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vulkan: fix mul_mat_vec failure in backend tests (#12529)

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The OOB calculation could be wrong if the last iteration was during one of
the unrolled loops. Adjust the unrolling counts to avoid this. Add a couple
new backend tests that hit this failure on NVIDIA GPUs.
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Jeff Bolz 2025-03-24 01:56:17 -05:00 • committed by GitHub
parent 77f9c6bbe5
commit 9b169a4d4e
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ggml/src/ggml-vulkan/vulkan-shaders/mul_mat_vec.comp
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@ -105,6 +105,16 @@ void compute_outputs(const uint32_t first_row, const uint32_t num_rows) {
int unroll_count = 4;
uint unrolled_iters = num_iters & ~(unroll_count - 1);
#if K_PER_ITER == 2
// If the K dimension is odd, we need lastiter==true on the last iteration
// so OOB is computed correctly. Skip some unrolling to make that happen.
if ((p.ncols & 1) != 0 &&
unrolled_iters == num_iters &&
unrolled_iters > 0) {
unrolled_iters -= unroll_count;
}
#endif
uint i = 0;
while (i < unrolled_iters) {
// Manually partially unroll the loop
@ -113,8 +123,18 @@ void compute_outputs(const uint32_t first_row, const uint32_t num_rows) {
i++;
}
}
unroll_count = 2;
unrolled_iters = num_iters & ~(unroll_count - 1);
#if K_PER_ITER == 2
if ((p.ncols & 1) != 0 &&
unrolled_iters == num_iters &&
unrolled_iters > 0) {
unrolled_iters -= unroll_count;
}
#endif
while (i < unrolled_iters) {
// Manually partially unroll the loop
[[unroll]] for (uint k = 0; k < unroll_count; ++k) {