<s>
In	O
compiler	O
theory	O
,	O
a	O
greatest	O
common	O
divisor	O
test	O
(	O
GCD	B-Application
test	I-Application
)	O
is	O
the	O
test	O
used	O
in	O
study	O
of	O
loop	O
optimization	O
and	O
loop	B-Operating_System
dependence	I-Operating_System
analysis	I-Operating_System
to	O
test	O
the	O
dependency	O
between	O
loop	O
statements	O
.	O
</s>
<s>
A	O
greatest	O
common	O
divisor	O
(	O
GCD	O
)	O
test	O
is	O
a	O
test	O
used	O
in	O
computer	O
science	O
compiler	O
theory	O
to	O
study	O
of	O
loop	O
optimization	O
and	O
loop	B-Operating_System
dependence	I-Operating_System
analysis	I-Operating_System
to	O
test	O
the	O
dependency	O
between	O
loop	O
statements	O
.	O
</s>
<s>
Whenever	O
a	O
sequential	O
loop	O
like	O
for	B-Language
loop	I-Language
is	O
made	O
to	O
be	O
parallel	O
so	O
that	O
it	O
can	O
be	O
executed	O
on	O
more	O
than	O
one	O
processor	B-General_Concept
—	O
as	O
in	O
case	O
of	O
grid	B-Architecture
computing	I-Architecture
or	O
cluster	B-Architecture
computing	I-Architecture
—	O
then	O
certain	O
dependencies	O
(	O
e.g.	O
,	O
testing	O
the	O
flow	O
(	O
true	O
)	O
dependence	O
of	O
a	O
statement	O
)	O
are	O
checked	O
to	O
know	O
whether	O
the	O
loop	O
can	O
be	O
parallelized	B-Operating_System
.	O
</s>
<s>
According	O
to	O
this	O
test	O
,	O
by	O
comparing	O
the	O
indices	O
of	O
two	O
arrays	B-Data_Structure
present	O
in	O
two	O
or	O
more	O
statements	O
,	O
it	O
can	O
be	O
calculated	O
whether	O
it	O
is	O
legal	O
to	O
parallelize	O
the	O
loop	O
or	O
not	O
.	O
</s>
<s>
The	O
assumption	O
is	O
that	O
the	O
loop	O
must	O
be	O
normalized	B-Application
–	O
written	O
so	O
that	O
the	O
loop	O
index/variable	O
starts	O
at	O
1	O
and	O
gets	O
incremented	O
by	O
1	O
in	O
every	O
iteration	O
.	O
</s>
