Red Hat ENTERPRISE LINUX 4 Manual page 71

Chapter 4. GCC Command Options
}
Every language that wishes to perform language-specific alias analysis should define a function
that computes, given an
allowed to alias. For an example, see the C front-end function
Enabled at levels
-falign-functions
-falign-functions=
Align the start of functions to the next power-of-two greater than
For instance,
-falign-functions=32
-falign-functions=24
skipping 23 bytes or less.
-fno-align-functions
will not be aligned.
Some assemblers only support this flag when
If is not specified or is zero, use a machine-dependent default.
n
Enabled at levels
-falign-labels
-falign-labels=
n
Align all branch targets to a power-of-two boundary, skipping up to
-falign-functions
operations for when the branch target is reached in the usual flow of the code.
-fno-align-labels
aligned.
If
-falign-loops
values are used instead.
If is not specified or is zero, use a machine-dependent default which is very likely to be
n
meaning no alignment.
Enabled at levels
-falign-loops
-falign-loops=
n
Align loops to a power-of-two boundary, skipping up to
hope is that the loop will be executed many times, which will make up for any execution of the
dummy operations.
-fno-align-loops
aligned.
If is not specified or is zero, use a machine-dependent default.
n
Enabled at levels
-falign-jumps
-falign-jumps=
n
Align branch targets to a power-of-two boundary, for branch targets where the targets can only be
reached by jumping, skipping up to
operations need be executed.
-fno-align-jumps
aligned.
node, an alias set for the node. Nodes in different alias sets are not
tree
, , .
-O2 -O3 -Os
n
would align to the next 32-byte boundary only if this can be done by
and
-falign-functions=1
, .
-O2 -O3
. This option can easily make code slower, because it must insert dummy
and
-falign-labels=1
or
-falign-jumps
, .
-O2 -O3
and
-falign-loops=1
, .
-O2 -O3
bytes like
n
and
-falign-jumps=1
aligns functions to the next 32-byte boundary, but
are equivalent and mean that functions
is a power of two; in that case, it is rounded up.
n
are equivalent and mean that labels will not be
are applicable and are greater than this value, then their
bytes like
n
are equivalent and mean that loops will not be
-falign-functions
are equivalent and mean that loops will not be
.
c_get_alias_set
, skipping up to
n
n
-falign-functions
. In this case, no dummy
63
bytes.
n
bytes like
,
1
. The