Output Converter

Overview

The output converter converts foralls into DO loops, handles allocate and deallocate statements, and optimizes array descriptor handling.

Data Structures

Global Data Structures

.uh “Symbol Table” The symbol table is accessed. .uh “AST” Statements are inserted and deleted.

Local Data Structures

There are no significant local data structures in the Output Converter.

Processing

Overview

The main entry point to the output converter is convert_output(). It calls convert_forall() to convert forall statements and allocate/deallocate statements. It then calls transform_wrapup() to output descriptor information.

Forall Conversion

This task is performed by conv_forall(). One DO loop is created for each forall index, and the forall statement is converted to a comment. No dependence checking is done; currently it is assumed that earlier phases have removed any dependences that prevent simple conversion to DO loops.

Mask expressions are converted to IF statements inside the loop.

Forall conversion will likely be changed in a future release to perform more optimal scalarization, loop fusions, etc.

Allocate/Deallocate

Allocate and deallocate statements are handled by conv_allocate and conv_deallocate. If necessary, descriptors are created and initialized. It may also be necessary to initialize the array bounds variables if a deferred-shape array is allocated.

Descriptors

transform_wrapup() is contained in the file dpm_out.c. It loops over each entry point in the subprogram, and performs the following tasks:

1. Transform arguments to support the Fotran calling convention.

2. Initialize processor and template descriptors.

3. Perform copy_in and copy_out on array arguments.

4. Initialize common blocks.

5. Create alignment and distribution descriptors.

6. Allocate distributed array sections.

The program return statement is preceeded by statements to free the descriptors, local arrays, and so forth.