ispc/examples/stencil/stencil.cpp

/*
  Copyright (c) 2010-2011, Intel Corporation
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      notice, this list of conditions and the following disclaimer in the
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    * Neither the name of Intel Corporation nor the names of its
      contributors may be used to endorse or promote products derived from
      this software without specific prior written permission.


   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
   IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
   PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
   OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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*/

#ifdef _MSC_VER
#define _CRT_SECURE_NO_WARNINGS
#define NOMINMAX
#pragma warning (disable: 4244)
#pragma warning (disable: 4305)
#endif

#include <stdio.h>
#include <algorithm>
#include <string.h>
#include <math.h>
#include "../timing.h"
#include "stencil_ispc.h"
using namespace ispc;


extern void loop_stencil_serial(int t0, int t1, int x0, int x1,
                                int y0, int y1, int z0, int z1,
                                int Nx, int Ny, int Nz,
                                const float coef[5], 
                                const float vsq[],
                                float Aeven[], float Aodd[]);


void InitData(int Nx, int Ny, int Nz, float *A[2], float *vsq) {
    int offset = 0;
    for (int z = 0; z < Nz; ++z)
        for (int y = 0; y < Ny; ++y)
            for (int x = 0; x < Nx; ++x, ++offset) {
                A[0][offset] = (x < Nx / 2) ? x / float(Nx) : y / float(Ny);
                A[1][offset] = 0;
                vsq[offset] = x*y*z / float(Nx * Ny * Nz);
            }
}


int main(int argc, char *argv[]) {
    static unsigned int test_iterations[] = {3, 3, 3};//the last two numbers must be equal here
    int Nx = 256, Ny = 256, Nz = 256;
    int width = 4;

    if (argc > 1) {
        if (strncmp(argv[1], "--scale=", 8) == 0) {
            float scale = atof(argv[1] + 8);
            Nx *= scale;
            Ny *= scale;
            Nz *= scale;
        }
    }
    if ((argc == 4) || (argc == 5)) {
        for (int i = 0; i < 3; i++) {
            test_iterations[i] = atoi(argv[argc - 3 + i]);
        }
    }

    float *Aserial[2], *Aispc[2];
    Aserial[0] = new float [Nx * Ny * Nz];
    Aserial[1] = new float [Nx * Ny * Nz];
    Aispc[0] = new float [Nx * Ny * Nz];
    Aispc[1] = new float [Nx * Ny * Nz];
    float *vsq = new float [Nx * Ny * Nz];

    float coeff[4] = { 0.5, -.25, .125, -.0625 }; 

    InitData(Nx, Ny, Nz, Aispc, vsq);
    //
    // Compute the image using the ispc implementation on one core; report
    // the minimum time of three runs.
    //
    double minTimeISPC = 1e30;
    for (int i = 0; i < test_iterations[0]; ++i) {
        reset_and_start_timer();
        loop_stencil_ispc(0, 6, width, Nx - width, width, Ny - width,
                          width, Nz - width, Nx, Ny, Nz, coeff, vsq,
                          Aispc[0], Aispc[1]);
        double dt = get_elapsed_mcycles();
        printf("@time of ISPC run:\t\t\t[%.3f] million cycles\n", dt);
        minTimeISPC = std::min(minTimeISPC, dt);
    }

    printf("[stencil ispc 1 core]:\t\t[%.3f] million cycles\n", minTimeISPC);

    InitData(Nx, Ny, Nz, Aispc, vsq);

    //
    // Compute the image using the ispc implementation with tasks; report
    // the minimum time of three runs.
    //
    double minTimeISPCTasks = 1e30;
    for (int i = 0; i < test_iterations[1]; ++i) {
        reset_and_start_timer();
        loop_stencil_ispc_tasks(0, 6, width, Nx - width, width, Ny - width,
                                width, Nz - width, Nx, Ny, Nz, coeff, vsq,
                                Aispc[0], Aispc[1]);
        double dt = get_elapsed_mcycles();
        printf("@time of ISPC + TASKS run:\t\t\t[%.3f] million cycles\n", dt);
        minTimeISPCTasks = std::min(minTimeISPCTasks, dt);
    }

    printf("[stencil ispc + tasks]:\t\t[%.3f] million cycles\n", minTimeISPCTasks);

    InitData(Nx, Ny, Nz, Aserial, vsq);

    // 
    // And run the serial implementation 3 times, again reporting the
    // minimum time.
    //
    double minTimeSerial = 1e30;
    for (int i = 0; i < test_iterations[2]; ++i) {
        reset_and_start_timer();
        loop_stencil_serial(0, 6, width, Nx-width, width, Ny - width,
                            width, Nz - width, Nx, Ny, Nz, coeff, vsq,
                            Aserial[0], Aserial[1]);
        double dt = get_elapsed_mcycles();
        printf("@time of serial run:\t\t\t[%.3f] million cycles\n", dt);
        minTimeSerial = std::min(minTimeSerial, dt);
    }

    printf("[stencil serial]:\t\t[%.3f] million cycles\n", minTimeSerial);

    printf("\t\t\t\t(%.2fx speedup from ISPC, %.2fx speedup from ISPC + tasks)\n", 
           minTimeSerial / minTimeISPC, minTimeSerial / minTimeISPCTasks);

    // Check for agreement
    int offset = 0;
    for (int z = 0; z < Nz; ++z)
        for (int y = 0; y < Ny; ++y)
            for (int x = 0; x < Nx; ++x, ++offset) {
                float error = fabsf((Aserial[1][offset] - Aispc[1][offset]) /
                                    Aserial[1][offset]);
                if (error > 1e-4)
                    printf("Error @ (%d,%d,%d): ispc = %f, serial = %f\n",
                           x, y, z, Aispc[1][offset], Aserial[1][offset]);
            }

    return 0;
}