Execution example for def-use-chain Use-define chain

to find out def-use-chains variable d, following steps:

1.search first time, variable defined (write access).

in case d=b (l.3)

2.search first time, variable read.

in case return d

3.write down information in following style: [name of variable creating def-use-chain for, concrete write access, concrete read access]

in case is: [d, d=b, return d]

repeat steps in following style: combine each write access each read access (but not other way round).

the result should be:

you have take care, if variable changed time.

for example: line 3 down line 9 in source code, d not redefined / changed.

at line 10, d redefined, is, why have recombine write access on d possible read access, reached.

in case, code beyond line 6 relevant. line 3 example cannot reached again.

for understanding, can imagine 2 different variables d :

as result this. variable d1 replaced b