tests: Generate unique input values for count_equal (#15487)

This avoids backend-dependent behavior for argmax that leads to intermittent failures.

ggml/src/ggml-metal/ggml-metal.m

@@ -93,35 +93,37 @@ static id<MTLDevice> ggml_backend_metal_device_acq(struct ggml_backend_metal_dev
     if (ctx->mtl_device == nil) {
         ctx->mtl_device = MTLCreateSystemDefaultDevice();
 
-        ctx->has_simdgroup_reduction  = [ctx->mtl_device supportsFamily:MTLGPUFamilyApple7];
-        ctx->has_simdgroup_reduction |= [ctx->mtl_device supportsFamily:MTLGPUFamilyMetal3_GGML];
+        if (ctx->mtl_device) {
+            ctx->has_simdgroup_reduction  = [ctx->mtl_device supportsFamily:MTLGPUFamilyApple7];
+            ctx->has_simdgroup_reduction |= [ctx->mtl_device supportsFamily:MTLGPUFamilyMetal3_GGML];
 
-        ctx->has_simdgroup_mm = [ctx->mtl_device supportsFamily:MTLGPUFamilyApple7];
+            ctx->has_simdgroup_mm = [ctx->mtl_device supportsFamily:MTLGPUFamilyApple7];
 
 #if defined(GGML_METAL_HAS_RESIDENCY_SETS)
-        ctx->has_residency_sets = getenv("GGML_METAL_NO_RESIDENCY") == nil;
+            ctx->has_residency_sets = getenv("GGML_METAL_NO_RESIDENCY") == nil;
 #endif
 
-        ctx->has_bfloat  = [ctx->mtl_device supportsFamily:MTLGPUFamilyMetal3_GGML];
-        ctx->has_bfloat |= [ctx->mtl_device supportsFamily:MTLGPUFamilyApple6];
+            ctx->has_bfloat  = [ctx->mtl_device supportsFamily:MTLGPUFamilyMetal3_GGML];
+            ctx->has_bfloat |= [ctx->mtl_device supportsFamily:MTLGPUFamilyApple6];
 
 #if defined(GGML_METAL_USE_BF16)
-        ctx->use_bfloat = ctx->has_bfloat;
+            ctx->use_bfloat = ctx->has_bfloat;
 #else
-        ctx->use_bfloat = false;
+            ctx->use_bfloat = false;
 #endif
-        ctx->use_fusion = getenv("GGML_METAL_FUSION_DISABLE") == nil;
+            ctx->use_fusion = getenv("GGML_METAL_FUSION_DISABLE") == nil;
 
-        {
-            const char * val = getenv("GGML_METAL_FUSION_DEBUG");
-            ctx->debug_fusion = val ? atoi(val) : 0;
+            {
+                const char * val = getenv("GGML_METAL_FUSION_DEBUG");
+                ctx->debug_fusion = val ? atoi(val) : 0;
+            }
+
+            memset(ctx->fuse_cnt, 0, sizeof(ctx->fuse_cnt));
+
+            ctx->max_size = ctx->mtl_device.maxBufferLength;
+
+            strncpy(ctx->name, [[ctx->mtl_device name] UTF8String], sizeof(ctx->name) - 1);
         }
-
-        memset(ctx->fuse_cnt, 0, sizeof(ctx->fuse_cnt));
-
-        ctx->max_size = ctx->mtl_device.maxBufferLength;
-
-        strncpy(ctx->name, [[ctx->mtl_device name] UTF8String], sizeof(ctx->name) - 1);
     }
 
     ctx->mtl_device_ref_count++;

tests/test-backend-ops.cpp

@@ -2209,6 +2209,26 @@ struct test_count_equal : public test_case {
     double max_nmse_err() override {
         return 0.0;
     }
+
+    void initialize_tensors(ggml_context * ctx) override {
+        std::random_device rd;
+        std::default_random_engine rng(rd());
+        for (ggml_tensor * t = ggml_get_first_tensor(ctx); t != NULL; t = ggml_get_next_tensor(ctx, t)) {
+            if (t->type == GGML_TYPE_F32) {
+                // initialize with unique values to avoid ties
+                for (int64_t r = 0; r < ggml_nrows(t); r++) {
+                    std::vector<float> data(t->ne[0]);
+                    for (int i = 0; i < t->ne[0]; i++) {
+                        data[i] = i;
+                    }
+                    std::shuffle(data.begin(), data.end(), rng);
+                    ggml_backend_tensor_set(t, data.data(), r * t->nb[1], t->ne[0] * sizeof(float));
+                }
+            } else {
+                init_tensor_uniform(t);
+            }
+        }
+    }
 };
 
 // GGML_OP_REPEAT