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Bytecode: Avoid casts to supertype (#205)
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@dstepanov
dstepanov authored Dec 5, 2024
1 parent a784414 commit 355e935
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Showing 11 changed files with 312 additions and 93 deletions.
88 changes: 64 additions & 24 deletions ...writer/src/main/java/io/micronaut/sourcegen/bytecode/expression/CastExpressionWriter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,9 +18,12 @@
import io.micronaut.inject.ast.ClassElement;
import io.micronaut.sourcegen.bytecode.MethodContext;
import io.micronaut.sourcegen.bytecode.TypeUtils;
import io.micronaut.sourcegen.model.ClassDef;
import io.micronaut.sourcegen.model.ClassTypeDef;
import io.micronaut.sourcegen.model.EnumDef;
import io.micronaut.sourcegen.model.ExpressionDef;
import io.micronaut.sourcegen.model.ObjectDef;
import io.micronaut.sourcegen.model.RecordDef;
import io.micronaut.sourcegen.model.TypeDef;
import org.objectweb.asm.commons.GeneratorAdapter;

Expand Down Expand Up @@ -61,34 +64,71 @@ private static void cast(GeneratorAdapter generatorAdapter, MethodContext contex
if (!from.isPrimitive() && to.isPrimitive()) {
unbox(generatorAdapter, context, to);
}
} else if (!from.makeNullable().equals(to.makeNullable())) {
if (from instanceof ClassTypeDef.ClassElementType fromElement) {
ClassElement fromClassElement = fromElement.classElement();
if (to instanceof ClassTypeDef.ClassElementType toElement) {
if (!fromClassElement.isAssignable(toElement.classElement())) {
checkCast(generatorAdapter, context, from, to);
}
} else if (to instanceof ClassTypeDef.JavaClass toClass) {
if (!fromClassElement.isAssignable(toClass.type())) {
checkCast(generatorAdapter, context, from, to);
}
} else if (to instanceof ClassTypeDef.ClassName toClassName) {
if (!fromClassElement.isAssignable(toClassName.className())) {
checkCast(generatorAdapter, context, from, to);
}
} else {
checkCast(generatorAdapter, context, from, to);
}
} else if (from instanceof ClassTypeDef.JavaClass fromClass && to instanceof ClassTypeDef.JavaClass toClass) {
if (!toClass.type().isAssignableFrom(fromClass.type())) {
checkCast(generatorAdapter, context, from, to);
}
} else {
checkCast(generatorAdapter, context, from, to);
} else if (needsCast(from, to)) {
checkCast(generatorAdapter, context, from, to);
}
}

private static boolean needsCast(TypeDef from, TypeDef to) {
if (from.makeNullable().equals(to.makeNullable())) {
return false;
}
if (from instanceof ClassTypeDef.Parameterized parameterized) {
return needsCast(parameterized.rawType(), to);
}
if (to instanceof ClassTypeDef.Parameterized parameterized) {
return needsCast(from, parameterized.rawType());
}
if (from instanceof ClassTypeDef.ClassElementType fromElement) {
return needsCast(fromElement.classElement(), to);
}
if (from instanceof ClassTypeDef.JavaClass fromClass) {
if (to instanceof ClassTypeDef.JavaClass toClass) {
return !toClass.type().isAssignableFrom(fromClass.type());
}
}
if (from instanceof ClassTypeDef.ClassDefType fromClassDef) {
ClassTypeDef fromSuperclass = getSuperclass(fromClassDef.objectDef());
if (fromSuperclass != null) {
return needsCast(fromSuperclass, to);
}
}
return true;
}

private static boolean needsCast(ClassElement from, TypeDef to) {
if (to instanceof ClassTypeDef.ClassElementType toElement) {
return !from.isAssignable(toElement.classElement());
}
if (to instanceof ClassTypeDef.JavaClass toClass) {
return !from.isAssignable(toClass.type());
}
if (to instanceof ClassTypeDef.ClassName toClassName) {
return !from.isAssignable(toClassName.name());
}
if (to instanceof ClassTypeDef.ClassDefType toClassDefType) {
if (from.isAssignable(toClassDefType.getName())) {
return false;
}
return !from.isAssignable(toClassDefType.getName());
}
return true;
}

private static ClassTypeDef getSuperclass(ObjectDef objectDef) {
if (objectDef instanceof ClassDef classDef) {
return classDef.getSuperclass();
}
if (objectDef instanceof EnumDef) {
return ClassTypeDef.of(Enum.class);
}
if (objectDef instanceof RecordDef) {
return ClassTypeDef.of(Record.class);
}
return null;
}


private static void checkCast(GeneratorAdapter generatorAdapter, MethodContext context, TypeDef from, TypeDef to) {
TypeDef toType = ObjectDef.getContextualType(context.objectDef(), to);
if (!toType.makeNullable().equals(from.makeNullable())) {
Expand Down
165 changes: 165 additions & 0 deletions ...gen-bytecode-writer/src/test/java/io/micronaut/sourcegen/bytecode/ByteCodeWriterTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,8 @@
import java.io.PrintStream;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.AbstractList;
import java.util.List;
import java.util.Map;

import static io.micronaut.sourcegen.bytecode.DecompilerUtils.decompileToJava;
Expand Down Expand Up @@ -1519,6 +1521,169 @@ Object invoke() {
""", decompileToJava(bytes));
}

@Test
void testCastingClassDefWithSuperclass() {

ClassDef myList = ClassDef.builder("example.MyList")
.superclass(ClassTypeDef.of(AbstractList.class))
.build();

ClassDef classDef = ClassDef.builder("example.Test")
.addMethod(MethodDef.builder("load")
.returns(ClassTypeDef.of(List.class))
.build((aThis, methodParameters) -> myList.asTypeDef()
.instantiate().returning())
)
.build();

StringWriter bytecodeWriter = new StringWriter();
byte[] bytes = generateFile(classDef, bytecodeWriter);

String bytecode = bytecodeWriter.toString();

Assertions.assertEquals("""
// class version 61.0 (61)
// access flags 0x0
// signature Ljava/lang/Object;
// declaration: example/Test
class example/Test {
// access flags 0x0
<init>()V
ALOAD 0
INVOKESPECIAL java/lang/Object.<init> ()V
RETURN
// access flags 0x0
load()Ljava/util/List;
NEW example/MyList
DUP
INVOKESPECIAL example/MyList.<init> ()V
ARETURN
}
""", bytecode);

Assertions.assertEquals("""
package example;
import java.util.List;
class Test {
List load() {
return new MyList();
}
}
""", decompileToJava(bytes));
}

@Test
void testCastingThisClassDefWithSuperclass() {

ClassDef classDef = ClassDef.builder("example.Test")
.superclass(TypeDef.parameterized(AbstractList.class, Number.class))
.addMethod(MethodDef.builder("load")
.returns(ClassTypeDef.of(List.class))
.build((aThis, methodParameters) -> aThis.type().instantiate().returning())
)
.build();

StringWriter bytecodeWriter = new StringWriter();
byte[] bytes = generateFile(classDef, bytecodeWriter);

String bytecode = bytecodeWriter.toString();

Assertions.assertEquals("""
// class version 61.0 (61)
// access flags 0x0
// signature Ljava/util/AbstractList<Ljava/lang/Number;>;
// declaration: example/Test extends java.util.AbstractList<java.lang.Number>
class example/Test extends java/util/AbstractList {
// access flags 0x0
<init>()V
ALOAD 0
INVOKESPECIAL java/util/AbstractList.<init> ()V
RETURN
// access flags 0x0
load()Ljava/util/List;
NEW example/Test
DUP
INVOKESPECIAL example/Test.<init> ()V
ARETURN
}
""", bytecode);

Assertions.assertEquals("""
package example;
import java.util.AbstractList;
import java.util.List;
class Test extends AbstractList {
List load() {
return new Test();
}
}
""", decompileToJava(bytes));
}

@Test
void testCastingEnum() {

EnumDef enumDef = EnumDef.builder("example.MyEnum")
.addEnumConstant("A")
.addEnumConstant("B")
.build();

ClassDef classDef = ClassDef.builder("example.Test")
.addMethod(MethodDef.builder("load")
.returns(Enum.class)
.build((aThis, methodParameters) -> enumDef.asTypeDef()
.getStaticField(enumDef.getField("A"))
.returning())
)
.build();

StringWriter bytecodeWriter = new StringWriter();
byte[] bytes = generateFile(classDef, bytecodeWriter);

String bytecode = bytecodeWriter.toString();

Assertions.assertEquals("""
// class version 61.0 (61)
// access flags 0x0
// signature Ljava/lang/Object;
// declaration: example/Test
class example/Test {
// access flags 0x0
<init>()V
ALOAD 0
INVOKESPECIAL java/lang/Object.<init> ()V
RETURN
// access flags 0x0
load()Ljava/lang/Enum;
GETSTATIC example/MyEnum.A : Lexample/MyEnum;
ARETURN
}
""", bytecode);

Assertions.assertEquals("""
package example;
class Test {
Enum load() {
return MyEnum.A;
}
}
""", decompileToJava(bytes));
}

private String toBytecode(ObjectDef objectDef) {
StringWriter stringWriter = new StringWriter();
generateFile(objectDef, stringWriter);
Expand Down
22 changes: 13 additions & 9 deletions sourcegen-model/src/main/java/io/micronaut/sourcegen/model/ClassDef.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,7 @@ public final class ClassDef extends ObjectDef {
private final ClassTypeDef superclass;
private final StatementDef staticInitializer;

private ClassDef(ClassTypeDef type,
private ClassDef(ClassTypeDef.ClassName className,
EnumSet<Modifier> modifiers,
List<FieldDef> fields,
List<MethodDef> methods,
Expand All @@ -52,16 +52,17 @@ private ClassDef(ClassTypeDef type,
ClassTypeDef superclass,
List<ObjectDef> innerTypes,
StatementDef staticInitializer) {
super(type, modifiers, annotations, javadoc, methods, properties, superinterfaces, innerTypes);
super(className, modifiers, annotations, javadoc, methods, properties, superinterfaces, innerTypes);
ClassTypeDef.of(this);
this.fields = fields;
this.typeVariables = typeVariables;
this.superclass = superclass;
this.staticInitializer = staticInitializer;
}

@Override
public ClassDef withType(ClassTypeDef type) {
return new ClassDef(type, modifiers, fields, methods, properties, annotations, javadoc, typeVariables, superinterfaces, superclass, innerTypes, staticInitializer);
public ClassDef withClassName(ClassTypeDef.ClassName className) {
return new ClassDef(className, modifiers, fields, methods, properties, annotations, javadoc, typeVariables, superinterfaces, superclass, innerTypes, staticInitializer);
}

@Override
Expand Down Expand Up @@ -108,7 +109,7 @@ public FieldDef findField(String name) {
public FieldDef getField(String name) {
FieldDef field = findField(name);
if (field == null) {
throw new IllegalStateException("Class: " + this.name + " doesn't have a field: " + name);
throw new IllegalStateException("Class: " + this.className + " doesn't have a field: " + name);
}
return null;
}
Expand All @@ -122,8 +123,11 @@ public boolean hasField(String name) {
if (superclass instanceof ClassTypeDef.ClassElementType classElementType) {
return classElementType.classElement().findField(name).isPresent();
}
if (superclass instanceof ClassTypeDef.ClassDefType classDefType) {
return classDefType.classDef().hasField(name);
if (superclass instanceof ClassTypeDef.ClassDefType classDefType && classDefType.objectDef() instanceof ClassDef classDef) {
return classDef.hasField(name);
}
if (superclass instanceof ClassTypeDef.ClassDefType classDefType && classDefType.objectDef() instanceof EnumDef enumDef) {
return enumDef.hasField(name);
}
if (superclass instanceof ClassTypeDef.JavaClass javaClass) {
try {
Expand All @@ -146,7 +150,7 @@ public StatementDef getStaticInitializer() {

@Override
public String toString() {
return "ClassDef{" + "name='" + name + '\'' + '}';
return "ClassDef{" + "name='" + className + '\'' + '}';
}

/**
Expand Down Expand Up @@ -199,7 +203,7 @@ public ClassDefBuilder addStaticInitializer(StatementDef staticInitializer) {
}

public ClassDef build() {
return new ClassDef(ClassTypeDef.of(name), modifiers, fields, methods, properties, annotations, javadoc, typeVariables, superinterfaces, superclass, innerTypes, staticInitializer);
return new ClassDef(new ClassTypeDef.ClassName(name), modifiers, fields, methods, properties, annotations, javadoc, typeVariables, superinterfaces, superclass, innerTypes, staticInitializer);
}

/**
Expand Down
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