Use-define Chain
A Use-Definition Chain (UD Chain) is a data structure that consists of a use, U, of a variable, and all the definitions, D, of that variable that can reach that use without any other intervening definitions. A definition can have many forms, but is generally taken to mean the assignment of some value to a variable (which is different from the use of the term that refers to the language construct involving a data type and allocating storage).
A counterpart of a UD Chain is a Definition-Use Chain (DU Chain), which consists of a definition, D, of a variable and all the uses, U, reachable from that definition without any other intervening definitions.
Both UD and DU chains are created by using a form of static code analysis known as data flow analysis. Knowing the use-def and def-use chains for a program or subprogram is a prerequisite for many compiler optimizations, including constant propagation and common subexpression elimination.
Read more about Use-define Chain: Purpose, Setup, Execution, Execution Example For Def-use-chain, Method of Building A use-def (or ud) Chain
Famous quotes containing the word chain:
“By this unprincipled facility of changing the state as often, and as much, and in as many ways as there are floating fancies or fashions, the whole chain and continuity of the commonwealth would be broken. No one generation could link with the other. Men would become little better than the flies of a summer.”
—Edmund Burke (1729–1797)