/**
* Branching code generation for == operation.
*
* @param output the code emitter (basically an abstraction for producing the .class file).
* @param targetLabel target for generated branch instruction.
* @param onTrue should we branch on true?
*/
public void codegen(CLEmitter output, String targetLabel, boolean onTrue) {
lhs.codegen(output);
rhs.codegen(output);
if (lhs.type().isReference()) {
output.addBranchInstruction(onTrue ? IF_ACMPEQ : IF_ACMPNE, targetLabel);
} else {
output.addBranchInstruction(onTrue ? IF_ICMPEQ : IF_ICMPNE, targetLabel);
}
}
/**
* The semantics of j-- require that we implement short-circuiting branching in implementing the
* logical AND.
*
* @param output the code emitter (basically an abstraction for producing the .class file).
* @param targetLabel target for generated branch instruction.
* @param onTrue should we branch on true?
*/
public void codegen(CLEmitter output, String targetLabel, boolean onTrue) {
if (onTrue) {
String falseLabel = output.createLabel();
lhs.codegen(output, falseLabel, false);
rhs.codegen(output, targetLabel, true);
output.addLabel(falseLabel);
} else {
lhs.codegen(output, targetLabel, false);
rhs.codegen(output, targetLabel, false);
}
}
/**
* Generate code for the case where we actually want a boolean value (true or false) computed onto
* the stack, eg for assignment to a boolean variable.
*
* @param output the code emitter (basically an abstraction for producing the .class file).
*/
public void codegen(CLEmitter output) {
String elseLabel = output.createLabel();
String endIfLabel = output.createLabel();
this.codegen(output, elseLabel, false);
output.addNoArgInstruction(ICONST_1); // true
output.addBranchInstruction(GOTO, endIfLabel);
output.addLabel(elseLabel);
output.addNoArgInstruction(ICONST_0); // false
output.addLabel(endIfLabel);
}