vulkan: skip unneeded MoE work in mul_mm coopmat1 path (#25483)

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

@@ -313,6 +313,9 @@ void main() {
 
     // Workgroup has no work
     if (ic * BN >= _ne1) return;
+
+    uint required_work_items = (_ne1 - ic * BN) * BK / LOAD_VEC_B_EFF / LOAD_VEC_BATCH_B;
+    uint required_warp_c = (_ne1 - ic * BN + WN - 1) / WN;
 #endif
 
 #ifdef MUL_MAT_ID
@@ -363,6 +366,9 @@ void main() {
         [[unroll]] for (uint l = 0; l < BM; l += loadstride_a) {
             load_a_to_shmem(pos_a, loadr_a, loadc_a + l, ir * BM + loadc_a + l, block, end_k);
         }
+        #ifdef MUL_MAT_ID
+        if (gl_LocalInvocationID.x < required_work_items) {
+        #endif
         [[unroll]] for (uint l = 0; l < BN; l += loadstride_b) {
 #if !defined(MUL_MAT_ID)
             load_b_to_shmem(pos_b, loadr_b, loadc_b + l, ic * BN + loadc_b + l, block, end_k);
@@ -370,6 +376,9 @@ void main() {
             load_b_to_shmem(pos_b, loadr_b, loadc_b + l, ic, _ne1, block, end_k);
 #endif
         }
+        #ifdef MUL_MAT_ID
+        }
+        #endif
 
         barrier();
 
@@ -377,6 +386,9 @@ void main() {
         pos_b += BK / LOAD_VEC_B_EFF;
 
 #ifdef COOPMAT
+#ifdef MUL_MAT_ID
+        if (warp_c < required_warp_c) {
+#endif
         [[unroll]] for (uint i = 0; i < BK; i += TK) {
             [[unroll]] for (uint cm_row = 0; cm_row < cms_per_row; cm_row++) {
                 // Load from shared into cache
@@ -389,6 +401,9 @@ void main() {
                 }
             }
         }
+#ifdef MUL_MAT_ID
+        }
+#endif
 #else
         [[unroll]] for (uint i = 0; i < BK / BK_STEP; i++) {
             // Load from shared into cache