Live-variable analysis: Difference between revisions

Revision as of 15:40, 14 November 2019

Revision as of 14:47, 16 August 2020

Line 8:

a = f(b * c)

The set of live variables between lines 21 and 32 is {<code>b</code>, <code>c</code>} because both are used in the multiplication on line 3. But the set of live variables after line 1 is only {<code>b</code>}, since variable <code>c</code> is updated later, on line 2. The value of variable <code>a</code> is not used in this code.

Note that the assignment to <code>a</code> may be eliminated as <code>a</code> is not used later, but there is insufficient information to justify removing all of line 3 as <code>f</code> may have side effects (printing <code>b * c</code>, perhaps).