<s>
In	O
computing	O
,	O
an	O
extended	B-Application
basic	I-Application
block	I-Application
is	O
a	O
collection	O
of	O
basic	B-Application
blocks	I-Application
of	O
the	O
code	O
within	O
a	O
program	B-Application
with	O
certain	O
properties	O
that	O
make	O
them	O
highly	O
amenable	O
to	O
optimizations	O
.	O
</s>
<s>
Many	O
compiler	B-Application
optimizations	I-Application
operate	O
on	O
extended	B-Application
basic	I-Application
blocks	I-Application
.	O
</s>
<s>
An	O
extended	B-Application
basic	I-Application
block	I-Application
is	O
a	O
maximal	O
collection	O
of	O
basic	B-Application
blocks	I-Application
where	O
:	O
</s>
<s>
only	O
the	O
first	O
basic	B-Application
block	I-Application
can	O
have	O
multiple	O
predecessor	O
basic	B-Application
blocks	I-Application
;	O
</s>
<s>
all	O
the	O
other	O
basic	B-Application
blocks	I-Application
have	O
one	O
single	O
predecessor	O
basic	B-Application
block	I-Application
,	O
which	O
must	O
be	O
within	O
the	O
collection	O
of	O
basic	B-Application
blocks	I-Application
.	O
</s>
<s>
Many	O
local	O
optimizations	O
that	O
operate	O
on	O
basic	B-Application
blocks	I-Application
can	O
be	O
easily	O
extended	O
to	O
operate	O
on	O
extended	B-Application
basic	I-Application
blocks	I-Application
.	O
</s>
<s>
In	O
its	O
simplest	O
form	O
it	O
is	O
a	O
local	O
optimization	O
,	O
operating	O
only	O
on	O
basic	B-Application
blocks	I-Application
.	O
</s>
