package org.jruby.compiler.ir.instructions;
import java.util.Map;
import org.jruby.compiler.ir.Operation;
import org.jruby.compiler.ir.operands.Variable;
import org.jruby.compiler.ir.operands.MetaObject;
import org.jruby.compiler.ir.IRExecutionScope;
import org.jruby.compiler.ir.IRMethod;
import org.jruby.compiler.ir.IRScope;
import org.jruby.compiler.ir.Interp;
import org.jruby.compiler.ir.operands.Label;
import org.jruby.compiler.ir.operands.LocalVariable;
import org.jruby.compiler.ir.operands.Operand;
import org.jruby.compiler.ir.representations.InlinerInfo;
import org.jruby.interpreter.InterpreterContext;
import org.jruby.runtime.builtin.IRubyObject;
/*
* All variables are allocated in the binding of the nearest method ancestor. Additionally, all variables
* with the same name in all closures (however deeply nested) get a single shared slot in the method's binding.
*
* So, when we encounter a load from binding instruction in some execution scope, we traverse the scope
* tree till we find a method. We are guaranteed to find one since closures dont float free --
* they are always tethered to a surrounding scope! This also means that we can find the neareast
* method ancestor by simply traversing lexical scopes -- no need to traverse the dynamic scopes
*
* SSS FIXME: except perhaps when we use class_eval, module_eval, or instance_eval??
*/
public class LoadFromBindingInstr extends Instr {
private IRMethod sourceMethod;
private int bindingSlot;
private String slotName;
public LoadFromBindingInstr(Variable v, IRExecutionScope scope, String slotName) {
super(Operation.BINDING_LOAD, v);
this.slotName = slotName;
this.sourceMethod = (IRMethod)scope.getClosestMethodAncestor();
bindingSlot = sourceMethod.assignBindingSlot(slotName);
}
public String getSlotName() {
return slotName;
}
public Operand[] getOperands() {
return new Operand[] { };
}
public void simplifyOperands(Map<Operand, Operand> valueMap) {
/* Nothing to do */
}
@Override
public String toString() {
return "\t" + result + " = BINDING(" + sourceMethod + ")." + getSlotName();
}
public Instr cloneForInlining(InlinerInfo ii) {
return new LoadFromBindingInstr(ii.getRenamedVariable(result), sourceMethod, getSlotName());
}
// Any exception raised by the execution of this instruction is an interpreter/compiler bug
@Override
public boolean canRaiseException() { return false; }
@Interp
@Override
public Label interpret(InterpreterContext interp, IRubyObject self) {
LocalVariable v = (LocalVariable)getResult();
if (bindingSlot == -1)
bindingSlot = sourceMethod.getBindingSlot(getSlotName());
interp.setLocalVariable(v.getLocation(), interp.getSharedBindingVariable(bindingSlot));
return null;
}
}