Code flow & analysis
Data flow analysis in Compiler
It is the analysis of flow of data in control flow graph, i.e., the
analysis that determines the information regarding the definition and
use of data in program. With the help of this analysis, optimization can
be done. In general, its process in which values are computed using
data flow analysis. The data flow property represents information that
can be used for optimization.
Basic Terminologies –
- Definition Point: a point in a program containing some definition.
- Reference Point: a point in a program containing a reference to a data item.
- Evaluation Point: a point in a program containing evaluation of expression.
Data Flow Properties –
- Available Expression –
A expression is said to be available at a program point x if along
paths its reaching to x. A Expression is available at its evaluation
point.
An expression a+b is said to be available if none of the operands gets modified before their use. Example –
Advantage –
document.addEventListener("DOMContentLoaded", function () {
/* -------- Date Helpers -------- */
function addDays(date, days) {
const d = new Date(date);
d.setDate(d.getDate() + days);
return d;
}
function isWorkingDay(date) {
const day = date.getDay(); // 0=Sun, 6=Sat
return day !== 0 && day !== 6; // Mon-Fri only
}
function addWorkingDays(startDate, days) {
let current = new Date(startDate);
let remaining = days;
while (remaining > 0) {
current = addDays(current, 1);
if (isWorkingDay(current)) {
remaining--;
}
}
return current;
}
function formatDate(date) {
return date.toISOString().split('T')[0]; // YYYY-MM-DD
}
/* -------- DOM Wiring -------- */
const calcButton = document.getElementById("calcBtn");
const daysInput = document.getElementById("daysInput");
const typeContainer = document.getElementById("typeContainer");
const dayTypeSelect = document.getElementById("dayType");
const resultDiv = document.getElementById("result");
if (!calcButton || !daysInput || !typeContainer || !dayTypeSelect || !resultDiv) {
console.error("Required DOM elements missing");
return;
}
let enteredDays = 0;
calcButton.addEventListener("click", function () {
enteredDays = parseInt(daysInput.value, 10);
if (!Number.isInteger(enteredDays) || enteredDays < 0) {
resultDiv.textContent = "Please enter a valid non-negative integer.";
resultDiv.style.color = "red";
return;
}
typeContainer.style.display = "block";
dayTypeSelect.value = "";
resultDiv.textContent = "";
});
dayTypeSelect.addEventListener("change", function () {
if (enteredDays === 0) return;
const today = new Date();
let resultDate;
if (dayTypeSelect.value === "working") {
resultDate = addWorkingDays(today, enteredDays);
} else {
resultDate = addDays(today, enteredDays);
}
const formatted = formatDate(resultDate);
resultDiv.textContent = `Result date: ${formatted}`;
resultDiv.style.color = "green";
// Reset
enteredDays = 0;
typeContainer.style.display = "none";
dayTypeSelect.value = "";
daysInput.value = "";
});
});