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authorMitja Felicijan <mitja.felicijan@gmail.com>2026-02-12 20:57:17 +0100
committerMitja Felicijan <mitja.felicijan@gmail.com>2026-02-12 20:57:17 +0100
commitb333b06772c89d96aacb5490d6a219fba7c09cc6 (patch)
tree211df60083a5946baa2ed61d33d8121b7e251b06 /llama.cpp/ggml/src/ggml-vulkan/vulkan-shaders/soft_max.comp
downloadllmnpc-b333b06772c89d96aacb5490d6a219fba7c09cc6.tar.gz
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diff --git a/llama.cpp/ggml/src/ggml-vulkan/vulkan-shaders/soft_max.comp b/llama.cpp/ggml/src/ggml-vulkan/vulkan-shaders/soft_max.comp
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+#version 450
+
+#extension GL_EXT_control_flow_attributes : enable
+
+layout (push_constant) uniform parameter
+{
+ uint KX;
+ uint KY;
+ uint ne00;
+ uint ne01;
+ uint ne02;
+ uint ne12;
+ uint ne13;
+ uint nb11;
+ uint nb12;
+ uint nb13;
+ float scale;
+ float max_bias;
+ float m0;
+ float m1;
+ uint n_head_log2;
+ uint nrows_x;
+ uint has_sinks;
+} p;
+
+#include "types.glsl"
+
+layout(constant_id = 0) const uint BLOCK_SIZE = 32;
+layout(local_size_x_id = 0, local_size_y = 1, local_size_z = 1) in;
+
+layout (binding = 0) readonly buffer X {A_TYPE data_a[];};
+layout (binding = 1) readonly buffer Y {B_TYPE data_b[];};
+layout (binding = 2) readonly buffer Z {float data_c[];};
+layout (binding = 3) buffer D {D_TYPE data_d[];};
+
+shared FLOAT_TYPE vals[BLOCK_SIZE];
+
+// num_iters is the number of BLOCK_SIZE loop iterations we need to iterate
+// over all the columns. The main function tries to pass a constant here,
+// as if it were a template function, to allow unrolling.
+void soft_max(uint num_iters) {
+ const uint tid = gl_LocalInvocationID.x;
+ const uint rowx = gl_WorkGroupID.z * 262144 + gl_WorkGroupID.y * 512 + gl_WorkGroupID.x;
+
+ const uint32_t i03 = rowx / (p.ne01 * p.ne02);
+ const uint32_t i02 = (rowx - i03 * p.ne01 * p.ne02) / p.ne01;
+ const uint32_t i01 = rowx % p.ne01;
+
+ uint rowy_start = 0;
+ if (p.KY > 0) {
+ rowy_start = i01 * p.nb11 + (i02 % p.ne12) * p.nb12 + (i03 % p.ne13) * p.nb13;
+ }
+
+ if (rowx >= p.nrows_x) {
+ return;
+ }
+
+ float slope = 1.0f;
+
+ // ALiBi
+ if (p.max_bias > 0.0f) {
+ const uint h = (rowx / p.ne01) % p.ne02; // head index
+
+ const float base = h < p.n_head_log2 ? p.m0 : p.m1;
+ const uint exp = h < p.n_head_log2 ? h + 1 : 2*(h - p.n_head_log2) + 1;
+
+ slope = pow(base, exp);
+ }
+
+ // Find max
+ FLOAT_TYPE max_val = p.has_sinks == 0 ? uintBitsToFloat(0xFF800000) : data_c[i02];
+
+ // Cache values while we compute the max, so we don't need to read them
+ // again when we're ready to compute exp(x-max).
+ const uint DATA_CACHE_SIZE = 16;
+ FLOAT_TYPE data_cache[DATA_CACHE_SIZE];
+
+ [[unroll]] for (uint col0 = 0, idx = 0; idx < num_iters; col0 += BLOCK_SIZE, ++idx) {
+ const uint col = col0 + tid;
+
+ FLOAT_TYPE a = FLOAT_TYPE(0);
+ if (col < p.KX) {
+ a = data_a[rowx * p.KX + col];
+ }
+
+ FLOAT_TYPE b = FLOAT_TYPE(0);
+ if (p.KY > 0 && col < p.KX) {
+ b = data_b[rowy_start + col];
+ }
+
+ FLOAT_TYPE v = a * p.scale + slope * b;
+
+ if (col < p.KX) {
+ max_val = max(max_val, v);
+ }
+
+ if (idx < DATA_CACHE_SIZE) {
+ data_cache[idx] = v;
+ }
+ }
+
+ // reduce across the workgroup
+ vals[tid] = max_val;
+ barrier();
+ [[unroll]] for (uint s = BLOCK_SIZE / 2; s > 0; s >>= 1) {
+ if (tid < s) {
+ vals[tid] = max(vals[tid], vals[tid + s]);
+ }
+ barrier();
+ }
+
+ max_val = vals[0];
+ barrier();
+
+ FLOAT_TYPE sum = FLOAT_TYPE(0.0f);
+
+ // Compute sum{exp(x - max)}
+ [[unroll]] for (uint col0 = 0, idx = 0; idx < num_iters; col0 += BLOCK_SIZE, ++idx) {
+ const uint col = col0 + tid;
+
+ if (col >= p.KX) {
+ break;
+ }
+
+ // compute exp(a*scale+b*slope), add it to sum, and cache the new value
+ // in data_cache if possible.
+ const uint i = rowx * p.KX + col;
+ FLOAT_TYPE val;
+ if (idx < DATA_CACHE_SIZE) {
+ val = exp(data_cache[idx] - max_val);
+ } else {
+ val = exp(FLOAT_TYPE(data_a[i]) * p.scale + (p.KY > 0 ? slope * FLOAT_TYPE(data_b[rowy_start + col]) : FLOAT_TYPE(0.0f)) - max_val);
+ }
+ sum += val;
+ if (idx < DATA_CACHE_SIZE) {
+ data_cache[idx] = val;
+ } else {
+ data_d[i] = D_TYPE(val);
+ }
+ }
+
+ // reduce across the workgroup
+ vals[tid] = sum;
+ barrier();
+ [[unroll]] for (uint s = BLOCK_SIZE / 2; s > 0; s >>= 1) {
+ if (tid < s) {
+ vals[tid] += vals[tid + s];
+ }
+ barrier();
+ }
+ sum = vals[0];
+
+ if (p.has_sinks != 0) {
+ sum += FLOAT_TYPE(exp(FLOAT_TYPE(data_c[i02]) - max_val));
+ }
+
+ FLOAT_TYPE rcpdivisor = 1.0/sum;
+
+ [[unroll]] for (uint col0 = 0, idx = 0; idx < num_iters; col0 += BLOCK_SIZE, ++idx) {
+ const uint col = col0 + tid;
+
+ if (col >= p.KX) {
+ continue;
+ }
+
+ if (idx < DATA_CACHE_SIZE) {
+ data_d[rowx*p.KX + col] = D_TYPE(data_cache[idx] * rcpdivisor);
+ } else {
+ data_d[rowx*p.KX + col] *= D_TYPE(rcpdivisor);
+ }
+ }
+}
+
+void main() {
+ // instantiate the soft_max function for several different
+ // dimensions, to allow loop unrolling
+ uint num_blocks = (p.KX + BLOCK_SIZE - 1) / BLOCK_SIZE;
+ if (num_blocks > 32) {
+ soft_max(num_blocks);
+ } else if (num_blocks > 16) {
+ soft_max(32);
+ } else if (num_blocks > 8) {
+ soft_max(16);
+ } else if (num_blocks > 4) {
+ soft_max(8);
+ } else if (num_blocks == 4) {
+ soft_max(4);
+ } else if (num_blocks == 3) {
+ soft_max(3);
+ } else if (num_blocks == 2) {
+ soft_max(2);
+ } else if (num_blocks == 1) {
+ soft_max(1);
+ }
+}