getDescriptor());
 
         List<Object> args = new ArrayList<>();
-        args.add(DefBootstrap.METHOD_CALL);
         args.add(recipe.toString());
         args.addAll(pointers);
-        writer.invokeDynamic(name, signature.toString(), DEF_BOOTSTRAP_HANDLE, args.toArray());
+        writer.invokeDefCall(name, methodType, DefBootstrap.METHOD_CALL, args.toArray());
     }
 
     @Override

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

@@ -31,8 +31,6 @@ import java.util.Set;
 
 import org.elasticsearch.painless.MethodWriter;
 
-import static org.elasticsearch.painless.WriterConstants.DEF_BOOTSTRAP_HANDLE;
-
 /**
  * Represents a field load/store or shortcut on a def type.  (Internal only.)
  */
@@ -65,15 +63,15 @@ final class LDefField extends ALink implements IDefLink {
     void load(MethodWriter writer, Globals globals) {
         writer.writeDebugInfo(location);
 
-        String desc = Type.getMethodDescriptor(after.type, Definition.DEF_TYPE.type);
+        Type methodType = Type.getMethodType(after.type, Definition.DEF_TYPE.type);
-        writer.invokeDynamic(value, desc, DEF_BOOTSTRAP_HANDLE, DefBootstrap.LOAD);
+        writer.invokeDefCall(value, methodType, DefBootstrap.LOAD);
     }
 
     @Override
     void store(MethodWriter writer, Globals globals) {
         writer.writeDebugInfo(location);
 
-        String desc = Type.getMethodDescriptor(Definition.VOID_TYPE.type, Definition.DEF_TYPE.type, after.type);
+        Type methodType = Type.getMethodType(Definition.VOID_TYPE.type, Definition.DEF_TYPE.type, after.type);
-        writer.invokeDynamic(value, desc, DEF_BOOTSTRAP_HANDLE, DefBootstrap.STORE);
+        writer.invokeDefCall(value, methodType, DefBootstrap.STORE);
     }
 }

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

@@ -38,7 +38,6 @@ import org.objectweb.asm.Opcodes;
 import java.util.Objects;
 import java.util.Set;
 
-import static org.elasticsearch.painless.WriterConstants.DEF_BOOTSTRAP_HANDLE;
 import static org.elasticsearch.painless.WriterConstants.ITERATOR_HASNEXT;
 import static org.elasticsearch.painless.WriterConstants.ITERATOR_NEXT;
 import static org.elasticsearch.painless.WriterConstants.ITERATOR_TYPE;
@@ -205,8 +204,8 @@ public class SEach extends AStatement {
 
         if (method == null) {
             Type itr = Definition.getType("Iterator");
-            String desc = org.objectweb.asm.Type.getMethodDescriptor(itr.type, Definition.DEF_TYPE.type);
+            org.objectweb.asm.Type methodType = org.objectweb.asm.Type.getMethodType(itr.type, Definition.DEF_TYPE.type);
-            writer.invokeDynamic("iterator", desc, DEF_BOOTSTRAP_HANDLE, DefBootstrap.ITERATOR);
+            writer.invokeDefCall("iterator", methodType, DefBootstrap.ITERATOR);
         } else if (java.lang.reflect.Modifier.isInterface(method.owner.clazz.getModifiers())) {
             writer.invokeInterface(method.owner.type, method.method);
         } else {

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

@@ -19,6 +19,7 @@
 
 package org.elasticsearch.painless.node;
 
+import org.elasticsearch.painless.CompilerSettings;
 import org.elasticsearch.painless.Constant;
 import org.elasticsearch.painless.Def;
 import org.elasticsearch.painless.Definition;
@@ -151,12 +152,12 @@ public class SFunction extends AStatement {
     }
     
     /** Writes the function to given ClassVisitor. */
-    void write (ClassVisitor writer, Globals globals) {
+    void write (ClassVisitor writer, CompilerSettings settings, Globals globals) {
         int access = Opcodes.ACC_PRIVATE | Opcodes.ACC_STATIC;
         if (synthetic) {
             access |= Opcodes.ACC_SYNTHETIC;
         }
-        final MethodWriter function = new MethodWriter(access, method.method, writer, globals.getStatements());
+        final MethodWriter function = new MethodWriter(access, method.method, writer, globals.getStatements(), settings);
         write(function, globals);
         function.endMethod();
     }

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

@@ -19,6 +19,7 @@
 
 package org.elasticsearch.painless.node;
 
+import org.elasticsearch.painless.CompilerSettings;
 import org.elasticsearch.painless.Constant;
 import org.elasticsearch.painless.Definition.Method;
 import org.elasticsearch.painless.Definition.MethodKey;
@@ -61,6 +62,7 @@ public final class SSource extends AStatement {
     final String name;
     final String source;
     final Printer debugStream;
+    final CompilerSettings settings;
     final MainMethodReserved reserved;
     final List<SFunction> functions;
     final Globals globals;
@@ -69,10 +71,11 @@ public final class SSource extends AStatement {
     private Locals mainMethod;
     private byte[] bytes;
 
-    public SSource(String name, String source, Printer debugStream, MainMethodReserved reserved, Location location, 
+    public SSource(CompilerSettings settings, String name, String source, Printer debugStream, 
+                   MainMethodReserved reserved, Location location, 
                    List<SFunction> functions, Globals globals, List<AStatement> statements) {
         super(location);
-
+        this.settings = Objects.requireNonNull(settings);
         this.name = Objects.requireNonNull(name);
         this.source = Objects.requireNonNull(source);
         this.debugStream = debugStream;
@@ -159,7 +162,7 @@ public final class SSource extends AStatement {
         visitor.visitSource(Location.computeSourceName(name, source), null);
 
         // Write the constructor:
-        MethodWriter constructor = new MethodWriter(Opcodes.ACC_PUBLIC, CONSTRUCTOR, visitor, globals.getStatements());
+        MethodWriter constructor = new MethodWriter(Opcodes.ACC_PUBLIC, CONSTRUCTOR, visitor, globals.getStatements(), settings);
         constructor.visitCode();
         constructor.loadThis();
         constructor.loadArgs();
@@ -168,14 +171,14 @@ public final class SSource extends AStatement {
         constructor.endMethod();
 
         // Write the execute method:
-        MethodWriter execute = new MethodWriter(Opcodes.ACC_PUBLIC, EXECUTE, visitor, globals.getStatements());
+        MethodWriter execute = new MethodWriter(Opcodes.ACC_PUBLIC, EXECUTE, visitor, globals.getStatements(), settings);
         execute.visitCode();
         write(execute, globals);
         execute.endMethod();
         
         // Write all functions:
         for (SFunction function : functions) {
-            function.write(visitor, globals);
+            function.write(visitor, settings, globals);
         }
         
         // Write all synthetic functions. Note that this process may add more :)
@@ -183,7 +186,7 @@ public final class SSource extends AStatement {
             List<SFunction> current = new ArrayList<>(globals.getSyntheticMethods().values());
             globals.getSyntheticMethods().clear();
             for (SFunction function : current) {
-                function.write(visitor, globals);
+                function.write(visitor, settings, globals);
             }
         }
 
@@ -203,7 +206,7 @@ public final class SSource extends AStatement {
 
             // Initialize the constants in a static initializer
             final MethodWriter clinit = new MethodWriter(Opcodes.ACC_STATIC, 
-                    WriterConstants.CLINIT, visitor, globals.getStatements());
+                    WriterConstants.CLINIT, visitor, globals.getStatements(), settings);
             for (Constant constant : inits) {
                 constant.initializer.accept(clinit);
                 clinit.putStatic(CLASS_TYPE, constant.name, constant.type);

modules/lang-painless/src/test/java/org/elasticsearch/painless/CastTests.java

@@ -0,0 +1,307 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.painless;
+
+/** Tests for explicit casts */
+public class CastTests extends ScriptTestCase {
+    
+    /**
+     * Unary operator with explicit cast
+     */
+    public void testUnaryOperator() {
+        assertEquals((byte)5, exec("long x = 5L; return (byte) (+x);"));
+        assertEquals((short)5, exec("long x = 5L; return (short) (+x);"));
+        assertEquals((char)5, exec("long x = 5L; return (char) (+x);"));
+        assertEquals(5, exec("long x = 5L; return (int) (+x);"));
+        assertEquals(5F, exec("long x = 5L; return (float) (+x);"));
+        assertEquals(5L, exec("long x = 5L; return (long) (+x);"));
+        assertEquals(5D, exec("long x = 5L; return (double) (+x);"));
+    }
+    
+    /**
+     * Binary operators with explicit cast
+     */
+    public void testBinaryOperator() {
+        assertEquals((byte)6, exec("long x = 5L; return (byte) (x + 1);"));
+        assertEquals((short)6, exec("long x = 5L; return (short) (x + 1);"));
+        assertEquals((char)6, exec("long x = 5L; return (char) (x + 1);"));
+        assertEquals(6, exec("long x = 5L; return (int) (x + 1);"));
+        assertEquals(6F, exec("long x = 5L; return (float) (x + 1);"));
+        assertEquals(6L, exec("long x = 5L; return (long) (x + 1);"));
+        assertEquals(6D, exec("long x = 5L; return (double) (x + 1);"));
+    }
+
+    /**
+     * Binary compound assignment with explicit cast
+     */
+    public void testBinaryCompoundAssignment() {
+        assertEquals((byte)6, exec("long x = 5L; return (byte) (x += 1);"));
+        assertEquals((short)6, exec("long x = 5L; return (short) (x += 1);"));
+        assertEquals((char)6, exec("long x = 5L; return (char) (x += 1);"));
+        assertEquals(6, exec("long x = 5L; return (int) (x += 1);"));
+        assertEquals(6F, exec("long x = 5L; return (float) (x += 1);"));
+        assertEquals(6L, exec("long x = 5L; return (long) (x += 1);"));
+        assertEquals(6D, exec("long x = 5L; return (double) (x += 1);"));
+    }
+
+    /**
+     * Binary compound prefix with explicit cast
+     */
+    public void testBinaryPrefix() {
+        assertEquals((byte)6, exec("long x = 5L; return (byte) (++x);"));
+        assertEquals((short)6, exec("long x = 5L; return (short) (++x);"));
+        assertEquals((char)6, exec("long x = 5L; return (char) (++x);"));
+        assertEquals(6, exec("long x = 5L; return (int) (++x);"));
+        assertEquals(6F, exec("long x = 5L; return (float) (++x);"));
+        assertEquals(6L, exec("long x = 5L; return (long) (++x);"));
+        assertEquals(6D, exec("long x = 5L; return (double) (++x);"));
+    }
+    
+    /**
+     * Binary compound postifx with explicit cast
+     */
+    public void testBinaryPostfix() {
+        assertEquals((byte)5, exec("long x = 5L; return (byte) (x++);"));
+        assertEquals((short)5, exec("long x = 5L; return (short) (x++);"));
+        assertEquals((char)5, exec("long x = 5L; return (char) (x++);"));
+        assertEquals(5, exec("long x = 5L; return (int) (x++);"));
+        assertEquals(5F, exec("long x = 5L; return (float) (x++);"));
+        assertEquals(5L, exec("long x = 5L; return (long) (x++);"));
+        assertEquals(5D, exec("long x = 5L; return (double) (x++);"));
+    }
+    
+    /**
+     * Shift operators with explicit cast
+     */
+    public void testShiftOperator() {
+        assertEquals((byte)10, exec("long x = 5L; return (byte) (x << 1);"));
+        assertEquals((short)10, exec("long x = 5L; return (short) (x << 1);"));
+        assertEquals((char)10, exec("long x = 5L; return (char) (x << 1);"));
+        assertEquals(10, exec("long x = 5L; return (int) (x << 1);"));
+        assertEquals(10F, exec("long x = 5L; return (float) (x << 1);"));
+        assertEquals(10L, exec("long x = 5L; return (long) (x << 1);"));
+        assertEquals(10D, exec("long x = 5L; return (double) (x << 1);"));
+    }
+    
+    /**
+     * Shift compound assignment with explicit cast
+     */
+    public void testShiftCompoundAssignment() {
+        assertEquals((byte)10, exec("long x = 5L; return (byte) (x <<= 1);"));
+        assertEquals((short)10, exec("long x = 5L; return (short) (x <<= 1);"));
+        assertEquals((char)10, exec("long x = 5L; return (char) (x <<= 1);"));
+        assertEquals(10, exec("long x = 5L; return (int) (x <<= 1);"));
+        assertEquals(10F, exec("long x = 5L; return (float) (x <<= 1);"));
+        assertEquals(10L, exec("long x = 5L; return (long) (x <<= 1);"));
+        assertEquals(10D, exec("long x = 5L; return (double) (x <<= 1);"));
+    }
+    
+    /**
+     * Test that without a cast, we fail when conversions would narrow.
+     */
+    public void testIllegalConversions() {
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("long x = 5L; int y = +x; return y");
+        });
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("long x = 5L; int y = (x + x); return y");
+        });
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("boolean x = true; int y = +x; return y");
+        });
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("boolean x = true; int y = (x ^ false); return y");
+        });
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("long x = 5L; boolean y = +x; return y");
+        });
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("long x = 5L; boolean y = (x + x); return y");
+        });
+    }
+    
+    /**
+     * Test that even with a cast, some things aren't allowed.
+     */
+    public void testIllegalExplicitConversions() {
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("boolean x = true; int y = (int) +x; return y");
+        });
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("boolean x = true; int y = (int) (x ^ false); return y");
+        });
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("long x = 5L; boolean y = (boolean) +x; return y");
+        });
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("long x = 5L; boolean y = (boolean) (x + x); return y");
+        });
+    }
+
+    /**
+     * Currently these do not adopt the return value, we issue a separate cast!
+     */
+    public void testMethodCallDef() {
+        assertEquals(5, exec("def x = 5; return (int)x.longValue();"));
+    }
+    
+    /**
+     * Currently these do not adopt the argument value, we issue a separate cast!
+     */
+    public void testArgumentsDef() {
+        assertEquals(5, exec("def x = 5L; return (+(int)x);"));
+        assertEquals(6, exec("def x = 5; def y = 1L; return x + (int)y"));
+        assertEquals('b', exec("def x = 'abcdeg'; def y = 1L; x.charAt((int)y)"));
+    }
+    
+    /**
+     * Unary operators adopt the return value
+     */
+    public void testUnaryOperatorDef() {
+        assertEquals((byte)5, exec("def x = 5L; return (byte) (+x);"));
+        assertEquals((short)5, exec("def x = 5L; return (short) (+x);"));
+        assertEquals((char)5, exec("def x = 5L; return (char) (+x);"));
+        assertEquals(5, exec("def x = 5L; return (int) (+x);"));
+        assertEquals(5F, exec("def x = 5L; return (float) (+x);"));
+        assertEquals(5L, exec("def x = 5L; return (long) (+x);"));
+        assertEquals(5D, exec("def x = 5L; return (double) (+x);"));
+    }
+    
+    /**
+     * Binary operators adopt the return value
+     */
+    public void testBinaryOperatorDef() {
+        assertEquals((byte)6, exec("def x = 5L; return (byte) (x + 1);"));
+        assertEquals((short)6, exec("def x = 5L; return (short) (x + 1);"));
+        assertEquals((char)6, exec("def x = 5L; return (char) (x + 1);"));
+        assertEquals(6, exec("def x = 5L; return (int) (x + 1);"));
+        assertEquals(6F, exec("def x = 5L; return (float) (x + 1);"));
+        assertEquals(6L, exec("def x = 5L; return (long) (x + 1);"));
+        assertEquals(6D, exec("def x = 5L; return (double) (x + 1);"));
+    }
+    
+    /**
+     * Binary operators don't yet adopt the return value with compound assignment
+     */
+    public void testBinaryCompoundAssignmentDef() {
+        assertEquals((byte)6, exec("def x = 5L; return (byte) (x += 1);"));
+        assertEquals((short)6, exec("def x = 5L; return (short) (x += 1);"));
+        assertEquals((char)6, exec("def x = 5L; return (char) (x += 1);"));
+        assertEquals(6, exec("def x = 5L; return (int) (x += 1);"));
+        assertEquals(6F, exec("def x = 5L; return (float) (x += 1);"));
+        assertEquals(6L, exec("def x = 5L; return (long) (x += 1);"));
+        assertEquals(6D, exec("def x = 5L; return (double) (x += 1);"));
+    }
+    
+    /**
+     * Binary operators don't yet adopt the return value with compound assignment
+     */
+    public void testBinaryCompoundAssignmentPrefix() {
+        assertEquals((byte)6, exec("def x = 5L; return (byte) (++x);"));
+        assertEquals((short)6, exec("def x = 5L; return (short) (++x);"));
+        assertEquals((char)6, exec("def x = 5L; return (char) (++x);"));
+        assertEquals(6, exec("def x = 5L; return (int) (++x);"));
+        assertEquals(6F, exec("def x = 5L; return (float) (++x);"));
+        assertEquals(6L, exec("def x = 5L; return (long) (++x);"));
+        assertEquals(6D, exec("def x = 5L; return (double) (++x);"));
+    }
+    
+    /**
+     * Binary operators don't yet adopt the return value with compound assignment
+     */
+    public void testBinaryCompoundAssignmentPostfix() {
+        assertEquals((byte)5, exec("def x = 5L; return (byte) (x++);"));
+        assertEquals((short)5, exec("def x = 5L; return (short) (x++);"));
+        assertEquals((char)5, exec("def x = 5L; return (char) (x++);"));
+        assertEquals(5, exec("def x = 5L; return (int) (x++);"));
+        assertEquals(5F, exec("def x = 5L; return (float) (x++);"));
+        assertEquals(5L, exec("def x = 5L; return (long) (x++);"));
+        assertEquals(5D, exec("def x = 5L; return (double) (x++);"));
+    }
+    
+    /**
+     * Shift operators adopt the return value
+     */
+    public void testShiftOperatorDef() {
+        assertEquals((byte)10, exec("def x = 5L; return (byte) (x << 1);"));
+        assertEquals((short)10, exec("def x = 5L; return (short) (x << 1);"));
+        assertEquals((char)10, exec("def x = 5L; return (char) (x << 1);"));
+        assertEquals(10, exec("def x = 5L; return (int) (x << 1);"));
+        assertEquals(10F, exec("def x = 5L; return (float) (x << 1);"));
+        assertEquals(10L, exec("def x = 5L; return (long) (x << 1);"));
+        assertEquals(10D, exec("def x = 5L; return (double) (x << 1);"));
+    }
+    
+    /**
+     * Shift operators don't yet adopt the return value with compound assignment
+     */
+    public void testShiftCompoundAssignmentDef() {
+        assertEquals((byte)10, exec("def x = 5L; return (byte) (x <<= 1);"));
+        assertEquals((short)10, exec("def x = 5L; return (short) (x <<= 1);"));
+        assertEquals((char)10, exec("def x = 5L; return (char) (x <<= 1);"));
+        assertEquals(10, exec("def x = 5L; return (int) (x <<= 1);"));
+        assertEquals(10F, exec("def x = 5L; return (float) (x <<= 1);"));
+        assertEquals(10L, exec("def x = 5L; return (long) (x <<= 1);"));
+        assertEquals(10D, exec("def x = 5L; return (double) (x <<= 1);"));
+    }
+    
+    /**
+     * Test that without a cast, we fail when conversions would narrow.
+     */
+    public void testIllegalConversionsDef() {
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("def x = 5L; int y = +x; return y");
+        });
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("def x = 5L; int y = (x + x); return y");
+        });
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("def x = true; int y = +x; return y");
+        });
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("def x = true; int y = (x ^ false); return y");
+        });
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("def x = 5L; boolean y = +x; return y");
+        });
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("def x = 5L; boolean y = (x + x); return y");
+        });
+    }
+    
+    /**
+     * Test that even with a cast, some things aren't allowed.
+     * (stuff that methodhandles explicitCastArguments would otherwise allow)
+     */
+    public void testIllegalExplicitConversionsDef() {
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("def x = true; int y = (int) +x; return y");
+        });
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("def x = true; int y = (int) (x ^ false); return y");
+        });
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("def x = 5L; boolean y = (boolean) +x; return y");
+        });
+        expectScriptThrows(ClassCastException.class, () -> {
+            exec("def x = 5L; boolean y = (boolean) (x + x); return y");
+        });
+    }
+}

modules/lang-painless/src/test/java/org/elasticsearch/painless/DefBootstrapTests.java

@@ -36,6 +36,7 @@ public class DefBootstrapTests extends ESTestCase {
         CallSite site = DefBootstrap.bootstrap(MethodHandles.publicLookup(), 
                                                   "toString", 
                                                   MethodType.methodType(String.class, Object.class), 
+                                                  0,
                                                   DefBootstrap.METHOD_CALL, "");
         MethodHandle handle = site.dynamicInvoker();
         assertDepthEquals(site, 0);
@@ -53,6 +54,7 @@ public class DefBootstrapTests extends ESTestCase {
         CallSite site = DefBootstrap.bootstrap(MethodHandles.publicLookup(), 
                                                   "toString", 
                                                   MethodType.methodType(String.class, Object.class), 
+                                                  0,
                                                   DefBootstrap.METHOD_CALL, "");
         MethodHandle handle = site.dynamicInvoker();
         assertDepthEquals(site, 0);
@@ -75,6 +77,7 @@ public class DefBootstrapTests extends ESTestCase {
         CallSite site = DefBootstrap.bootstrap(MethodHandles.publicLookup(), 
                                                   "toString", 
                                                   MethodType.methodType(String.class, Object.class), 
+                                                  0,
                                                   DefBootstrap.METHOD_CALL, "");
         MethodHandle handle = site.dynamicInvoker();
         assertDepthEquals(site, 0);
@@ -98,6 +101,7 @@ public class DefBootstrapTests extends ESTestCase {
         DefBootstrap.PIC site = (DefBootstrap.PIC) DefBootstrap.bootstrap(MethodHandles.publicLookup(), 
                                                                           "size", 
                                                                           MethodType.methodType(int.class, Object.class), 
+                                                                          0,
                                                                           DefBootstrap.METHOD_CALL, "");
         site.depth = DefBootstrap.PIC.MAX_DEPTH; // mark megamorphic
         MethodHandle handle = site.dynamicInvoker();
@@ -127,6 +131,7 @@ public class DefBootstrapTests extends ESTestCase {
         DefBootstrap.MIC site = (DefBootstrap.MIC) DefBootstrap.bootstrap(MethodHandles.publicLookup(), 
                                                                "add", 
                                                                MethodType.methodType(Object.class, Object.class, Object.class),
+                                                               0,
                                                                DefBootstrap.BINARY_OPERATOR, DefBootstrap.OPERATOR_ALLOWS_NULL);
         MethodHandle handle = site.dynamicInvoker();
         assertEquals("nulltest", (Object)handle.invokeExact((Object)null, (Object)"test"));
@@ -136,6 +141,7 @@ public class DefBootstrapTests extends ESTestCase {
         DefBootstrap.MIC site = (DefBootstrap.MIC) DefBootstrap.bootstrap(MethodHandles.publicLookup(), 
                                                                "add", 
                                                                MethodType.methodType(Object.class, Object.class, Object.class),
+                                                               0,
                                                                DefBootstrap.BINARY_OPERATOR, DefBootstrap.OPERATOR_ALLOWS_NULL);
         MethodHandle handle = site.dynamicInvoker();
         assertEquals(2, (Object)handle.invokeExact((Object)1, (Object)1));
@@ -146,6 +152,7 @@ public class DefBootstrapTests extends ESTestCase {
         DefBootstrap.MIC site = (DefBootstrap.MIC) DefBootstrap.bootstrap(MethodHandles.publicLookup(), 
                                                                "eq", 
                                                                MethodType.methodType(boolean.class, Object.class, Object.class),
+                                                               0,
                                                                DefBootstrap.BINARY_OPERATOR, DefBootstrap.OPERATOR_ALLOWS_NULL);
         MethodHandle handle = site.dynamicInvoker();
         assertFalse((boolean) handle.invokeExact((Object)null, (Object)"test"));
@@ -156,6 +163,7 @@ public class DefBootstrapTests extends ESTestCase {
         DefBootstrap.MIC site = (DefBootstrap.MIC) DefBootstrap.bootstrap(MethodHandles.publicLookup(), 
                                                                "eq", 
                                                                MethodType.methodType(boolean.class, Object.class, Object.class),
+                                                               0,
                                                                DefBootstrap.BINARY_OPERATOR, DefBootstrap.OPERATOR_ALLOWS_NULL);
         MethodHandle handle = site.dynamicInvoker();
         assertTrue((boolean) handle.invokeExact((Object)1, (Object)1));
@@ -171,6 +179,7 @@ public class DefBootstrapTests extends ESTestCase {
         DefBootstrap.MIC site = (DefBootstrap.MIC) DefBootstrap.bootstrap(MethodHandles.publicLookup(), 
                                                                "add", 
                                                                MethodType.methodType(Object.class, int.class, Object.class),
+                                                               0,
                                                                DefBootstrap.BINARY_OPERATOR, 0);
         MethodHandle handle = site.dynamicInvoker();
         expectThrows(NullPointerException.class, () -> {
@@ -182,6 +191,7 @@ public class DefBootstrapTests extends ESTestCase {
         DefBootstrap.MIC site = (DefBootstrap.MIC) DefBootstrap.bootstrap(MethodHandles.publicLookup(), 
                                                                "add", 
                                                                MethodType.methodType(Object.class, int.class, Object.class),
+                                                               0,
                                                                DefBootstrap.BINARY_OPERATOR, 0);
         MethodHandle handle = site.dynamicInvoker();
         assertEquals(2, (Object)handle.invokeExact(1, (Object)1));

modules/lang-painless/src/test/java/org/elasticsearch/painless/DefOptimizationTests.java

@@ -243,18 +243,22 @@ public class DefOptimizationTests extends ScriptTestCase {
     public void testAddOptNullGuards() {
         // needs null guard
         assertBytecodeHasPattern("def x = 1; def y = 2; return x + y", 
-                "(?s).*INVOKEDYNAMIC add.*arguments:\\s+" + DefBootstrap.BINARY_OPERATOR 
+                "(?s).*INVOKEDYNAMIC add.*arguments:\\s+" + "\\d+"
+                                                + ",\\s+" + DefBootstrap.BINARY_OPERATOR 
                                                 + ",\\s+" + DefBootstrap.OPERATOR_ALLOWS_NULL + ".*");
         // still needs null guard, NPE is the wrong thing!
         assertBytecodeHasPattern("def x = 1; def y = 2; double z = x + y", 
-                "(?s).*INVOKEDYNAMIC add.*arguments:\\s+" + DefBootstrap.BINARY_OPERATOR 
+                "(?s).*INVOKEDYNAMIC add.*arguments:\\s+" + "\\d+"
+                                                + ",\\s+" + DefBootstrap.BINARY_OPERATOR
                                                 + ",\\s+" + DefBootstrap.OPERATOR_ALLOWS_NULL + ".*");
         // a primitive argument is present: no null guard needed
         assertBytecodeHasPattern("def x = 1; int y = 2; return x + y", 
-                "(?s).*INVOKEDYNAMIC add.*arguments:\\s+" + DefBootstrap.BINARY_OPERATOR 
+                "(?s).*INVOKEDYNAMIC add.*arguments:\\s+" + "\\d+"
+                                                + ",\\s+" + DefBootstrap.BINARY_OPERATOR
                                                 + ",\\s+" + 0 + ".*");
         assertBytecodeHasPattern("int x = 1; def y = 2; return x + y", 
-                "(?s).*INVOKEDYNAMIC add.*arguments:\\s+" + DefBootstrap.BINARY_OPERATOR 
+                "(?s).*INVOKEDYNAMIC add.*arguments:\\s+" + "\\d+"
+                                                + ",\\s+" + DefBootstrap.BINARY_OPERATOR
                                                 + ",\\s+" + 0 + ".*");
     }
     

modules/lang-painless/src/test/java/org/elasticsearch/painless/ScriptTestCase.java

@@ -56,6 +56,7 @@ public abstract class ScriptTestCase extends ESTestCase {
     public Object exec(String script, Map<String, Object> vars) {
         Map<String,String> compilerSettings = new HashMap<>();
         compilerSettings.put(CompilerSettings.PICKY, "true");
+        compilerSettings.put(CompilerSettings.INITIAL_CALL_SITE_DEPTH, random().nextBoolean() ? "0" : "10");
         return exec(script, vars, compilerSettings, null);
     }