Consider the following code segment. x = u - t; y = x * v; x = y + w; y = t -…
2016
Consider the following code segment.
x = u - t;
y = x * v;
x = y + w;
y = t - z;
y = x * y;
The minimum number of total variables required to convert the above code segment to static single assignment form is __________ .
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Correct answer: 10
Key idea: in static single assignment (SSA) form every assignment to a variable creates a new version of that variable; variables that are never assigned keep a single version.
x1 = u - t
y1 = x1 * v
x2 = y1 + w
y2 = t - z
y3 = x2 * y2
Count the distinct names after versioning: x1, x2, y1, y2, y3, u, t, v, w, z — total 10 variables.
Answer: 10
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