[NFC][SYCL] Clarify intent of device_image_impl::get_kernel_ids_ptr

Author: aelovikov-intel

sycl/source/detail/device_image_impl.hpp

@@ -417,6 +417,12 @@ class device_image_impl
   const std::vector<kernel_id> &get_kernel_ids() const noexcept {
     return *MKernelIDs;
   }
+  // This should only be used when creating new device_image_impls that have the
+  // exact same set of kernels as the source one. In all other scenarios the
+  // getter above is the one needed:
+  std::shared_ptr<std::vector<kernel_id>> &get_kernel_ids_ptr() noexcept {
+    return MKernelIDs;
+  }
 
   bool has_specialization_constants() const noexcept {
     // Lock the mutex to prevent when one thread in the middle of writing a
@@ -563,10 +569,6 @@ class device_image_impl
 
   const context &get_context() const noexcept { return MContext; }
 
-  std::shared_ptr<std::vector<kernel_id>> &get_kernel_ids_ptr() noexcept {
-    return MKernelIDs;
-  }
-
   std::vector<unsigned char> &get_spec_const_blob_ref() noexcept {
     return MSpecConstsBlob;
   }
@@ -1300,7 +1302,9 @@ class device_image_impl
   ur_program_handle_t MProgram = nullptr;
 
   // List of kernel ids available in this image, elements should be sorted
-  // according to LessByNameComp
+  // according to LessByNameComp. Shared between images for performance reasons
+  // (e.g. when we compile a single image it keeps the same kernels in it as the
+  // original source image).
   std::shared_ptr<std::vector<kernel_id>> MKernelIDs;
 
   // List of known kernel names.

sycl/source/detail/program_manager/program_manager.cpp

@@ -2905,10 +2905,8 @@ mergeImageData(const std::vector<device_image_plain> &Imgs,
   for (const device_image_plain &Img : Imgs) {
     device_image_impl &DeviceImageImpl = *getSyclObjImpl(Img);
     // Duplicates are not expected here, otherwise urProgramLink should fail
-    if (DeviceImageImpl.get_kernel_ids_ptr())
-      KernelIDs.insert(KernelIDs.end(),
-                       DeviceImageImpl.get_kernel_ids_ptr()->begin(),
-                       DeviceImageImpl.get_kernel_ids_ptr()->end());
+    KernelIDs.insert(KernelIDs.end(), DeviceImageImpl.get_kernel_ids().begin(),
+                     DeviceImageImpl.get_kernel_ids().end());
     // To be able to answer queries about specialziation constants, the new
     // device image should have the specialization constants from all the linked
     // images.

sycl/source/kernel_bundle.cpp

@@ -288,8 +288,8 @@ bool has_kernel_bundle_impl(const context &Ctx, const std::vector<device> &Devs,
       const std::shared_ptr<device_image_impl> &DeviceImageImpl =
           getSyclObjImpl(DeviceImage);
 
-      CombinedKernelIDs.insert(DeviceImageImpl->get_kernel_ids_ptr()->begin(),
-                               DeviceImageImpl->get_kernel_ids_ptr()->end());
+      CombinedKernelIDs.insert(DeviceImageImpl->get_kernel_ids().begin(),
+                               DeviceImageImpl->get_kernel_ids().end());
     }
   }