ci: add zdnn backend build but not test (#29541)

* ci: add zdnn backend build but not test

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

* ci: attempt to run a ubuntu 26.04 container

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

* ci: set shell to bash

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

* ci: clean up comments

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

* ggml-zdnn: fix compiler errors

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

* vendor: attempt to ignore warnings from vendored files

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

---------

Signed-off-by: Aaron Teo <aaron.teo1@ibm.com>

.github/workflows/build-ibm.yml

@@ -100,6 +100,46 @@ jobs:
           wget https://huggingface.co/ggml-org/models/resolve/main/tinyllamas/stories260K-be.gguf
           ./bin/llama-completion -m stories260K-be.gguf -p "One day, Lily met a Shoggoth" -n 500 -c 256
 
+  ubuntu-26-zdnn-s390x:
+    name: ubuntu-26-zdnn-s390x
+    runs-on: ubuntu-24.04-s390x
+    container: ubuntu:26.04  # required to get GCC 15.1 and binutils 2.44
+    defaults:
+      run:
+        shell: bash
+
+    steps:
+      - name: Build Dependencies
+        id: build_depends
+        run: |
+          apt-get update
+          apt-get install -y --no-install-recommends \
+            build-essential cmake git ca-certificates \
+            libssl-dev libzdnn-dev
+
+      - name: Clone
+        id: checkout
+        uses: actions/checkout@v6
+
+      - name: Toolchain workaround (GCC 15)
+        run: |
+          apt-get install -y gcc-15 g++-15
+          echo "CC=gcc-15" >> "$GITHUB_ENV"
+          echo "CXX=g++-15" >> "$GITHUB_ENV"
+
+      - name: Build with zDNN Backend
+        id: cmake_build
+        run: |
+          cmake -B build \
+            -DLLAMA_FATAL_WARNINGS=ON \
+            -DGGML_NATIVE=OFF \
+            -DGGML_VXE=ON \
+            -DGGML_ZDNN=ON \
+            -DGGML_RPC=ON \
+            -DCMAKE_C_FLAGS="-march=arch15" \
+            -DCMAKE_CXX_FLAGS="-march=arch15"
+          time cmake --build build --config Release -j $(nproc)
+
   ubuntu-24-ppc64le:
     runs-on: ubuntu-24.04-ppc64le
 

ggml/include/ggml-zdnn.h

@@ -10,6 +10,8 @@ extern "C" {
 // device buffer
 GGML_BACKEND_API ggml_backend_buffer_type_t ggml_backend_zdnn_buffer_type(void);
 
+GGML_BACKEND_API bool ggml_backend_is_zdnn(ggml_backend_t backend);
+
 GGML_BACKEND_API ggml_backend_reg_t ggml_backend_zdnn_reg(void);
 
 #ifdef __cplusplus

ggml/src/ggml-zdnn/ggml-zdnn.cpp

@@ -443,15 +443,13 @@ static ggml_backend_i ggml_backend_zdnn_i = {
 };
 
 static ggml_guid_t ggml_backend_zdnn_guid(void) {
-    static const char * guid_str = "IBM-ZDNN-ACCELER";
-    return reinterpret_cast<ggml_guid_t>((void *)guid_str);
+    static char guid_str[] = "IBM-ZDNN-ACCELER";
+    return reinterpret_cast<ggml_guid_t>(guid_str);
 }
 
 bool ggml_backend_is_zdnn(ggml_backend_t backend) {
     return backend != NULL &&
            ggml_guid_matches(backend->guid, ggml_backend_zdnn_guid());
-
-    GGML_UNUSED(backend);
 }
 
 //
@@ -488,7 +486,7 @@ static void ggml_backend_zdnn_device_get_props(ggml_backend_dev_t dev, ggml_back
     props->description = ggml_backend_zdnn_device_get_description(dev);
     props->type        = ggml_backend_zdnn_device_get_type(dev);
     ggml_backend_zdnn_device_get_memory(dev, &props->memory_free, &props->memory_total);
-    props->caps = (ggml_backend_dev_caps) {
+    props->caps = {
         /* .async                = */ false,
         /* .host_buffer          = */ false,
         /* .buffer_from_host_ptr = */ false,
@@ -505,7 +503,7 @@ static ggml_backend_t ggml_backend_zdnn_device_init(ggml_backend_dev_t dev, cons
     }
 
     ggml_backend_t backend = (ggml_backend *)malloc(sizeof(ggml_backend));
-    *backend = (ggml_backend) {
+    *backend = {
         /* .guid       = */ ggml_backend_zdnn_guid(),
         /* .iface      = */ ggml_backend_zdnn_i,
         /* .device     = */ dev,
@@ -624,13 +622,13 @@ ggml_backend_reg_t ggml_backend_zdnn_reg(void) {
     atexit(ggml_zdnn_cleanup);
 
     {
-        g_ggml_backend_zdnn_reg = (ggml_backend_reg) {
+        g_ggml_backend_zdnn_reg = {
             /* .api_version = */ GGML_ZDNN_VERSION,
             /* .iface       = */ ggml_backend_zdnn_reg_i,
             /* .context     = */ NULL
         };
 
-        g_ggml_backend_zdnn_device = (ggml_backend_device) {
+        g_ggml_backend_zdnn_device = {
             /* .iface       = */ ggml_backend_zdnn_device_i,
             /* .reg         = */ &g_ggml_backend_zdnn_reg,
             /* .context     = */ &g_ggml_ctx_dev_main

vendor/stb/CMakeLists.txt

@@ -4,3 +4,7 @@ add_library(stb INTERFACE)
 add_library(vendor::stb ALIAS stb)
 
 target_include_directories(stb INTERFACE ..)
+
+if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+    target_compile_options(stb INTERFACE -Wno-maybe-uninitialized)
+endif()