Attributes for data dependencies

A set of attributes have also been implemented in order to provide an access to data dependencies. These one rely on the usual notation to access to the various kind of dependencies which are the following:

• direct dependencies (also named read after write);
• anti dependencies (write after read);
• output dependencies (write after write);
• control dependencies, point out the statements whose the execution depends on the evaluation of an expression;
• value dependencies, point out the reuse of the variables.

In TSF, access to data dependencies requires two steps:

• first you need to create a DepObjectList object. This object which belong to the set of objects whose type is not documented, gather all the dependencies computed from a statement.
• second, you access to a particular dependency (that we will call a DepObject) by going over the DepObjectList object and by displaying useful information.

The following attributes are provided:

  $\blacktriangleright$ stat.DEP()

 
  This attribute returns the dependencies list computed from the current statement. This list is returned under the form of an undocumented type that we call a DepObjectList. A DepObjectList is a list of objects of the type DepObject which designate a data dependency. By default, the direct, anti and output dependencies are taken into account if no argument is provided. Otherwise, the following possibilities are also provided:

$\vartriangleright$ Example 49: 

    depList        := currentStat.DEP() // by default get all the direct, anti
    and output dependencies
    directDepList  := currentStat.DEP(DIRECT)  
    antiDepList    := currentStat.DEP(ANTI)    
    outputDepList  := currentStat.DEP(OUT)     
    valueDepList   := currentStat.DEP(VALUE)   
    controlDEpList :=  currentStat.DEP(CONTROL)
    directAndAntiDepList   := currentStat.DEP(DIRECT,ANTI)
    directAndOutputDepList := currentStat.DEP(DIRECT,OUT)

as well as all the other combinations.

The predefined keywords DIRECT, ANTI, OUT, VALUE, CONTROL may be replaced directly by their corresponding values ("direct", "anti", "out", "value", "control").

  $\blacktriangleright$ depObjectList.NBDEP()

 
  This attribute returns the number of dependencies contained in the current depObjectList object.

  $\blacktriangleright$ depObjectList.NBDEP(n)

 
Return the n^th depObject contained in the depObjectList object.

  $\blacktriangleright$ depObject.SOURCE

 
  Return the source statement of the considered dependency.

  $\blacktriangleright$ depObject.SOURCEEXPR

 
  Return the source expression involved in the considered dependency.

  $\blacktriangleright$ depObject.DESTINATION

 
  Return the destination statement of the considered dependency.

  $\blacktriangleright$ depObject.DESTINATIONEXPR

 
  Return the destination expression involved in the considered dependency.

  $\blacktriangleright$ depObject.KIND

 
  Return the kind of the considered dependency. Kinds returned are: direct, anti, out, value, control and are of type string.

  $\blacktriangleright$ depObject.DISTANCEVECTOR

 
  Return the whole distance vector of the considered dependency. This distance vector is given from the most internal loop to the most external loop.

  $\blacktriangleright$ depObject.DISTVECTORSIZE()

 
  Return the size of the current distance vector.

  $\blacktriangleright$ depObject.DISTVECTORSIZE(n)

 
Return the n^th component of the current distance vector.

$\vartriangleright$ Example 50:Example on the manipulation of the data dependencies.

Script
SCRIPT DisplayOutputDependence () outputDep := $cstat.DEP(OUT) // Get just the output data dependencies nbOutputDep := outputDep.NBDEP() // Number of output data dependencies it := 1 // Iterator WHILE (it <= nbOutputDep) // Go over all the output data dependencies PRINT "Kind of the dataDep: " + outputDep.NBDEP(it).KIND // (P1) Kind of the data dependency PRINT "SOURCE" PRINT outputDep.NBDEP(it).SOURCEEXPR // (P2) Source expression of the current data dependency PRINT outputDep.NBDEP(it).SOURCE // (P3) Source statement of the current data dependency PRINT "DESTINATION" PRINT outputDep.NBDEP(it).DESTINATIONEXPR    // (P4) Destination expression of the current data dep. PRINT outputDep.NBDEP(it).DESTINATION // (P5) Destination statement of the current data dep. PRINT outputDep.NBDEP(it).DISTANCEVECTOR // (P6) Distance vector // (from the most internal loop to the most external loop) // Now deal with each component of the distance vector vectorSize := outputDep.NBDEP(it).DISTVECTORSIZE() // Get the size of the distance vector vectorIt := 1 // Iterator WHILE (vectorIt <= vectorSize) // Go over all the components of the distance vector value := outputDep.NBDEP(it).DISTVECTORSIZE(vectorIt) // Get the component PRINT "component " + TOSTRING(vectorIt) + ": " + TOSTRING(value) // (P7) Print its value // PRINT outputDep.NBDEP(it).DISTVECTORSIZE(vectorIt) // // value of the component (ex. >=) vectorIt := vectorIt +1 // Go to the next component of the distance vector ENDWHILE it := it + 1 // Go to the next data dependency ENDWHILE ENDSCRIPT
Fortran User Selection	Results
do 430 i = 1,nsize1 do 440 j = 1,nsize2 s = s + a2(j,i) 440 continue 430 continue	P1 : Kind of the dataDep: out SOURCE P2 : s P3 : s = s + a2(j,i) DESTINATION P4 : s P5: s = s + a2(j,i) P6 : (1 0) P7 : component 1: 1 P7 : component 2: 0	P1 : Kind of the dataDep: out SOURCE P2 : s P3 : s = s + a2(j,i) DESTINATION P4 : s P5 : s = s + a2(j,i) P6 : (0 >) P7 : component 1: 0 P7 : component 2: >