From 0a58b4b546e9951074732ccf73935577a5da3696 Mon Sep 17 00:00:00 2001
From: fairydreaming <166155368+fairydreaming@users.noreply.github.com>
Date: Sat, 4 Jul 2026 13:37:37 +0200
Subject: [PATCH] ggml : fix broken CPU concat implementation for quantized
 types (llama/25247)
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* ggml : fix broken CPU concat implementation for quantized types

* tests : concat tests for quantized types

---------

Co-authored-by: Stanisław Szymczyk <sszymczy@gmail.com>
---
 ggml/src/ggml-cpu/ops.cpp | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/ggml/src/ggml-cpu/ops.cpp b/ggml/src/ggml-cpu/ops.cpp
index 6724686b8..c555831ce 100644
--- a/ggml/src/ggml-cpu/ops.cpp
+++ b/ggml/src/ggml-cpu/ops.cpp
@@ -1913,7 +1913,11 @@ static void ggml_compute_forward_concat_any(
     GGML_ASSERT(dim >= 0 && dim < 4);
 
     int64_t o[4] = {0, 0, 0, 0};
-    o[dim] = src0->ne[dim];
+    if (dim == 0) {
+        o[dim] = src0->ne[dim]/ggml_blck_size(src0->type);
+    } else {
+        o[dim] = src0->ne[dim];
+    }
 
     const char * x;
 
@@ -1921,8 +1925,8 @@ static void ggml_compute_forward_concat_any(
     for (int i3 = 0; i3 < ne3; i3++) {
         for (int i2 = ith; i2 < ne2; i2 += nth) {
             for (int i1 = 0; i1 < ne1; i1++) {
-                for (int i0 = 0; i0 < ne0; i0++) {
-                    if (i0 < ne00 && i1 < ne01 && i2 < ne02 && i3 < ne03) {
+                for (int i0 = 0; i0 < ne0/ggml_blck_size(dst->type); i0++) {
+                    if (i0 < ne00/ggml_blck_size(src0->type) && i1 < ne01 && i2 < ne02 && i3 < ne03) {
                         x = (const char *)src0->data + (i0       )*nb00 + (i1       )*nb01 + (i2       )*nb02 + (i3       )*nb03;
                     } else {
                         x = (const char *)src1->data + (i0 - o[0])*nb10 + (i1 - o[1])*nb11 + (i2 - o[2])*nb12 + (i3 - o[3])*nb13;
@@ -2071,6 +2075,14 @@ void ggml_compute_forward_concat(
     ggml_tensor * dst) {
 
     const ggml_tensor * src0 = dst->src[0];
+    const ggml_tensor * src1 = dst->src[1];
+
+    if (ggml_is_quantized(src0->type)) {
+        GGML_ASSERT(ggml_is_contiguous(src0));
+        GGML_ASSERT(ggml_is_contiguous(src1));
+        GGML_ASSERT(src0->ne[0] % ggml_blck_size(src0->type) == 0);
+        GGML_ASSERT(src1->ne[0] % ggml_blck_size(src1->type) == 0);
+    }
 
     switch (src0->type) {
         case GGML_TYPE_F16: