fix: avoid precision issues on vulkan backend (#980)

Author: leejet

common.hpp

@@ -242,14 +242,18 @@ class FeedForward : public GGMLBlock {
         }
 
         // net_1 is nn.Dropout(), skip for inference
-        float scale = 1.f;
+        bool force_prec_f32 = false;
+        float scale         = 1.f;
         if (precision_fix) {
             scale = 1.f / 128.f;
+#ifdef SD_USE_VULKAN
+            force_prec_f32 = true;
+#endif
         }
         // The purpose of the scale here is to prevent NaN issues in certain situations.
         // For example, when using Vulkan without enabling force_prec_f32,
         // or when using CUDA but the weights are k-quants.
-        blocks["net.2"] = std::shared_ptr<GGMLBlock>(new Linear(inner_dim, dim_out, true, false, false, scale));
+        blocks["net.2"] = std::shared_ptr<GGMLBlock>(new Linear(inner_dim, dim_out, true, false, force_prec_f32, scale));
     }
 
     struct ggml_tensor* forward(GGMLRunnerContext* ctx, struct ggml_tensor* x) {

qwen_image.hpp

@@ -94,10 +94,14 @@ namespace Qwen {
             blocks["norm_added_q"] = std::shared_ptr<GGMLBlock>(new RMSNorm(dim_head, eps));
             blocks["norm_added_k"] = std::shared_ptr<GGMLBlock>(new RMSNorm(dim_head, eps));
 
-            float scale = 1.f / 32.f;
+            float scale         = 1.f / 32.f;
+            bool force_prec_f32 = false;
+#ifdef SD_USE_VULKAN
+            force_prec_f32 = true;
+#endif
             // The purpose of the scale here is to prevent NaN issues in certain situations.
             // For example when using CUDA but the weights are k-quants (not all prompts).
-            blocks["to_out.0"] = std::shared_ptr<GGMLBlock>(new Linear(inner_dim, out_dim, out_bias, false, false, scale));
+            blocks["to_out.0"] = std::shared_ptr<GGMLBlock>(new Linear(inner_dim, out_dim, out_bias, false, force_prec_f32, scale));
             // to_out.1 is nn.Dropout
 
             blocks["to_add_out"] = std::shared_ptr<GGMLBlock>(new Linear(inner_dim, out_context_dim, out_bias, false, false, scale));