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Fix CUDA Multinomial checks #4009

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Merged
soumith merged 1 commit into from
Dec 18, 2017
Merged

Fix CUDA Multinomial checks #4009

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10 changes: 8 additions & 2 deletions aten/src/TH/generic/THTensorRandom.c
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Original file line number Diff line number Diff line change
Expand Up @@ -253,7 +253,7 @@ void THTensor_(multinomial)(THLongTensor *self, THGenerator *_generator, THTenso
THArgCheckWithCleanup(n_sample > 0,
THCleanup(if (start_dim == 1) THTensor_(resize1d)(prob_dist, n_categories);),
2,
"cannot sample n_sample < 0 samples");
"cannot sample n_sample <= 0 samples");

if (!with_replacement)
{
Expand All @@ -273,12 +273,18 @@ void THTensor_(multinomial)(THLongTensor *self, THGenerator *_generator, THTenso
{
/* Get normalized cumulative distribution from prob distribution */
double sum = 0;
double val;
for (j=0; j<n_categories; j++)
{
sum += THStorage_(get)( \
val = THStorage_(get)( \
prob_dist->storage, \
prob_dist->storageOffset+i*prob_dist->stride[0]+j*prob_dist->stride[1] \
);
THArgCheckWithCleanup((val >= 0),
THCleanup(THDoubleTensor_free(cum_dist); if (start_dim == 1) THTensor_(resize1d)(prob_dist, n_categories);),
2,
"invalid multinomial distribution (encountering probability entry < 0)");
sum += val;
THDoubleStorage_set(
cum_dist->storage, \
cum_dist->storageOffset+j*cum_dist->stride[0], \
Expand Down
20 changes: 13 additions & 7 deletions aten/src/THC/THCTensorRandom.cuh
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Expand Up @@ -46,7 +46,7 @@ multinomialAliasDrawKernel(int size, int64_t *output, int64_t *J, T *q, int64_t
T bern_uniform = bernoulli[idx];
int _mask = (int) THCNumerics<T>::lt(bern_uniform, q[rand_ind]);
output[idx] = J[rand_ind]*(1 -_mask) + (rand_ind+1L) * _mask;
}
}
}

template <typename T>
Expand Down Expand Up @@ -94,15 +94,19 @@ template <typename T>
__global__ void renormRowsL1(T* dist, long rows, long cols) {
extern __shared__ unsigned char my_smem[];
T *smem = reinterpret_cast<T *>(my_smem);

T zero = ScalarConvert<int, T>::to(0);
T val;
for (int64_t row = blockIdx.x; row < rows; row += gridDim.x) {
T sum = ScalarConvert<int, T>::to(0);
for (int64_t col = threadIdx.x; col < cols; col += blockDim.x) {
sum = THCNumerics<T>::add(sum, dist[row * cols + col]);
val = dist[row * cols + col];
assert(THCNumerics<T>::ge(val, zero));
sum = THCNumerics<T>::add(sum, val);
}

sum = reduceBlock(smem, blockDim.x, sum, ReduceAdd<T, T>(), ScalarConvert<int, T>::to(0));
sum = reduceBlock(smem, blockDim.x, sum, ReduceAdd<T, T>(), zero);
if (threadIdx.x == 0) {
assert(THCNumerics<T>::gt(sum, zero));

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smem[0] = sum;
}
__syncthreads();
Expand Down Expand Up @@ -169,10 +173,11 @@ sampleMultinomialOnce(int64_t* dest,
// Each block handles one distribution
// First pass, find the total sum of the distribution
AccT sum = accZero;
T val;
for (int cat = threadIdx.x; cat < categories; cat += blockDim.x) {
sum = THCNumerics<AccT>::add(
sum,
ScalarConvert<T, AccT>::to(dist[curDist * categories + cat]));
val = dist[curDist * categories + cat];
assert(THCNumerics<T>::ge(val, zero));
sum = THCNumerics<AccT>::add(sum, ScalarConvert<T, AccT>::to(val));
}

// threadIdx.x == 0 has the sum value from this
Expand All @@ -182,6 +187,7 @@ sampleMultinomialOnce(int64_t* dest,
if (threadIdx.x == 0) {
// Make sure the sum of our distribution didn't overflow
assert(!isinf(sum));
assert(THCNumerics<AccT>::gt(sum, accZero));

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asmem[0] = sum;
smem[0] = sampled[curDist];
Expand Down