#47 bug using branching and integer values for indexing gather

[Ramandeep Singh Bhatia]

/*
vSrc = {
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0
8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 }

vInd = {
-10 -9 6 -11 7 5 -3 13
2 4 13 -12 6 9 9 1 }

- Positive indirections copy the data from vSrc using the indirection.
- Negative indirections copy the data from vSrc directly.
- The output is marked adding 0.1f or 0.2f to know the taken path.

Right output using "if(ins >= 0) dst = ..."
vOut = {
0.1 1.1 6.2 3.1 7.2 5.2 6.1 13.2
2.2 4.2 13.2 11.1 6.2 9.2 9.2 1.2 }

Wrong output using "else dst = ..."
vOut = {
0.1 1.1 4.2 3.1 4.2 4.2 6.1 12.2
2.2 4.2 12.2 11.1 6.2 9.2 8.2 0.2 }
*/

// Prints a float array
void vfprint(const char *name, const float *v, const int len) {
int i;
printf("%s = { ", name);
for(i = 0; i < len; i++)
if(!(i & 0x07)) printf("\n %4.1f ", v[i ]);
else printf("%4.1f ", v[i ]);
printf("}\n");
}

// Prints a int array
void viprint(const char *name, const int *v, const int len) {
int i;
printf("%s = { ", name);
for(i = 0; i < len; i++)
if(!(i & 0x07)) printf("\n %4i ", v[i ]);
else printf("%4i ", v[i ]);
printf("}\n");
}

kernel void
KBUG(float src[][], int ins<>, out float dst<>, int DIMX)
{
// Convertimos coordenadas 2D a 1D
int2 pos2D = instance().xy;
// int pos = pos2D.x + DIMX * pos2D.y;

int2 ins2D;
ins2D.y = (int)floor((float)ins / (float)DIMX);
ins2D.x = ins - ins2D.y * DIMX;

if(ins < 0) dst = src[pos2D.y][pos2D.x] + 0.1f;
// if(ins >= 0) dst = src[ins2D.y][ins2D.x] + 0.2f; // <--- *** THIS WORKS OK ***
else dst = src[ins2D.y][ins2D.x] + 0.2f; // <--- *** THIS FAILS ***
}

int main(int argc, char* argv[ ] ) {
// Test size
const int SIZE_X = 4;
const int SIZE_Y = 4;
const int SIZE = SIZE_X * SIZE_Y;

// CPU arrays
float vSrc[SIZE];
int vInd[SIZE];
float vOut[SIZE];

// Init
int i;
srand(0);
for(i = 0; i < SIZE; i++) {
vSrc[i ] = (float)i;
vInd[i ] = (rand() % 32) - 16;
vOut[i ] = 0;
}

{
// Stream arrays
float sSrc<SIZE_Y, SIZE_X>;
int sInd<SIZE_Y, SIZE_X>;
float sOut<SIZE_Y, SIZE_X>;

// Load
streamRead(sSrc, vSrc);
streamRead(sInd, vInd);

// Launch kernel
KBUG(sSrc, sInd, sOut, SIZE_X);

// Write
streamWrite(sOut, vOut);
}

// Print output
vfprint("vSrc", vSrc, SIZE);
viprint("vInd", vInd, SIZE);
vfprint("vOut", vOut, SIZE);

return 0;
}

Brook 1.4, Catalyst 9.8, Radeon 4850, WinXP x64, MSVC 2005

[Gaurav Garg]

Forum URL:
http://forums.amd.com/forum/messageview.cfm?catid=328&threadid=118262&forumid=9