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First step of code cleanup and refactoring.

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Moved the localVarIndex setters into a separate helperClass and optimized bytecodesize in regard to variable pushes
This commit is contained in:
Jochen Seyfried 2024-07-04 18:37:54 +02:00
parent aed7af7c68
commit 3e908293ee
11 changed files with 75 additions and 103 deletions
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36
src/main/java/CodeGen/CodeGenHelper.java Normal file
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@ -0,0 +1,36 @@
package CodeGen;
import abstractSyntaxTree.Expression.SubReceiver;
import java.util.LinkedHashMap;
import java.util.List;
public class CodeGenHelper {
public static String getFieldDescriptor(String type) {
switch (type) {
case "int":
return "I";
case "boolean":
return "Z";
case "char":
return "C";
default:
return "L" + type + ";";
}
}
public static int GetLocalVarIndex(LinkedHashMap<String, String> localVars, String varToSearchFor) {
int index = -1;
int counter = 0;
for (String key : localVars.keySet()) {
if (key.equals(varToSearchFor)) {
index = counter + 1; // +1 because the first local variable is at index 1, 0 is used for "this"
break;
}
counter++;
}
return index;
}
}

17
src/main/java/abstractSyntaxTree/Class/FieldDecl.java
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@ -1,5 +1,6 @@
package abstractSyntaxTree.Class;
import CodeGen.CodeGenHelper;
import TypeCheck.AbstractType;
import TypeCheck.TypeCheckException;
import TypeCheck.TypeCheckHelper;
@ -47,23 +48,11 @@ public class FieldDecl extends AbstractType implements Node {
}
public void codeGen(ClassWriter cw) {
FieldVisitor fv = cw.visitField(Opcodes.ACC_PUBLIC, identifier, getFieldDescriptor(), null, null);
String descriptor = CodeGenHelper.getFieldDescriptor(type);
FieldVisitor fv = cw.visitField(Opcodes.ACC_PUBLIC, identifier, descriptor, null, null);
fv.visitEnd();
}
private String getFieldDescriptor() {
switch (type) {
case "int":
return "I";
case "boolean":
return "Z";
case "char":
return "C";
default:
return "L" + type + ";";
}
}
@Override
public boolean equals(Object o) {
if (this == o) return true;

16
src/main/java/abstractSyntaxTree/Class/MethodDecl.java
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@ -1,5 +1,6 @@
package abstractSyntaxTree.Class;
import CodeGen.CodeGenHelper;
import TypeCheck.TypeCheckException;
import TypeCheck.TypeCheckResult;
import abstractSyntaxTree.Node;
@ -91,7 +92,7 @@ public class MethodDecl implements Node {
default -> mv.visitInsn(Opcodes.ACONST_NULL);
}
}
descriptor = getFieldDescriptor(field.type);
descriptor = CodeGenHelper.getFieldDescriptor(field.type);
mv.visitFieldInsn(Opcodes.PUTFIELD, classThatContainsMethod, fieldName, descriptor);
fieldFound = true;
break;
@ -215,19 +216,6 @@ public class MethodDecl implements Node {
return descriptor.toString();
}
private String getFieldDescriptor(String type) {
switch (type) {
case "int":
return "I";
case "boolean":
return "Z";
case "char":
return "C";
default:
return "L" + type + ";";
}
}
@Override
public boolean equals(Object o) {
if (this == o) return true;

13
src/main/java/abstractSyntaxTree/Datatype/CharDatatype.java
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@ -3,6 +3,7 @@ package abstractSyntaxTree.Datatype;
import TypeCheck.AbstractType;
import TypeCheck.TypeCheckResult;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import java.util.Objects;
@ -21,11 +22,13 @@ public class CharDatatype extends AbstractType implements IDatatype{
@Override
public void codeGen(MethodVisitor mv) throws Exception {
// Possible use of BIPUSH and SIPUSH if the value is small enough
//This saves space in the bytecode which is not very relevant at this point, but could be implemented anyway
mv.visitLdcInsn((int)value);
if (value <= 5) {
mv.visitInsn(Opcodes.ICONST_0 + value);
} else if (value <= Byte.MAX_VALUE) {
mv.visitIntInsn(Opcodes.BIPUSH, value);
} else {
mv.visitIntInsn(Opcodes.SIPUSH, value);
}
}
@Override
public boolean equals(Object o) {

2
src/main/java/abstractSyntaxTree/Datatype/IntDatatype.java
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@ -21,8 +21,6 @@ public class IntDatatype extends AbstractType implements IDatatype{
@Override
public void codeGen(MethodVisitor mv) throws Exception {
//Example of using BIPUSH and SIPUSH for optimizing bytecode size
if (value >= Byte.MIN_VALUE && value <= Byte.MAX_VALUE)
mv.visitIntInsn(Opcodes.BIPUSH, value);
else if (value >= Short.MIN_VALUE && value <= Short.MAX_VALUE)

8
src/main/java/abstractSyntaxTree/Expression/CharConstantExpression.java
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@ -27,7 +27,13 @@ public class CharConstantExpression extends AbstractType implements IExpression{
@Override
public void codeGen(MethodVisitor mv, LinkedHashMap<String, String> localVars, HashMap<String, HashMap<String, String>> typeContext, HashMap<String, HashMap<String, HashMap<String, ParameterList>>> methodContext) throws Exception {
mv.visitIntInsn(Opcodes.BIPUSH, (int) value);
if (value <= 5) {
mv.visitInsn(Opcodes.ICONST_0 + value);
} else if (value <= Byte.MAX_VALUE) {
mv.visitIntInsn(Opcodes.BIPUSH, value);
} else {
mv.visitIntInsn(Opcodes.SIPUSH, value);
}
}
@Override

41
src/main/java/abstractSyntaxTree/Expression/InstVarExpression.java
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@ -1,5 +1,6 @@
package abstractSyntaxTree.Expression;
import CodeGen.CodeGenHelper;
import TypeCheck.AbstractType;
import TypeCheck.TypeCheckException;
import TypeCheck.TypeCheckResult;
@ -74,15 +75,7 @@ public class InstVarExpression extends AbstractType implements IExpression {
if (i == 0) {
// Load the local variable onto the stack
int index = -1;
int counter = 0;
for (String key : localVars.keySet()) {
if (key.equals(this.receivers.get(i).identifier)) {
index = counter + 1; // +1 because the first local variable is at index 1, 0 is used for "this"
break;
}
counter++;
}
int index = CodeGenHelper.GetLocalVarIndex(localVars, this.receivers.get(i).identifier);
if (index == -1) {
if (typeContext.get(thisClass).get(this.receivers.get(i).identifier) != null) {
@ -119,15 +112,7 @@ public class InstVarExpression extends AbstractType implements IExpression {
else {
// Load the local variable onto the stack
int index = -1;
int counter = 0;
for (String key : localVars.keySet()) {
if (key.equals(this.receivers.get(i).identifier)) {
index = counter + 1; // +1 because the first local variable is at index 1, 0 is used for "this"
break;
}
counter++;
}
int index = CodeGenHelper.GetLocalVarIndex(localVars, this.receivers.get(i).identifier);
if (index == -1) {
if (typeContext.get(typeOfReciever).get(this.receivers.get(i).identifier) != null) {
@ -157,15 +142,7 @@ public class InstVarExpression extends AbstractType implements IExpression {
// Load the field in fieldName
// Load the local variable onto the stack
int index = -1;
int counter = 0;
for (String key : localVars.keySet()) {
if (key.equals(fieldName)) {
index = counter + 1; // +1 because the first local variable is at index 1, 0 is used for "this"
break;
}
counter++;
}
int index = CodeGenHelper.GetLocalVarIndex(localVars, fieldName);
if (index == -1) {
if (typeContext.get(typeOfReciever).get(fieldName) != null) {
@ -192,15 +169,7 @@ public class InstVarExpression extends AbstractType implements IExpression {
}
} else if (receivers.get(0).thisExpression) {
// Load the local variable or instVar of this onto the stack
int index = -1;
int counter = 0;
for (String key : localVars.keySet()) {
if (key.equals(fieldName)) {
index = counter + 1; // +1 because the first local variable is at index 1, 0 is used for "this"
break;
}
counter++;
}
int index = CodeGenHelper.GetLocalVarIndex(localVars, fieldName);
if (index == -1) {
mv.visitVarInsn(Opcodes.ALOAD, 0);

11
src/main/java/abstractSyntaxTree/Expression/IntConstantExpression.java
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@ -28,8 +28,15 @@ public class IntConstantExpression extends AbstractType implements IExpression{
@Override
public void codeGen(MethodVisitor mv, LinkedHashMap<String, String> localVars, HashMap<String, HashMap<String, String>> typeContext, HashMap<String, HashMap<String, HashMap<String, ParameterList>>> methodContext) throws Exception {
//TODO: When we are finished this can be done more efficiently
mv.visitLdcInsn(value);
if (value >= -1 && value <= 5) {
mv.visitInsn(Opcodes.ICONST_0 + value);
} else if (value >= Byte.MIN_VALUE && value <= Byte.MAX_VALUE) {
mv.visitIntInsn(Opcodes.BIPUSH, value);
} else if (value >= Short.MIN_VALUE && value <= Short.MAX_VALUE) {
mv.visitIntInsn(Opcodes.SIPUSH, value);
} else {
mv.visitLdcInsn(value);
}
}
@Override

29
src/main/java/abstractSyntaxTree/Expression/LocalVarIdentifier.java
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@ -1,5 +1,6 @@
package abstractSyntaxTree.Expression;
import CodeGen.CodeGenHelper;
import TypeCheck.AbstractType;
import TypeCheck.TypeCheckException;
import TypeCheck.TypeCheckHelper;
@ -52,15 +53,7 @@ public class LocalVarIdentifier extends AbstractType implements IExpression{
if (localVars.containsKey(identifier)) {
type = localVars.get(identifier);
// Find the index of the variable
int index = -1;
int counter = 0;
for (String key : localVars.keySet()) {
if (key.equals(identifier)) {
index = counter + 1; // +1 because the first local variable is at index 1, 0 is used for "this"
break;
}
counter++;
}
int index = CodeGenHelper.GetLocalVarIndex(localVars, identifier);
if (index == -1) {
throw new Exception("Variable " + identifier + " not found");
@ -84,25 +77,13 @@ public class LocalVarIdentifier extends AbstractType implements IExpression{
// Load "this" onto the stack
mv.visitVarInsn(Opcodes.ALOAD, 0);
// Get the field from "this"
mv.visitFieldInsn(Opcodes.GETFIELD, thisClass, identifier, getFieldDescriptor(type));
String descriptor = CodeGenHelper.getFieldDescriptor(type);
mv.visitFieldInsn(Opcodes.GETFIELD, thisClass, identifier, descriptor);
} else
throw new Exception("Variable " + identifier + " not found");
}
//TODO move this to a helper class and remove the doubled code in MethodDecl and in other places
private String getFieldDescriptor(String type) {
switch (type) {
case "int":
return "I";
case "boolean":
return "Z";
case "char":
return "C";
default:
return "L" + type + ";";
}
}
@Override
public TypeCheckResult getTypeCheckResult() {
return super.getTypeCheckResult();

2
src/main/java/abstractSyntaxTree/Expression/UnaryExpression.java
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@ -2,9 +2,7 @@ package abstractSyntaxTree.Expression;
import TypeCheck.AbstractType;
import TypeCheck.TypeCheckException;
import TypeCheck.TypeCheckHelper;
import TypeCheck.TypeCheckResult;
import abstractSyntaxTree.Datatype.IDatatype;
import abstractSyntaxTree.Parameter.ParameterList;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;

3
src/main/java/abstractSyntaxTree/Statement/IfElseStatement.java
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@ -54,9 +54,6 @@ public class IfElseStatement extends AbstractType implements IStatement{
}
//TODO: There are 2 NOPs and one athrow on the stack between the if-Block and else-Block execution --> I have no idea why
// I think they are generated because of the jump operations below and can not be eliminated
// as they do not negatively impact the execution of the code logic wise we can ignore them
@Override
public void codeGen(MethodVisitor mv, LinkedHashMap<String, String> localVars, HashMap<String, HashMap<String, String>> typeContext, HashMap<String, HashMap<String, HashMap<String, ParameterList>>> methodContext) throws Exception {