/**
* Generate code to fetch all the arguments needed for a given operand number and encoding. The
* different argument encodings of the Assembler need different arguments to be passed to the
* emitter function. For instance, a register-displacement mode operand needs to be given a base
* register and an immediate displacement. This function generates the appropriate arguments given
* the operand number and encoding; that is, it generates reads of the appropriate Instruction
* argument and fetches of the appropriate pieces of information from the operand.
*
* @param argNumber The argument being generated.
* @param argEcoding The encoding to use.
*/
private static void emitArgs(int argNumber, ArgumentType argEncoding) {
String op = getOperand(argNumber);
switch (argEncoding) {
case LabelOrImmediate:
emit("getImm(" + op + "), getLabel(" + op + ")");
break;
case RegisterDisplacement:
emit("getBase(" + op + "), getDisp(" + op + ")");
break;
case Absolute:
emit("getDisp(" + op + ").toWord().toAddress()");
break;
case RegisterOffset:
emit("getIndex(" + op + "), getScale(" + op + "), getDisp(" + op + ")");
break;
case RegisterIndexed:
emit(
"getBase(" + op + "), getIndex(" + op + "), getScale(" + op + "), getDisp(" + op + ")");
break;
case RegisterIndirect:
emit("getBase(" + op + ")");
break;
default:
emit("get" + argEncoding.getOptName() + "(" + op + ")");
}
}
/**
* For a given string representing a valid operand encoding for the Assembler, return the
* corresponding Assembler constant. This function only looks for encodings of operand types, and
* will not accept strings that correspond to size encodings.
*
* @param str A valid Assembler encoding of operand type
* @return The Assembler constant corresponding to str, or -1 if none
*/
private static ArgumentType getEncoding(String str, Class<?> type) {
if (str.equals("Reg")) {
if (type == null) {
throw new Error("Unable to encode Reg with no type information");
}
String typeName = type.getName();
str = typeName.substring(typeName.lastIndexOf('$') + 1) + "_Reg";
}
for (ArgumentType arg : ArgumentType.values()) {
if (arg.getOptName().equals(str)) {
return arg;
}
}
throw new Error(
"Unable to encode the argument " + str + " of type " + type + " as a valid argument type");
}
/**
* Given an operand number and an encoding, generate a test to determine whether the given operand
* matches the encoding. That is, generate code to the Assembler that examines a given operand of
* the current Instruction, and determines whether it is of the type encoded by the given
* encoding. This is used to generate the if statements of the dispatch functions for each opt
* compiler opcode.
*
* @param argNumber The argument to examine
* @param argEncoding The encoding for which to check
*/
private static void emitTest(int argNumber, ArgumentType argEncoding) {
if (argEncoding.isSize()) emit("is" + argEncoding.getOptName() + "(inst)");
else emit("is" + argEncoding.getOptName() + "(" + getOperand(argNumber) + ")");
}
