[cfe-dev] [LLVMdev] OpenCL support

[Anton Lokhmotov]

> Also, don't forget there is a difference between local int a and local
> int* a, one is just a pointer to some pre-allocated memory and the
> other actually requires memory to be allocated.
Correct.

> Any implementation should ignore local pointers variables and only deal
> with local scalar, vector and array variables.
Sorry, I'm not sure what do you mean by this.

int f()
{
    int * __local p; // __local pointer to __private memory
    __local int * p; // __private pointer to __local memory
}

Both examples seem reasonable to me.


> [Villmow, Micah] A kernel with locally defined variables cannot call
> another kernel with local variables. This is illegal in OpenCL because
> when a kernel calls another kernel, that kernel is treated as a normal
> function. A normal function is not allowed to have local variables
> declared inside the body. Basically this restricts locally defined
> variables in a kernel body to the top level kernel function only.
This sounds reasonable, but, to be precise, the specification says: "The
behavior of calling kernel functions with variables declared inside the
function with the __local or local qualifier from other kernel functions is
implementation-defined."  In principle, an implementation can statically
compute the call graph of the kernel function being compiled and conflate
local memory allocation requirements from different kernel functions in the
graph...

Regards,
Anton.