[all-commits] [llvm/llvm-project] 19841e: [OpenMP] Fix transformed loop's var privacy

Joel E. Denny via All-commits all-commits at lists.llvm.org
Fri Jun 2 09:19:43 PDT 2023

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 19841e4dcaabe573d35eb88a130fc34d32ecd708
  Author: Joel E. Denny <jdenny.ornl at gmail.com>
  Date:   2023-06-02 (Fri, 02 Jun 2023)

  Changed paths:
    M clang/lib/Sema/SemaOpenMP.cpp
    M clang/test/OpenMP/unroll_codegen_parallel_for_factor.cpp
    A openmp/libomptarget/test/offloading/target-tile.c

  Log Message:
  [OpenMP] Fix transformed loop's var privacy

Without this patch, the following example crashes Clang:

 #pragma omp target map(i)
 #pragma omp tile sizes(2)
 for (i = 0; i < N; ++i)

This patch fixes the crash by changing `Sema::isOpenMPPrivateDecl` not
to identify `i` as private just because it's the loop variable of a
`tile` construct.

While OpenMP TR11 and earlier do specify privacy for loop variables of
loops *generated* from a `tile` construct, I haven't found text
stating that the original loop variable must be private in the above
example, so this patch leaves it shared.  Even so, it is a bit
unexpected that value of `i` after the loop is `N - 1` instead of `N`.

Reviewed By: ABataev

Differential Revision: https://reviews.llvm.org/D151356

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