From 464754143b18a476841406d17fae0368e88dd809 Mon Sep 17 00:00:00 2001
From: Ruben Ortlam <rortlam@redhat.com>
Date: Mon, 24 Aug 2026 13:48:58 +0200
Subject: [PATCH] skip computation for inactive tiles

---
 .../vulkan-shaders/mul_mmq_cm1.comp           | 20 +++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/ggml/src/ggml-vulkan/vulkan-shaders/mul_mmq_cm1.comp b/ggml/src/ggml-vulkan/vulkan-shaders/mul_mmq_cm1.comp
index db97784599..007ea3f51f 100644
--- a/ggml/src/ggml-vulkan/vulkan-shaders/mul_mmq_cm1.comp
+++ b/ggml/src/ggml-vulkan/vulkan-shaders/mul_mmq_cm1.comp
@@ -334,6 +334,12 @@ void main() {
         PREFETCH_BLOCK(start_k)
     }
 
+    const uint a_row0 = warp_r * WM;
+    const uint b_col0 = warp_c * WN;
+    const bool active_col_tile = ic * BN + b_col0 < p.N;
+
+    barrier();
+
     for (uint block = start_k; block < end_k; block += BK * BK_STEP) {
         // Store prefetched data to shmem
         STORE_BLOCK_TO_LDS(block)
@@ -349,6 +355,7 @@ void main() {
             PREFETCH_BLOCK(next_block)
         }
 
+        if (active_col_tile) {
         // Compute from shmem
         [[unroll]] for (uint ks = 0; ks < BK_STEP; ks++) {
             const uint K_SUB = BK / TK;
@@ -357,12 +364,12 @@ void main() {
 
             [[unroll]] for (uint r = 0; r < cms_per_row; r++) {
                 [[unroll]] for (uint h = 0; h < K_SUB; h++) {
-                    coopMatLoad(cache_a[r * K_SUB + h], buf_a_qs, (warp_r * WM + r * TM) * QPITCH + ks * (BK / 4) + h * (TK / 4), QPITCH, gl_CooperativeMatrixLayoutRowMajor);
+                    coopMatLoad(cache_a[r * K_SUB + h], buf_a_qs, (a_row0 + r * TM) * QPITCH + ks * (BK / 4) + h * (TK / 4), QPITCH, gl_CooperativeMatrixLayoutRowMajor);
                 }
             }
             [[unroll]] for (uint c = 0; c < cms_per_col; c++) {
                 [[unroll]] for (uint h = 0; h < K_SUB; h++) {
-                    coopMatLoad(cache_b[c * K_SUB + h], buf_b_qs, (warp_c * WN + c * TN) * QPITCH + ks * (BK / 4) + h * (TK / 4), QPITCH, gl_CooperativeMatrixLayoutColumnMajor);
+                    coopMatLoad(cache_b[c * K_SUB + h], buf_b_qs, (b_col0 + c * TN) * QPITCH + ks * (BK / 4) + h * (TK / 4), QPITCH, gl_CooperativeMatrixLayoutColumnMajor);
                 }
             }
 
@@ -371,7 +378,7 @@ void main() {
             float scale_b[cms_per_col * CM_ELEMS];
             [[unroll]] for (uint r = 0; r < cms_per_row; r++) {
                 [[unroll]] for (uint e = 0; e < CM_ELEMS; e++) {
-                    scale_a[r * CM_ELEMS + e] = buf_a_d[ks * BM + warp_r * WM + r * TM + elem_row[e]];
+                    scale_a[r * CM_ELEMS + e] = buf_a_d[ks * BM + a_row0 + r * TM + elem_row[e]];
                     if (USE_MAGIC_BIAS) {
                         nbias_a[r * CM_ELEMS + e] = -ACC_BIAS_F * scale_a[r * CM_ELEMS + e];
                     }
@@ -379,7 +386,7 @@ void main() {
             }
             [[unroll]] for (uint c = 0; c < cms_per_col; c++) {
                 [[unroll]] for (uint e = 0; e < CM_ELEMS; e++) {
-                    scale_b[c * CM_ELEMS + e] = buf_b_d[ks * BN + warp_c * WN + c * TN + elem_col[e]];
+                    scale_b[c * CM_ELEMS + e] = buf_b_d[ks * BN + b_col0 + c * TN + elem_col[e]];
                 }
             }
 
@@ -417,6 +424,7 @@ void main() {
                 }
             }
         }
+        }
 
         barrier();
     }
@@ -426,8 +434,8 @@ void main() {
 #undef B_IB_CALC
 #undef PREFETCH_BLOCK
 
-    const uint dr = ir * BM + warp_r * WM;
-    const uint dc = ic * BN + warp_c * WN;
+    const uint dr = ir * BM + a_row0;
+    const uint dc = ic * BN + b_col0;
 
 #ifdef MUL_MAT_ID
     [[unroll]] for (uint r = 0; r < cms_per_row; r++) {