Class JavaMethodWasmCodeBuilder

java.lang.Object

de.inetsoftware.jwebassembly.module.WasmCodeBuilder

de.inetsoftware.jwebassembly.module.JavaMethodWasmCodeBuilder

class JavaMethodWasmCodeBuilder
extends WasmCodeBuilder

Convert Java Byte Code to a list of WasmInstruction.

Field Summary

Fields

Modifier and Type	Field	Description
private BranchManager	branchManager

Fields inherited from class WasmCodeBuilder

CLASS_INIT, CONSTRUCTOR

Constructor Summary

Constructors

Constructor	Description
JavaMethodWasmCodeBuilder(WasmCodeBuilder codeBuilder)	Create an instance

Method Summary

Modifier and Type	Method	Description
(package private) void	buildCode(Code code, MethodInfo method)	Build the wasm instructions
private static int	findNext(int current, int[] values)	Find the next higher value.
(package private) void	init(WasmOptions options, ClassFileLoader classFileLoader)	Initialize the code builder;
private void	opCompare(ValueType valueType, CodeInputStream byteCode, int codePos, int lineNumber)	Handle the different compare operator.
private void	opIfCompareCondition(NumericOperator compareOp, CodeInputStream byteCode, int codePos, int lineNumber)	Handle the if of the Java byte code.
private void	opIfCondition(NumericOperator compareOp, CodeInputStream byteCode, int codePos, int lineNumber)	Handle the if of the Java byte code.
private void	patchTypeOfNullConst()	NULL const has no type in Java.
private void	writeCode(CodeInputStream byteCode, ConstantPool constantPool, ClassFile classFile, AnyType returnType)	Write the byte code of a method.
private void	writeSwitchCode(CodeInputStream byteCode, boolean isLookupSwitch)	Write the both switch operation codes

Methods inherited from class WasmCodeBuilder

addArrayInstruction, addBlockInstruction, addCallInstruction, addCallInterfaceInstruction, addCallVirtualInstruction, addConstInstruction, addConstInstruction, addConvertInstruction, addDupInstruction, addDupX1Instruction, addDupX2Instruction, addGlobalInstruction, addGlobalInstruction, addInvokeDynamic, addJumpPlaceholder, addLoadStoreInstruction, addLocalInstruction, addMemoryInstruction, addMultiNewArrayInstruction, addMultiNewArrayInstruction, addNopInstruction, addNumericInstruction, addStructInstruction, addTableInstruction, calculateVariables, findArrayTypeFromStack, findBlockStartCodePosition, findValueTypeFromStack, getInstructions, getLocalName, getLocalTypes, getLocalVariables, getOptions, getTempVariable, getTypeManager, isEndsWithReturn, reset

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

branchManager

private BranchManager branchManager

Constructor Details

JavaMethodWasmCodeBuilder

JavaMethodWasmCodeBuilder(@Nonnull
 WasmCodeBuilder codeBuilder)

Create an instance

Parameters:

codeBuilder - other code builder for shred references

Method Details

init

void init(WasmOptions options,
 ClassFileLoader classFileLoader)

Initialize the code builder;

Overrides:

init in class WasmCodeBuilder

Parameters:

options - compiler properties

classFileLoader - for loading the class files

buildCode

void buildCode(@Nonnull
 Code code,
 MethodInfo method)

Build the wasm instructions

Parameters:

code - the Java method code

method - the method with signature as fallback for a missing variable table

Throws:

WasmException - if some Java code can't converted

writeCode

private void writeCode(CodeInputStream byteCode,
 ConstantPool constantPool,
 ClassFile classFile,
 AnyType returnType)
                throws WasmException

Write the byte code of a method.

Parameters:

byteCode - a stream of byte code

constantPool - the constant pool of the the current class

classFile - the declaring class file

returnType - the return type of the method

Throws:

WasmException - if some Java code can't converted

writeSwitchCode

private void writeSwitchCode(CodeInputStream byteCode,
 boolean isLookupSwitch)
                      throws IOException

Write the both switch operation codes

Parameters:

byteCode - the current stream with a position after the operation code

isLookupSwitch - true, if the operation was a loopupswitch; false, if the operation was a tableswitch

Throws:

IOException - if any I/O error occur

findNext

private static int findNext(int current,
 int[] values)

Find the next higher value.

Parameters:

current - the current value

values - the unordered list of values

Returns:

the next value or current value if not found.

opIfCondition

private void opIfCondition(NumericOperator compareOp,
 CodeInputStream byteCode,
 int codePos,
 int lineNumber)
                    throws IOException

Handle the if of the Java byte code. This Java instruction compare the first stack value with value 0. Important: In the Java IF expression the condition for the jump to the else block is saved. In WebAssembler we need to use condition for the if block. The caller of the method must already negate this

Parameters:

compareOp - The condition for the continue of a loop.

byteCode - current byte code stream to read the target offset.

codePos - the code position/offset in the Java method

lineNumber - the line number in the Java source code

Throws:

IOException - if any I/O errors occur.

opIfCompareCondition

private void opIfCompareCondition(NumericOperator compareOp,
 CodeInputStream byteCode,
 int codePos,
 int lineNumber)
                           throws IOException

Handle the if of the Java byte code. This Java instruction compare 2 values from stack. Important: In the Java IF expression the condition for the jump to the else block is saved. In WebAssembler we need to use condition for the if block. The caller of the method must already negate this.

Parameters:

compareOp - The condition for the continue of a loop.

byteCode - current byte code stream to read the target offset.

codePos - the code position/offset in the Java method

lineNumber - the line number in the Java source code

Throws:

IOException - if any I/O errors occur.

opCompare

private void opCompare(ValueType valueType,
 CodeInputStream byteCode,
 int codePos,
 int lineNumber)
                throws IOException

Handle the different compare operator. The compare operator returns the integer values -1, 0 or 1. There is no equivalent in WebAssembly. That we need to read the next operation to find an equivalent.

Parameters:

valueType - the value type of the compared

byteCode - current byte code stream to read the next operation.

codePos - the code position/offset in the Java method

lineNumber - the line number in the Java source code

Throws:

IOException - if any I/O errors occur.

patchTypeOfNullConst

private void patchTypeOfNullConst()

NULL const has no type in Java. In WebAssembly currently.