Loop distribution

The loop distribution transformation cuts the body of a do-loop statement in two parts. The first statement of the second part specifies the cut position. For example, the following describes a loop distribution according to the statement I3:

$\vartriangleright$ Example 62: 

  DO I=1,N,4 
    PRINT *,I 
    PRINT *,I+1 
    PRINT *,I+2 
    PRINT *,I+3 
  END DO

$\longrightarrow$

  DO I=1,N
    PRINT *,I
    PRINT *,I+1   
  END DO   
  DO I=1,N 
    PRINT *,I+2 
    PRINT *,I+3 
  END DO

  $\blacktriangleright$ Fits:Distribute:Check(LOOP,DIAGMESG,STAT)

 
This functions check if the loop distribution transformation can be applied to LOOP.

• LOOP (input AST) must be a do-loop statement.
• DIAGMESG (output STRING) is the diagnostic string
• STAT (input AST) must be a statement in the body of LOOP.
• The function returns an error code (return INT):
  • 1 if all is correct
  • 0 if LOOP is not a do-loop statement
  • -1 if STAT is not a statement in the body of LOOP
  • -2 if LOOP contains statements not handled by the transformation.

  $\blacktriangleright$ Fits:Distribute:Advice(LOOP,DIAGMESG,STAT)

 
This function emits a diagnostic about the interest of the loop distribution transformation

• LOOP (input AST) must be a do-loop statement.
• DIAGMESG (output STRING) is a diagnostic string for the user
• STAT (input AST) must be a statement in a do-loop body.
• The function returns a diagnostic code (return INT) :
  • 1 if the transformation is recommended
  • 0 if the transformation may be interesting
  • -1 if the transformation in not recommended

  $\blacktriangleright$ Fits:Distribute:Safe(LOOP,DIAGMESG,STAT)

 
This function emits a diagnostic about the code produced by the loop distribution transformation

• LOOP (input AST) must be a do-loop statement.
• DIAGMESG (output STRING) is the diagnostic string
• STAT (input AST) must be a statement in a do-loop body.
• The function returns a diagnostic code (return INT) :
  • 1 if the transformation is safe
  • 0 if the transformation may be safe. More information are given by the text in DIAGMESG.
  • -1 if the transformation is not safe

  $\blacktriangleright$ Fits:Distribute:Apply(LOOP,VERBOSE,STAT)

 
This function applies the loop distribution transformation.

• LOOP (input AST) must be a do-loop statement.
• VERBOSE (input INT) is the comment level
• STAT (input AST) must be a statement in the body of LOOP
• The function returns the first do-loop statement created by the transformation (return AST).