[Openmp-commits] [openmp] [OpenMP] Fix td_tdg_task_id underflow when taskloop and taskgraph (PR #150877)

[Josep Pinot via Openmp-commits]

jpinot wrote:

> Right, I missed, that record_map is essentially of type `vector<kmp_node_info_t>`, not `vector<kmp_node_info_t *>`.
> 
> Another possible approach would be to use a customized vector which allocates `fixed_sized` blocks as necessary (instead of realloc) and redirects `operator[](i)` to look at the `i % fixed_sized` element of block `i / fixed_sized`.

I have pushed a WIP commit with the changes discussed. However, a data race occurs when thread A reallocates blocks (the array of `blocks`; note that the actual blocks are never resized) to increase the number of blocks, and thread B calls  [kmp_node_vector_get](https://github.com/llvm/llvm-project/pull/150877/commits/b151a84f336838f5bdc0f41b1c2798fd2f3fe22e#diff-8402e656316eb873d5db4dea7f697406d15ae4197dcc60d88b3d9fc252fcb69aR5377) to access an existing node. The returned pointer points to invalid data. I suspect this could be due to a compiler optimization or an issue with the return value handling(?).

@jprotze, do you know what might be causing this?

https://github.com/llvm/llvm-project/pull/150877