[gomp4 11/14] libgomp: avoid variable-length stack allocation in team.c

[Bernd Schmidt]

On 10/20/2015 08:34 PM, Alexander Monakov wrote:
> NVPTX does not support alloca or variable-length stack allocations, thus
> heap allocation needs to be used instead.  I've opted to make this a generic
> change instead of guarding it with an #ifdef: libgomp usually leaves thread
> stack size up to libc, so avoiding unbounded stack allocation makes sense.
>
> 	* task.c (GOMP_task): Use a fixed-size on-stack buffer or a heap
>          allocation instead of a variable-size on-stack allocation.

> +	  char buf_fixed[2048], *buf = buf_fixed;

This might also not be the best of ideas on a GPU - the stack size isn't 
all that unlimited, what with there being lots of threads. If I do

   size_t stack, heap;
   cuCtxGetLimit (&stack, CU_LIMIT_STACK_SIZE);

in the nvptx-run program we've used for testing, it shows a default 
stack size of just 1kB.


Bernd