[SYCL] Improve get_kernel_bundle performance (#5496)

The patch improves performance of get_kernel_bundle version which
takes a list of kernel_id's.

There are three main improvements:

    1. For faster search of binary image for given kernel ids a special map
    is prebuilt during initial image registration.
    2. To avoid constructing a vector of kernel_id's for a device image each
    time a special map is prebuilt during initial image registration.
    3. The vector of kernel_id's for device images is now shared to avoid
    unnecessary copies.

Author: romanovvlad

sycl/source/backend.cpp

@@ -187,7 +187,7 @@ make_kernel_bundle(pi_native_handle NativeHandle, const context &TargetContext,
   // this by pre-building the device image and extracting kernel info. We can't
   // do the same to user images, since they may contain references to undefined
   // symbols (e.g. when kernel_bundle is supposed to be joined with another).
-  std::vector<kernel_id> KernelIDs{};
+  auto KernelIDs = std::make_shared<std::vector<kernel_id>>();
   auto DevImgImpl = std::make_shared<device_image_impl>(
       nullptr, TargetContext, Devices, State, KernelIDs, PiProgram);
   device_image_plain DevImg{DevImgImpl};

sycl/source/detail/device_image_impl.hpp

@@ -32,6 +32,12 @@ __SYCL_INLINE_NAMESPACE(cl) {
 namespace sycl {
 namespace detail {
 
+template <class T> struct LessByHash {
+  bool operator()(const T &LHS, const T &RHS) const {
+    return getSyclObjImpl(LHS) < getSyclObjImpl(RHS);
+  }
+};
+
 // The class is impl counterpart for sycl::device_image
 // It can represent a program in different states, kernel_id's it has and state
 // of specialization constants for it
@@ -51,7 +57,8 @@ class device_image_impl {
 
   device_image_impl(const RTDeviceBinaryImage *BinImage, context Context,
                     std::vector<device> Devices, bundle_state State,
-                    std::vector<kernel_id> KernelIDs, RT::PiProgram Program)
+                    std::shared_ptr<std::vector<kernel_id>> KernelIDs,
+                    RT::PiProgram Program)
       : MBinImage(BinImage), MContext(std::move(Context)),
         MDevices(std::move(Devices)), MState(State), MProgram(Program),
         MKernelIDs(std::move(KernelIDs)) {
@@ -60,17 +67,17 @@ class device_image_impl {
 
   device_image_impl(const RTDeviceBinaryImage *BinImage, context Context,
                     std::vector<device> Devices, bundle_state State,
-                    std::vector<kernel_id> KernelIDs, RT::PiProgram Program,
-                    const SpecConstMapT &SpecConstMap,
+                    std::shared_ptr<std::vector<kernel_id>> KernelIDs,
+                    RT::PiProgram Program, const SpecConstMapT &SpecConstMap,
                     const std::vector<unsigned char> &SpecConstsBlob)
       : MBinImage(BinImage), MContext(std::move(Context)),
         MDevices(std::move(Devices)), MState(State), MProgram(Program),
         MKernelIDs(std::move(KernelIDs)), MSpecConstsBlob(SpecConstsBlob),
         MSpecConstSymMap(SpecConstMap) {}
 
   bool has_kernel(const kernel_id &KernelIDCand) const noexcept {
-    return std::binary_search(MKernelIDs.begin(), MKernelIDs.end(),
-                              KernelIDCand, LessByNameComp{});
+    return std::binary_search(MKernelIDs->begin(), MKernelIDs->end(),
+                              KernelIDCand, LessByHash<kernel_id>{});
   }
 
   bool has_kernel(const kernel_id &KernelIDCand,
@@ -83,7 +90,7 @@ class device_image_impl {
   }
 
   const std::vector<kernel_id> &get_kernel_ids() const noexcept {
-    return MKernelIDs;
+    return *MKernelIDs;
   }
 
   bool has_specialization_constants() const noexcept {
@@ -176,7 +183,9 @@ class device_image_impl {
 
   const context &get_context() const noexcept { return MContext; }
 
-  std::vector<kernel_id> &get_kernel_ids_ref() noexcept { return MKernelIDs; }
+  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;
@@ -312,7 +321,7 @@ class device_image_impl {
   RT::PiProgram MProgram = nullptr;
   // List of kernel ids available in this image, elements should be sorted
   // according to LessByNameComp
-  std::vector<kernel_id> MKernelIDs;
+  std::shared_ptr<std::vector<kernel_id>> MKernelIDs;
 
   // A mutex for sycnhronizing access to spec constants blob. Mutable because
   // needs to be locked in the const method for getting spec constant value.

sycl/source/detail/kernel_bundle_impl.hpp

@@ -28,12 +28,6 @@ __SYCL_INLINE_NAMESPACE(cl) {
 namespace sycl {
 namespace detail {
 
-template <class T> struct LessByHash {
-  bool operator()(const T &LHS, const T &RHS) const {
-    return getSyclObjImpl(LHS) < getSyclObjImpl(RHS);
-  }
-};
-
 static bool checkAllDevicesAreInContext(const std::vector<device> &Devices,
                                         const context &Context) {
   const std::vector<device> &ContextDevices = Context.get_devices();