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vulkan: Fix validation failure in quantized flash attention #16292

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Sep 29, 2025
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vulkan: Fix validation failure in quantized flash attention #16292

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40 changes: 29 additions & 11 deletions ggml/src/ggml-vulkan/vulkan-shaders/flash_attn_base.comp
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Original file line number Diff line number Diff line change
Expand Up @@ -65,30 +65,48 @@ layout (binding = 5) writeonly buffer O {D_TYPE data_o[];};
#if defined(A_TYPE_PACKED16)
#define BINDING_IDX_K 0
#define BINDING_IDX_V 1
layout (binding = 1) readonly buffer KV_PACKED16 {A_TYPE_PACKED16 data_packed16[];} kv_packed[2];
layout (binding = 1) readonly buffer K_PACKED16 {A_TYPE_PACKED16 k_data_packed16[];} k_packed;
layout (binding = 2) readonly buffer V_PACKED16 {A_TYPE_PACKED16 v_data_packed16[];} v_packed;
#endif

#if defined(DATA_A_Q4_0)
#define BLOCK_BYTE_SIZE 18

vec4 dequantize4(uint ib, uint iqs, uint a_offset, uint binding_idx) {
uint vui_lo = uint(kv_packed[binding_idx].data_packed16[a_offset + ib].qs[(iqs & 0xF) / 2 + 0]);
uint vui_hi = uint(kv_packed[binding_idx].data_packed16[a_offset + ib].qs[(iqs & 0xF) / 2 + 1]);
uint shift = (iqs & 0x10) >> 2;
vui_lo >>= shift;
vui_hi >>= shift;

return float(kv_packed[binding_idx].data_packed16[a_offset + ib].d) * (vec4(vui_lo & 0xF, (vui_lo >> 8) & 0xF, vui_hi & 0xF, (vui_hi >> 8) & 0xF) - 8.0f);
if (binding_idx == BINDING_IDX_K) {
uint vui_lo = uint(k_packed.k_data_packed16[a_offset + ib].qs[(iqs & 0xF) / 2 + 0]);
uint vui_hi = uint(k_packed.k_data_packed16[a_offset + ib].qs[(iqs & 0xF) / 2 + 1]);
uint shift = (iqs & 0x10) >> 2;
vui_lo >>= shift;
vui_hi >>= shift;

return float(k_packed.k_data_packed16[a_offset + ib].d) * (vec4(vui_lo & 0xF, (vui_lo >> 8) & 0xF, vui_hi & 0xF, (vui_hi >> 8) & 0xF) - 8.0f);
} else {
uint vui_lo = uint(v_packed.v_data_packed16[a_offset + ib].qs[(iqs & 0xF) / 2 + 0]);
uint vui_hi = uint(v_packed.v_data_packed16[a_offset + ib].qs[(iqs & 0xF) / 2 + 1]);
uint shift = (iqs & 0x10) >> 2;
vui_lo >>= shift;
vui_hi >>= shift;

return float(v_packed.v_data_packed16[a_offset + ib].d) * (vec4(vui_lo & 0xF, (vui_lo >> 8) & 0xF, vui_hi & 0xF, (vui_hi >> 8) & 0xF) - 8.0f);
}
}
#endif

#if defined(DATA_A_Q8_0)
#define BLOCK_BYTE_SIZE 34
vec4 dequantize4(uint ib, uint iqs, uint a_offset, uint binding_idx) {
const i8vec2 v0 = unpack8(int32_t(kv_packed[binding_idx].data_packed16[a_offset + ib].qs[iqs / 2])).xy; // vec4 used due to #12147
const i8vec2 v1 = unpack8(int32_t(kv_packed[binding_idx].data_packed16[a_offset + ib].qs[iqs / 2 + 1])).xy;
if (binding_idx == BINDING_IDX_K) {
const i8vec2 v0 = unpack8(int32_t(k_packed.k_data_packed16[a_offset + ib].qs[iqs / 2])).xy; // vec4 used due to #12147
const i8vec2 v1 = unpack8(int32_t(k_packed.k_data_packed16[a_offset + ib].qs[iqs / 2 + 1])).xy;

return float(kv_packed[binding_idx].data_packed16[a_offset + ib].d) * vec4(v0.x, v0.y, v1.x, v1.y);
return float(k_packed.k_data_packed16[a_offset + ib].d) * vec4(v0.x, v0.y, v1.x, v1.y);
} else {
const i8vec2 v0 = unpack8(int32_t(v_packed.v_data_packed16[a_offset + ib].qs[iqs / 2])).xy; // vec4 used due to #12147
const i8vec2 v1 = unpack8(int32_t(v_packed.v_data_packed16[a_offset + ib].qs[iqs / 2 + 1])).xy;

return float(v_packed.v_data_packed16[a_offset + ib].d) * vec4(v0.x, v0.y, v1.x, v1.y);
}
}
#endif

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