GNU libgomp: Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses

Next: Implementing REDUCTION clause, Previous: Implementing PRIVATE clause, Up: The libgomp ABI [Contents][Index]

### 9.8 Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses

This seems simple enough for PARALLEL blocks. Create a private struct for communicating between the parent and subfunction. In the parent, copy in values for scalar and "small" structs; copy in addresses for others TREE_ADDRESSABLE types. In the subfunction, copy the value into the local variable.

It is not clear what to do with bare FOR or SECTION blocks. The only thing I can figure is that we do something like:

    #pragma omp for firstprivate(x) lastprivate(y)
    for (int i = 0; i < n; ++i)
      body;

which becomes

    {
      int x = x, y;

      // for stuff

      if (i == n)
        y = y;
    }

where the "x=x" and "y=y" assignments actually have different uids for the two variables, i.e. not something you could write directly in C. Presumably this only makes sense if the "outer" x and y are global variables.

COPYPRIVATE would work the same way, except the structure broadcast would have to happen via SINGLE machinery instead.