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| <h3 class="section">4.8 Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses</h3> |
| |
| <p>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. |
| </p> |
| <p>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: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">#pragma omp for firstprivate(x) lastprivate(y) |
| for (int i = 0; i < n; ++i) |
| body; |
| </pre></div> |
| |
| <p>which becomes |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">{ |
| int x = x, y; |
| |
| // for stuff |
| |
| if (i == n) |
| y = y; |
| } |
| </pre></div> |
| |
| <p>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. |
| </p> |
| <p>COPYPRIVATE would work the same way, except the structure |
| broadcast would have to happen via SINGLE machinery instead. |
| </p> |
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