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Add additional checks for iq1_s_r4 quantization #191

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Feb 7, 2025
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Add additional checks for iq1_s_r4 quantization #191

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35 changes: 30 additions & 5 deletions ggml/src/iqk/iqk_quantize.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6116,23 +6116,48 @@ size_t quantize_iq1_s_r4(const float * src, void * dst, int64_t nrows, int64_t n
auto y = (block_iq1_s_r4 *)(dptr + 4);
for (int k = 0; k < 4; ++k) max[k] = 0;
for (int ibl = 0; ibl < nblock; ++ibl) {
if (imatrix) {
for (int j = 0; j < kBlockSize; ++j) weight[j] = imatrix[kBlockSize*ibl + j];
}
for (int k = 0; k < 4; ++k) {
auto xb = src + k*n_per_row + kBlockSize*ibl;
float sumx2 = 0;
for (int j = 0; j < kBlockSize; ++j) sumx2 += xb[j]*xb[j];
if (!sumx2) {
printf("Found block with all zeros\n");
// all zero
int ind = 1029; // this is the grid entry with all zeros
scales[4*ibl+k] = 0;
uint16_t h = 0;
for (int i = 0; i < 4; ++i) {
y[ibl].qs[4*i + k] = ind & 255;
h |= (ind >> 8) << 3*i;
}
y[ibl].qh[k] = h;
continue;
}
float sigma2 = 1.5f*sumx2/kBlockSize;
bool have_imatrix = false;
if (imatrix) {
for (int j = 0; j < kBlockSize; ++j) weight[j] = imatrix[kBlockSize*ibl + j]*sqrt(sigma2 + xb[j]*xb[j]);
} else {
have_imatrix = true;
float sumwx = 0;
for (int j = 0; j < kBlockSize; ++j) {
weight[j] = imatrix[kBlockSize*ibl + j]*sqrt(sigma2 + xb[j]*xb[j]);
sumwx += weight[j]*std::abs(xb[j]);
}
if (!sumwx) {
printf("Found block with mismatching importance/model weights\n");
// Either all weights are zero, or xb is zero where weight is not zero.
// In both of these cases it is better to simply ignore the imatrix
have_imatrix = false;
}
}
if (!have_imatrix) {
for (int j = 0; j < kBlockSize; ++j) weight[j] = sqrt(sigma2 + xb[j]*xb[j]);
}
iq1s_process_1block(kBlockSize, xb, weight, L, scales.data() + 4*ibl + k, index, &shift, pairs, sumx, sumw);
GGML_ASSERT(scales[4*ibl+k] >= 0);
max[k] = std::max(max[k], scales[4*ibl+k]);
uint16_t h = 0;
for (int i = 0; i < 4; ++i) {
GGML_ASSERT(index[i] >= 0 && index[i] < 2048);
y[ibl].qs[4*i + k] = index[i] & 255;
h |= (index[i] >> 8) << 3*i;
}
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