Halide test for error behavior when ulimits prevent sufficient memory allocation

ulimit_out_of_memory.cpp

// NOTE: these setrlimit APIs are not implemented in OS X. This should only actually catch failure on Linux.
// TODO: also test overflow on output, intermediate allocations

#include <Halide.h>
#include <stdio.h>
#include <sys/resource.h>

using namespace Halide;

size_t memory_limit_bytes = 1024*1024*128; // 128MB - plenty for Halide, not enough for buffers
int test_width = memory_limit_bytes/4; // In floats, this should be enough memory to overflow on input

int main(int argc, char **argv) {
    // Set limits on core, address space as done by OpenTuner
    rlimit core = {1,1},
             as = {memory_limit_bytes, memory_limit_bytes};
    setrlimit(RLIMIT_CORE, &core);
    setrlimit(RLIMIT_AS,   &as);
    
    fprintf(stderr, "Construct pipeline...");
    Func f;
    ImageParam input(Float(32), 1);
    f(_) = input(_)*2.0f;
    fprintf(stderr, "done\n");

    fprintf(stderr, "Compile...");
    f.compile_jit();
    fprintf(stderr, "done\n");
    
    fprintf(stderr, "Allocate inputs...");
    f.infer_input_bounds(test_width);
    fprintf(stderr, "done\n");
    
    // Dig out the allocation
    Buffer inbuf = input.parameter().get_buffer();
    float* host = (float*)inbuf.host_ptr();
    fprintf(stderr, "Buffer @ %p: %d -> %d\n", inbuf.host_ptr(), inbuf.min(0), inbuf.extent(0));
    
#if 0 // this segfaults, as expected
    fprintf(stderr, "Host[0] = %f\n", host[0]);
#else // this doesn't!
    fprintf(stderr, "Realize...");
    f.realize(test_width);
    fprintf(stderr, "done!\n");
#endif
}