Fix: Add BF16 conversion support for SYCL

Author: yingying0906

src/ggml-sycl/convert.cpp

@@ -2,6 +2,13 @@
 #include "dequantize.hpp"
 #include "presets.hpp"
 
+#if defined(__INTEL_LLVM_COMPILER)
+    #if __has_include(<sycl/ext/oneapi/bfloat16.hpp>)
+        #include <sycl/ext/oneapi/bfloat16.hpp>
+        #define GGML_SYCL_HAS_BF16
+    #endif
+#endif
+
 template <int qk, int qr, dequantize_kernel_t dequantize_kernel, typename dst_t>
 static void dequantize_block(const void * __restrict__ vx, dst_t * __restrict__ y, const int64_t k,
                              const sycl::nd_item<3> &item_ct1) {
@@ -566,6 +573,10 @@ to_fp16_sycl_t ggml_get_to_fp16_sycl(ggml_type type, ggml_tensor * dst) {
             return dequantize_row_iq4_nl_sycl;
         case GGML_TYPE_F32:
             return convert_unary_sycl<float>;
+#ifdef GGML_SYCL_HAS_BF16
+        case GGML_TYPE_BF16:
+            return convert_unary_sycl<sycl::ext::oneapi::bfloat16>;
+#endif
         default:
             return nullptr;
     }
@@ -627,6 +638,11 @@ to_fp32_sycl_t ggml_get_to_fp32_sycl(ggml_type type, ggml_tensor *dst) {
             return dequantize_row_iq4_nl_sycl;
         case GGML_TYPE_F16:
             return convert_unary_sycl<sycl::half>;
+#ifdef GGML_SYCL_HAS_BF16
+        case GGML_TYPE_BF16:
+            return convert_unary_sycl<sycl::ext::oneapi::bfloat16>;
+#endif
+            
         default:
             return nullptr;
     }
@@ -636,7 +652,11 @@ to_fp16_nc_sycl_t get_to_fp16_nc_sycl(ggml_type type) {
     switch (type) {
         case GGML_TYPE_F32:
             return convert_unary_nc_sycl<float>;
+#ifdef GGML_SYCL_HAS_BF16
+        case GGML_TYPE_BF16:
+            return convert_unary_nc_sycl<sycl::ext::oneapi::bfloat16>;
+#endif
         default:
             return nullptr;
     }
-}
+}