fdvmLDe (1158336), страница 12
Текст из файла (страница 12)
| alignee | is array-name |
| or pointer-name |
| align-source | is * |
| or align-dummy |
| align-dummy | is scalar-int-variable |
| align-with-clause | is WITH align-spec |
| align-spec | is align-target ( align-subscript-list ) |
| align-target | is array-name |
| or template-name | |
| or pointer-name |
| align-subscript | is int-expr |
| or align-dummy-use | |
| or * |
| align-dummy-use | is [ primary-expr * ] align‑dummy |
| primary-expr | is int-constant |
| or int-variable | |
| or ( int-expr ) | |
| add-op | is + |
| or - |
Constraints:
-
A length of align-source-list must be equal to the rank of aligned array.
-
A length of align-subscript-list must be equal to the rank of align‑target.
-
Each align-dummy may appear at most once in an align-subscript-list.
-
An array-name mentioned as an alignee may not appear as a distributee.
-
REALIGN directive may be applied only to the arrays specified in DYNAMIC directives.
-
align-directive-stuff can be omitted only in ALIGN directive. In such a case the distributed array can be used only after execution of REALIGN directive.
4.3.2. TEMPLATE directive
| template-directive | is TEMPLATE template-decl-list |
| template-decl | is template-name [ ( explicit-shape-spec-list ) ] |
4.4. DYNAMIC and NEW_VALUE directives
| dynamic-directive | is DYNAMIC alignee-or-distributee-list |
| alignee-or-distributee | is alignee |
| or distributee | |
| new-value-directive | is NEW_VALUE |
5.1.2. Distribution of loop iterations. PARALLEL directive
| parallel-directive | is PARALLEL ( do-variable-list ) | |
| iteration-align-spec | is align-target ( iteration-align-subscript-list ) | |
| iteration-align-subscript | is int-expr |
| or do-variable-use | |
| or * | |
| do-variable-use | is [ primary-expr * ] do-variable [ add-op primary-expr] |
5.1.3. Private variables. NEW clause
| new-clause | is NEW ( new-variable-list ) |
| new-variable | is array-name |
| or scalar-variable-name |
Constraint:
-
The distributed arrays cannot be used as NEW-variables.
5.1.4. Reduction operations and variables. REDUCTION clause
| reduction-clause | is REDUCTION |
| reduction-op | is reduction-op-name ( reduction-variable ) |
| or reduction-loc-name ( reduction-variable , |
| reduction-variable | is array-name |
| or scalar-variable-name |
| location-variable | is array-name |
| reduction-op-name | is SUM |
| or PRODUCT | |
| or MAX | |
| or MIN | |
| or AND | |
| or OR | |
| or EQV | |
| or NEQV |
| reduction-loc-name | is MAXLOC |
| or MINLOC |
Constraints:
-
Distributed arrays cannot be used as reduction variables.
-
Reduction variables are calculated and used only inside the loop in statements of a certain type: the reduction statements.
6.2.1. Specification of array with shadow edges
| shadow-directive | is SHADOW dist-array ( shadow-edge-list ) |
| or SHADOW ( shadow-edge-list ) :: dist-array-list |
| dist-array | is array-name |
| or pointer-name |
| shadow-edge | is width |
| or low-width : high-width |
| width | is int-expr |
| low-width | is int-expr |
| high-width | is int-expr |
Constraints:
-
The int-expr representing a width, low-width, or high-width must be a constant specification expression with value greater than or equal to 0.
-
A shadow-edge specification of width is equivalent to a shadow-edge of width : width.
-
By default distributed array has a shadow width of 1 on both sides of each distributed dimension.
6.2.2. Synchronous specification of independent references of SHADOW type for
single loop
| shadow-renew-clause | is SHADOW_RENEW ( renewee‑list ) |
| or shadow-start-directive | |
| or shadow-wait-directive |
| renewee | is dist-array-name [ ( shadow-edge-list )] [ (CORNER) ] |
Constraints:
-
Width of the shadow edges filled by values must not exceed the maximal width specified in the SHADOW directive.
-
If shadow edge widths is not specified, then the maximal widths are used.
6.2.3. Computing values in shadow edges. SHADOW_COMPUTE clause
| shadow-compute-clause | is SHADOW_COMPUTE |
6.2.4. ACROSS specification of dependent references of SHADOW type for single loop
| across-clause | is ACROSS ( dependent-array-list ) |
| dependent-array | is dist-array-name ( dependence-list ) [(section-spec-list)] |
| dependence | is flow-dep-length : anti-dep-length |
| flow-dep-length | is int-constant |
| anti-dep-length | is int-constant |
| section-spec | is SECTION (section-subscript-list) |
Constraint:
-
In each array reference, data dependence may appear only in one distributed dimension.
6.2.5. Asynchronous specification of independent references of SHADOW type
| shadow-group-directive | is SHADOW_GROUP shadow-group-name |
| shadow-start-directive | is SHADOW_START shadow-group-name |
| shadow-wait-directive | is SHADOW_WAIT shadow-group-name |
Constraints:
-
SHADOW_START directive must be executed after SHADOW_GROUP one.
-
SHADOW_WAIT directive must be executed after SHADOW_START one.
-
Updated values of the shadow edges may be used only after SHADOW_WAIT directive.
-
These directives may not be used within a parallel loop.
6.3.1. REMOTE_ACCESS directive
| remote-access-directive | is REMOTE_ACCESS |
| regular-reference | is dist-array-name [( regular-subscript-list )] |
| regular-subscript | is int-expr |
| or do-variable-use | |
| or : | |
| remote-access-clause | is remote-access-directive |
6.3.3. Asynchronous specification of REMOTE type references
| remote-group-directive | is REMOTE_GROUP remote-group-name-list |
Constraint:
-
The identifier, specified in the directive, can be used only in REMOTE_ACCESS, PREFETCH and RESET directives.
| prefetch-directive | is PREFETCH remote-group-name |
| reset-directive | is RESET remote-group-name |
Constraints:
-
Repeated usage of PREFETCH directive is correct, if the remote reference group characteristics (the loop parameters, distribution of arrays and the values of index expressions in remote references) are not updated.
-
PREFETCH directive can be executed for the several loops (several REMOTE_ACCESS directives), if there are no data dependencies between the loops for distributed arrays specified in the REMOTE_ACCESS directives.
6.3.4.2.1. ASYNCID directive
| asyncid-directive | is ASYNCID async-name-list |
6.3.4.2.2. F90 directive
| f90-directive | is F90 copy-statement |
| copy-statement | is array-section = array-section |
| array-section | is array-name [ ( section-subscript-list ) ] |
| section-subscript | is subscript |
| or subscript-triplet | |
| subscript-triplet | is [ subscript ] : [ subscript ] [ : stride] |
| subscript | is int-expr |
| stride | is int-expr |
6.3.4.2.3. ASYNCHRONOUS and END ASYNCHRONOUS directives
| asynchronous-construct | is asynchronous-directive |
| f90-directive [ f90-directive ] … copy-loop [ copy-loop ] … | |
| end-asynchronous-directive | |
| asynchronous-directive | is ASYNCHRONOUS async-name |
| end-asynchronous-directive | is END ASYNCHRONOUS |
6.3.4.2.4. ASYNCWAIT directive
| asyncwait-directive | is ASYNCWAIT async-name |
6.4.2. Asynchronous specification of REDUCTION type references
| reduction-group-directive | is REDUCTION_GROUP reduction-group-name-list |
| reduction-start-directive | is REDUCTION_START reduction-group-name |
| reduction-wait-directive | is REDUCTION_WAIT reduction-group-name |
Constraints:
-
Before executing REDUCTION_START directive, the reduction variables of the group may be used in reduction statements of parallel loops only.
-
REDUCTION_START and REDUCTION_WAIT directives must be executed after the completion of the loop (loops) where the values of the reduction variables are calculated. The only statements allowed between these directives are those that are not using the values of the reduction variables.
-
REDUCTION_WAIT directive deletes the group of the reduction operations.
7.1. Declaration of task array
| task-directive | is TASK task-list |
| task | is task-name ( max-task ) |
7.2. Mapping tasks on processors. MAP directive
| map-directive | is MAP task-name ( task-index ) |
| ONTO processors-name(processors-section-subscript-list) |
7.4. Distribution of computations. TASK_REGION directive
| block-task-region | is task-region-directive | |
| on-block | ||
| [ on-block ]... | ||
| end-task-region-directive | ||
| task-region-directive | is TASK_REGION task-name [ , reduction-clause ] | |
| end-task-region-directive | is END TASK_REGION | |
| on-block | is on-directive | |
| block | ||
| end-on-directive | ||
| on-directive | is ON task-name ( task-index ) [ , new-clause ] | |
| end-on-directive | is END ON | |
| loop-task-region | is task-region-directive | |
| parallel-task-loop | ||
| end-task-region-directive | ||
| parallel-task-loop | is parallel-task-loop-directive | |
| do-loop | ||
| parallel-task-loop-directive | is PARALLEL ( do-variable ) | |
9. Procedures
| inherit-directive | is INHERIT dummy-array-name-list |
Annex2. Code examples
Seven small scientific programs are presented to illustrate Fortran DVM language features. They are intended for solving a system of linear equations:
![](https://s.studizba.com/z.php?f=/templates/si/i/noavatar.png&w=100&h=100&t=1"){kind=avatar}
