Tells the compiler how to align certain data items.
Windows:
Data > Structure Member Alignment (/align:recnbyte)
Data > Common Element Alignment (/align:[no]commons
or /align:[no]dcommons)
Data > SEQUENCE Types Obey Alignment Rules (/align:[no]sequence)
Linux: None
IA-32, IntelŪ EM64T, IntelŪ ItaniumŪ architecture
| Linux: | -align [keyword] -noalign |
| Windows: | /align[:keyword] /noalign |
| keyword | Specifies the data items to align. Possible values are: | |
| none | Prevents padding bytes anywhere in common blocks and structures. | |
| Affects alignment of common block entities. | ||
|
|
|
Affects alignment of common block entities. |
|
|
[no]records |
Affects alignment of derived-type components and fields of record structures. |
|
|
recnbyte |
Specifies a size boundary for derived-type components and fields of record structures. |
|
|
[no]sequence |
Affects alignment of sequenced derived-type components. |
|
|
all |
Adds padding bytes whenever possible to data items in common blocks and structures. |
|
nocommons |
Adds no padding bytes for alignment of common blocks. |
|
nodcommmons |
Adds no padding bytes for alignment of common blocks. |
|
records |
Aligns derived-type components and record structure fields on default natural boundaries. |
|
rec16byte |
Aligns derived-type components and record structure fields on size boundary 16. |
|
nosequence |
Causes derived-type components declared with the SEQUENCE statement to be packed, regardless of current alignment rules set by the user. |
By default, no padding is added to common blocks but padding is added to structures.
This option specifies the alignment to use for certain data items. The compiler adds padding bytes to perform the alignment.
Option |
Description |
|---|---|
| align none | Tells the compiler not to add padding bytes anywhere in common blocks or structures. This is the same as specifying noalign. |
| align commons | Aligns all common block entities on natural boundaries
up to 4 bytes, by adding padding bytes as needed.
The align nocommons option adds no padding to common blocks. In this case, unaligned data can occur unless the order of data items specified in the COMMON statement places the largest numeric data item first, followed by the next largest numeric data (and so on), followed by any character data. |
| align dcommons | Aligns all common block entities on natural boundaries
up to 8 bytes, by adding padding bytes as needed.
This option is useful for applications that use common blocks, unless your application has no unaligned data or, if the application might have unaligned data, all data items are four bytes or smaller. For applications that use common blocks where all data items are four bytes or smaller, you can specify /align:commons instead of /align:dcommons. The align nodcommons option adds no padding to common blocks. On Windows systems, if you specify the /stand:f90 or /stand:f95 option, /align:dcommons is ignored. On Linux systems, if you specify any -std option or the -stand f90 or -stand f95 option, -align dcommons is ignored. |
| align norecords | Aligns components of derived types and fields within record
structures on arbitrary byte boundaries with no padding.
The align records option requests that multiple data items in record structures and derived-type structures without the SEQUENCE statement be naturally aligned, by adding padding as needed. |
| align recnbyte | Aligns components of derived types and fields within record
structures on the smaller of the size boundary specified (n) or the boundary that will naturally
align them. n can be 1, 2, 4,
8, or 16. When you specify this option, each structure member after the
first is stored on either the size of the member type or n-byte boundaries, whichever is
smaller. For example, to specify 2 bytes as the packing boundary (or alignment
constraint) for all structures and unions in the file prog1.f, use the
following command:
ifort {-align rec2byte | /align:rec2byte} prog1.f This option does not affect whether common blocks are naturally aligned or packed. |
| align sequence | Aligns components of a derived type declared with the SEQUENCE
statement (sequenced components) according to the alignment rules that
are currently in use. The default alignment rules are to align unsequenced
components on natural boundaries.
The align nosequence option requests that sequenced components be packed regardless of any other alignment rules. Note that align none implies align nosequence. On Windows systems, if you specify the /stand:f90 or /stand:f95 option, /align:sequence is ignored. On Linux systems, if you specify any -std option or the -stand f90 or -stand f95 option, -align sequence is ignored. |
| align all | Tells the compiler to add padding bytes whenever possible to obtain the natural alignment of data items in common blocks, derived types, and record structures. Specifies align nocommons, align dcommons, align records, align nosequence. This is the same as specifying align with no keyword. |
| align none | Linux: -noalign Windows: /noalign |
|
align records |
Linux: -align rec16byte, -Zp16 |
|
align norecords |
Linux: -Zp1, -align rec1byte |
|
align recnbyte |
Linux: -Zp{1|2|4|8|16} |
|
align all |
Linux: -align commons -align dcommons -align records
-align nosequence |
Optimizing Applications: Setting Data Type and Alignment