test case of a gcc issue

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>



void f(const uint32_t* image_bgra, int H, int W,
        float* out,
        int margin)
{

    const int mu = margin;
    const int md = margin;
    const int mr = margin;
    const int ml = margin;
    //const int ml = 3;

    printf("params: H=%d W=%d, ml%d mr%d mu%d md%d\n", H, W, ml, mr, mu, md);

    for(int y=0; y<H; y++) {
        for(int x=0; x<W; x++) {
            const int idx = x + W*y;

            if ((y < mu)  || (y >= H - md) ||
                    (x < ml)  || (x >= W - mr)) {

                out[idx + H*W*0] = 0.0f;
                out[idx + H*W*1] = 0.0f;
                out[idx + H*W*2] = 0.0f;
                out[idx + H*W*3] = 0.0f;

            } else {
                out[idx + H*W*0] = 1.0;
                out[idx + H*W*1] = 2.0;
                out[idx + H*W*2] = 3.0;
                out[idx + H*W*3] = 4.0;

            }
            if (x==0) {
                printf("out(x = %d ,y = %d, idx = %d , H = %d, W = %d) = %.f.\n",x,y,idx,H,W,out[idx + H*W*0]);
            }

        }
    }

    for (int y = 0; y < H; y++) {
        if (out[W*y] > 0.0f) {
            printf ("This shouldn't be seen: Line %d, value = %f\n", y, out[W*y]);
        }
    }

    return;
}






int main ()
{
    const int H = 42;
    const int W = 32;
    const int D = 4;



    float* out2 = (float*) malloc(H * W * D * sizeof(float));


    f(NULL, H, W,
            out2,
            3);


    return 0;
}