rename ggml_backend_load_cpu_variants to ggml_backend_load_all_variants [no ci]

This commit renames and modifies the function
ggml_backend_load_cpu_variants to ggml_backend_load_all_variants. This
function now returns void and accepts a backend name as an argument, and
the function tries to load all the variants for the specified backend.

Author: danbev

ggml/include/ggml-backend.h

@@ -243,8 +243,8 @@ extern "C" {
     // Load all known backends from dynamic libraries
     GGML_API void               ggml_backend_load_all(void);
     GGML_API void               ggml_backend_load_all_from_path(const char * dir_path);
-    // Load all CPU dynamic libraries and register them
-    GGML_API ggml_backend_reg_t * ggml_backend_load_cpu_variants(void);
+    // Load all variants for a backend and register them
+    GGML_API void               ggml_backend_load_all_variants(const char * name);
 
     //
     // Backend scheduler

ggml/src/ggml-backend-reg.cpp

@@ -601,9 +601,9 @@ void ggml_backend_load_all_from_path(const char * dir_path) {
 #endif
 }
 
-ggml_backend_reg_t * ggml_backend_load_cpu_variants(void) {
+void ggml_backend_load_all_variants(const char * name) {
     // enumerate all the files that match [lib]ggml-name-*.[so|dll] in the search paths
-    const fs::path name_path = fs::u8path("cpu");
+    const fs::path name_path = fs::u8path(name);
     const fs::path file_prefix = backend_filename_prefix().native() + name_path.native() + fs::u8path("-").native();
     const fs::path file_extension = backend_filename_extension();
 
@@ -615,9 +615,6 @@ ggml_backend_reg_t * ggml_backend_load_cpu_variants(void) {
     search_paths.push_back(get_executable_path());
     search_paths.push_back(fs::current_path());
 
-    ggml_backend_reg_t * backends = nullptr;
-    size_t count = 0;
-    size_t capacity = 0;
     for (const auto & search_path : search_paths) {
         if (!fs::exists(search_path)) {
             GGML_LOG_DEBUG("%s: search path %s does not exist\n", __func__, path_str(search_path).c_str());
@@ -631,25 +628,12 @@ ggml_backend_reg_t * ggml_backend_load_cpu_variants(void) {
                 if (filename.native().find(file_prefix.native()) == 0 && ext == file_extension) {
                     fs::path path = search_path / filename;
                     ggml_backend_reg_t backend = get_reg().load_backend(path, false);
-                    if (backend) {
-                        if (count >= capacity) {
-                            capacity = capacity == 0 ? 4 : capacity * 2;
-                            ggml_backend_reg_t * new_backends = (ggml_backend_reg_t *)realloc(backends, (capacity + 1) * sizeof(ggml_backend_reg_t));
-
-                            if (!new_backends) {
-                                free(backends);
-                                return nullptr;
-                            }
-                            backends = new_backends;
-                        }
-                        backends[count++] = backend;
+                    if (backend == nullptr) {
+                        GGML_LOG_ERROR("%s: failed to load backend variant %s\n", __func__, path_str(entry.path()).c_str());
                     }
+
                 }
             }
         }
     }
-    if (backends) {
-        backends[count] = nullptr;
-    }
-    return backends;
 }

tests/test-backend-ops.cpp

@@ -6923,8 +6923,7 @@ static void print_backend_features(ggml_backend_t backend) {
 static bool test_cpu_variant(const char * variant_name, const char * op_names_filter,
         const char * params_filter, printer * output_printer) {
     std::string backend_ref_name = "CPU-ref";
-    ggml_backend_reg_t * backend_regs = ggml_backend_load_cpu_variants();
-    free(backend_regs);
+    ggml_backend_load_all_variants("cpu");
 
     ggml_backend_t backend_ref = ggml_backend_init_by_name(backend_ref_name.c_str(), nullptr);
     if (backend_ref == nullptr) {
@@ -6978,18 +6977,16 @@ static bool test_cpu_variant(const char * variant_name, const char * op_names_fi
 
 static void list_cpu_variants() {
     std::unordered_map<std::string, std::string> variant_names;
-    ggml_backend_reg_t * backend_regs = ggml_backend_load_cpu_variants();
-    if (backend_regs) {
-        for (ggml_backend_reg_t * reg = backend_regs; *reg != nullptr; ++reg) {
-            for (size_t j = 0; j < ggml_backend_reg_dev_count(*reg); j++) {
-                ggml_backend_dev_t dev = ggml_backend_reg_dev_get(*reg, j);
-                const char * name = ggml_backend_dev_name(dev);
-                if (strcmp(name, "CPU-ref") != 0) {
-                    variant_names.emplace(name, ggml_backend_dev_description(dev));
-                }
+    ggml_backend_load_all_variants("cpu");
+
+    for (size_t i = 0; i < ggml_backend_dev_count(); ++i) {
+        ggml_backend_dev_t dev = ggml_backend_dev_get(i);
+        if (ggml_backend_dev_type(dev) == GGML_BACKEND_DEVICE_TYPE_CPU) {
+            const char * name = ggml_backend_dev_name(dev);
+            if (strcmp(name, "CPU-ref") != 0) {
+                variant_names.emplace(name, ggml_backend_dev_description(dev));
             }
         }
-        free(backend_regs);
     }
 
     if (variant_names.size() == 0) {