add [[unroll]] and remove unnecessary conditions

Author: zhiyuan1i

ggml/src/ggml-vulkan/vulkan-shaders/wkv6.comp

@@ -1,5 +1,7 @@
 #version 450
 
+#extension GL_EXT_control_flow_attributes : require
+
 #define BLOCK_SIZE 64
 layout(local_size_x = BLOCK_SIZE, local_size_y = 1, local_size_z = 1) in;
 
@@ -29,12 +31,12 @@ void main() {
     const uint state_size = C * head_size;
     const uint n_seq_tokens = T / B;
 
-    if (tid >= head_size || batch_id >= B || head_id >= H) {
+    if (batch_id >= B || head_id >= H) {
         return;
     }
 
     A_TYPE state[BLOCK_SIZE];
-    for (uint i = 0; i < head_size; i++) {
+    [[unroll]] for (uint i = 0; i < head_size; i++) {
         state[i] = state_in[batch_id * state_size + head_id * head_size * head_size
                           + i * head_size + tid];
     }
@@ -56,7 +58,7 @@ void main() {
         const A_TYPE v_val = v[t];
         A_TYPE y = 0.0;
 
-        for (uint j = 0; j < head_size; j += 4) {
+        [[unroll]] for (uint j = 0; j < head_size; j += 4) {
             vec4 k_vec = vec4(_k[j], _k[j+1], _k[j+2], _k[j+3]);
             vec4 r_vec = vec4(_r[j], _r[j+1], _r[j+2], _r[j+3]);
             vec4 tf_vec = vec4(_tf[j], _tf[j+1], _tf[j+2], _tf[j+3]);
@@ -78,7 +80,7 @@ void main() {
         dst[t] = y;
     }
 
-    for (uint i = 0; i < head_size; i++) {
+    [[unroll]] for (uint i = 0; i < head_size; i++) {
         dst[T * C + batch_id * state_size + head_id * head_size * head_size
             + i * head_size + tid] = state[i];
     }