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package com.oracle.truffle.llvm.runtime.nodes.control;

import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.frame.VirtualFrame;
import com.oracle.truffle.api.nodes.ExplodeLoop;
import com.oracle.truffle.llvm.runtime.nodes.vars.LLVMWriteNode;
import com.oracle.truffle.llvm.runtime.nodes.api.LLVMExpressionNode;
import com.oracle.truffle.llvm.runtime.nodes.api.LLVMStatementNode;

public abstract class LLVMWritePhisNode extends LLVMStatementNode {

    @Children private final LLVMExpressionNode[] cycleFrom;
    @Children private final LLVMWriteNode[] cycleWrites;
    @Children private final LLVMWriteNode[] ordinaryWrites;

    public LLVMWritePhisNode(LLVMExpressionNode[] cycleFrom, LLVMWriteNode[] cycleWrites, LLVMWriteNode[] ordinaryWrites) {
        this.ordinaryWrites = ordinaryWrites;
        this.cycleFrom = cycleFrom;
        this.cycleWrites = cycleWrites;
        assert cycleFrom.length == cycleWrites.length;
    }

    @Specialization
    void doWritePhis(VirtualFrame frame) {
        if (cycleFrom.length == 0) {
            writeOrdinaryValues(frame);
        } else {
            // some values need to be kept in temporary storage
            Object[] values = readCycleValues(frame);
            writeOrdinaryValues(frame);
            writeCycleValues(frame, values);
        }
    }

    @ExplodeLoop
    private Object[] readCycleValues(VirtualFrame frame) {
        Object[] result = new Object[cycleFrom.length];
        for (int i = 0; i < cycleFrom.length; i++) {
            result[i] = cycleFrom[i].executeGeneric(frame);
        }
        return result;
    }

    @ExplodeLoop
    private void writeCycleValues(VirtualFrame frame, Object[] values) {
        for (int i = 0; i < cycleWrites.length; i++) {
            cycleWrites[i].executeWithTarget(frame, values[i]);
        }
    }

    @ExplodeLoop
    private void writeOrdinaryValues(VirtualFrame frame) {
        for (int i = 0; i < ordinaryWrites.length; i++) {
            ordinaryWrites[i].execute(frame);
        }
    }
}