Cache backend symbols in the unified backend

[umar456]

Test code:

#include <arrayfire.h>
#include <cstdio>
#include <cstdlib>
#include <chrono>

using namespace af;

int main(int argc, char *argv[])
{
    try {
      int backends = af::getAvailableBackends();
      af::setBackend(AF_BACKEND_CUDA);
      af::info();

      printf("\nRunning %s...\n", argv[0]);

      for(int i = 500; i < 100000; i+= 500) {
        auto start = std::chrono::high_resolution_clock::now();
        for(int iter = 0; iter < 10000; iter++) {
          af::array blah = af::randu(i);
          af::array constant_val = af::constant(1, i);
          af::array output = dot(blah, constant_val);
        }
        af::sync();
        auto end = std::chrono::high_resolution_clock::now();
        af::deviceGC();
        printf("| %7d | %5llu us |\n", i, std::chrono::duration_cast<std::chrono::microseconds>(end-start).count());
      }
    } catch (af::exception& e) {

        fprintf(stderr, "%s\n", e.what());
        throw;
    }

    return 0;
}

[pavanky]

Does it always return NULL when it is not found ?

[umar456]

I am 96.3% sure it does.

[pavanky]

Move the array outside ?

[umar456]

👍

[pavanky]

Is getActiveBackend returning the enum or is it returning the index ?

[umar456]

oops. It's a flag. Fixing.

[pavanky]

Hmm, we have something called AF_BACKEND_DEFAULT. Please check if it works with that.

[umar456]

The SymbolManager and setBackend function sets the activeBackend to one of those backends.

[pavanky]

@umar456 Alternative suggestion: Instead of querying from an unordered_map each time, can't the function pointer be cached inside the caller function ?

This reduces the lookup time from the map. You will need change the definition of CALL macros.

[umar456]

I tried that first but the call function's template parameters are based on the type of arguments and not the function name itself. I could change the macro so that we only have an array instead of a map but I didn't want to break anything.

I can change it if you think its worthwhile.

[pavanky]

We can still pass the arguments, but instead of calling the function, it will just return the function pointer. The call can be made externally. No reason to cache the symbol inside the call function.

[umar456]

build arrayfire windows ci