<s>
In	O
computer	B-General_Concept
science	I-General_Concept
,	O
loop	B-Operating_System
dependence	I-Operating_System
analysis	I-Operating_System
is	O
a	O
process	O
which	O
can	O
be	O
used	O
to	O
find	O
dependencies	O
within	O
iterations	O
of	O
a	O
loop	O
with	O
the	O
goal	O
of	O
determining	O
different	O
relationships	O
between	O
statements	O
.	O
</s>
<s>
Using	O
the	O
analysis	O
of	O
these	O
relationships	O
,	O
execution	O
of	O
the	O
loop	O
can	O
be	O
organized	O
to	O
allow	O
multiple	O
processors	B-General_Concept
to	O
work	O
on	O
different	O
portions	O
of	O
the	O
loop	O
in	O
parallel	O
.	O
</s>
<s>
This	O
is	O
known	O
as	O
parallel	B-Operating_System
processing	I-Operating_System
.	O
</s>
<s>
Through	O
parallel	B-Operating_System
processing	I-Operating_System
,	O
it	O
is	O
possible	O
to	O
reduce	O
the	O
total	O
execution	O
time	O
of	O
a	O
program	O
through	O
sharing	O
the	O
processing	O
load	O
among	O
multiple	O
processors	B-General_Concept
.	O
</s>
<s>
The	O
process	O
of	O
organizing	O
statements	O
to	O
allow	O
multiple	O
processors	B-General_Concept
to	O
work	O
on	O
different	O
portions	O
of	O
a	O
loop	O
is	O
often	O
referred	O
to	O
as	O
parallelization	B-Operating_System
.	O
</s>
<s>
In	O
order	O
to	O
see	O
how	O
we	O
can	O
exploit	O
parallelization	B-Operating_System
,	O
we	O
have	O
to	O
first	O
analyze	O
the	O
dependencies	O
within	O
individual	O
loops	O
.	O
</s>
<s>
Loop	B-Operating_System
dependence	I-Operating_System
analysis	I-Operating_System
occur	O
on	O
a	O
normalized	B-Application
loop	I-Application
of	O
the	O
form	O
:	O
</s>
<s>
For	O
example	O
,	O
in	O
C	B-Language
:	O
</s>
<s>
When	O
a	O
possible	O
dependence	O
is	O
found	O
,	O
loop	B-Operating_System
dependence	I-Operating_System
analysis	I-Operating_System
usually	O
makes	O
every	O
attempt	O
to	O
characterize	O
the	O
relationship	O
between	O
dependent	O
instances	O
,	O
as	O
some	O
optimizations	O
may	O
still	O
be	O
possible	O
.	O
</s>
<s>
It	O
introduces	O
read-after-write	O
(	O
RAW	O
)	O
hazards	B-General_Concept
because	O
the	O
instruction	O
that	O
reads	O
from	O
the	O
location	O
in	O
memory	O
has	O
to	O
wait	O
until	O
it	O
is	O
written	O
to	O
by	O
the	O
previous	O
instruction	O
or	O
else	O
the	O
reading	O
instruction	O
will	O
read	O
the	O
wrong	O
value	O
.	O
</s>
<s>
This	O
introduces	O
write-after-read	O
(	O
WAR	O
)	O
hazards	B-General_Concept
because	O
the	O
instruction	O
that	O
writes	O
the	O
data	O
into	O
a	O
memory	O
location	O
has	O
to	O
wait	O
until	O
that	O
memory	O
location	O
has	O
been	O
read	O
by	O
the	O
previous	O
instruction	O
or	O
else	O
the	O
reading	O
instruction	O
would	O
read	O
the	O
wrong	O
value	O
.	O
</s>
<s>
This	O
introduces	O
write-after-write	O
(	O
WAW	O
)	O
hazards	B-General_Concept
because	O
the	O
second	O
instruction	O
to	O
write	O
the	O
value	O
to	O
a	O
memory	O
location	O
needs	O
to	O
wait	O
until	O
the	O
first	O
instruction	O
finishes	O
writing	O
data	O
to	O
the	O
same	O
memory	O
location	O
or	O
else	O
when	O
the	O
memory	O
location	O
is	O
read	O
at	O
a	O
later	O
time	O
it	O
will	O
contain	O
the	O
wrong	O
value	O
.	O
</s>
<s>
Here	O
,	O
the	O
variable	O
c	B-Language
is	O
first	O
written	O
to	O
in	O
S1	O
and	O
then	O
variable	O
c	B-Language
is	O
written	O
to	O
again	O
in	O
statement	O
S2	O
.	O
</s>
<s>
Here	O
,	O
c[j+1]	O
in	O
statement	O
S2	O
is	O
written	O
to	O
in	O
one	O
iteration	O
.	O
</s>
<s>
In	O
the	O
next	O
iteration	O
,	O
c[j]	O
in	O
statement	O
S2	O
,	O
which	O
is	O
the	O
same	O
memory	O
location	O
as	O
c[j+1]	O
in	O
the	O
previous	O
iteration	O
,	O
is	O
written	O
to	O
again	O
.	O
</s>
<s>
c	B-Language
=	O
"	O
controlled	O
"	O
;	O
</s>
<s>
c	B-Language
=	O
"	O
controlled	O
"	O
;	O
</s>
<s>
c	B-Language
=	O
"	O
controlled	O
"	O
;	O
</s>
<s>
Code	O
block	O
1	O
shows	O
the	O
correct	O
ordering	O
when	O
using	O
an	O
if	O
statement	O
in	O
the	O
C	B-Language
programming	I-Language
language	I-Language
.	O
</s>
