CSG: Analysis within a Basic Block
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• A variable is live if it is used later in the block
live
next use
Example:
Textové pole: …
…
No occurrence of  variable “a”
Question: How to detect live variables effectively?
Answer: Apply backward finding¾that is, read the instructions from the block end towards its begin
Textové pole: …
…
(i) a := b + c
 
(j) d := a + b