[SYCL][ABI-Break] Hide getPlugin symbol (#14616)

This function is not called anywhere from SYCL headers and therefore
there is no reason to have it exported.

It was made exported as part of ESIMD emulator plugin addition
(#2963), but that plugin was since
then deprecated and removed (#13295).

This is patch is essentially a by-product of #14145 and it is
done to simplify that change, i.e. PI plugins removal should not be
ABI-breaking by itself, we just need to cleanup some of our exported
symbols.

Author: AlexeySachkov

sycl/include/sycl/detail/pi.hpp

@@ -194,7 +194,7 @@ extern std::shared_ptr<plugin> GlobalPlugin;
 std::vector<PluginPtr> &initialize();
 
 // Get the plugin serving given backend.
-template <backend BE> __SYCL_EXPORT const PluginPtr &getPlugin();
+template <backend BE> const PluginPtr &getPlugin();
 
 // Utility Functions to get Function Name for a PI Api.
 template <PiApiKind PiApiOffset> struct PiFuncInfo {};

sycl/source/detail/pi.cpp

@@ -508,11 +508,10 @@ template <backend BE> const PluginPtr &getPlugin() {
                   "pi::getPlugin couldn't find plugin");
 }
 
-template __SYCL_EXPORT const PluginPtr &getPlugin<backend::opencl>();
-template __SYCL_EXPORT const PluginPtr &
-getPlugin<backend::ext_oneapi_level_zero>();
-template __SYCL_EXPORT const PluginPtr &getPlugin<backend::ext_oneapi_cuda>();
-template __SYCL_EXPORT const PluginPtr &getPlugin<backend::ext_oneapi_hip>();
+template const PluginPtr &getPlugin<backend::opencl>();
+template const PluginPtr &getPlugin<backend::ext_oneapi_level_zero>();
+template const PluginPtr &getPlugin<backend::ext_oneapi_cuda>();
+template const PluginPtr &getPlugin<backend::ext_oneapi_hip>();
 
 // Report error and no return (keeps compiler from printing warnings).
 // TODO: Probably change that to throw a catchable exception,

sycl/test/abi/sycl_symbols_linux.dump

@@ -3292,10 +3292,6 @@ _ZN4sycl3_V16detail28getValueFromDynamicParameterERNS0_3ext6oneapi12experimental
 _ZN4sycl3_V16detail2pi25contextSetExtendedDeleterERKNS0_7contextEPFvPvES6_
 _ZN4sycl3_V16detail2pi3dieEPKc
 _ZN4sycl3_V16detail2pi9assertionEbPKc
-_ZN4sycl3_V16detail2pi9getPluginILNS0_7backendE1EEERKSt10shared_ptrINS1_6pluginEEv
-_ZN4sycl3_V16detail2pi9getPluginILNS0_7backendE2EEERKSt10shared_ptrINS1_6pluginEEv
-_ZN4sycl3_V16detail2pi9getPluginILNS0_7backendE3EEERKSt10shared_ptrINS1_6pluginEEv
-_ZN4sycl3_V16detail2pi9getPluginILNS0_7backendE6EEERKSt10shared_ptrINS1_6pluginEEv
 _ZN4sycl3_V16detail30UnsampledImageAccessorBaseHost10getAccDataEv
 _ZN4sycl3_V16detail30UnsampledImageAccessorBaseHost6getPtrEv
 _ZN4sycl3_V16detail30UnsampledImageAccessorBaseHostC1ENS0_5rangeILi3EEENS0_6access4modeEPviiNS0_2idILi3EEENS0_18image_channel_typeENS0_19image_channel_orderERKNS0_13property_listE

sycl/test/abi/sycl_symbols_windows.dump

@@ -14,10 +14,6 @@
 ??$create_sub_devices@$0BAII@@device@_V1@sycl@@QEBA?AV?$vector@Vdevice@_V1@sycl@@V?$allocator@Vdevice@_V1@sycl@@@std@@@std@@W4partition_affinity_domain@info@12@@Z
 ??$create_sub_devices@$0BAIJ@@device@_V1@sycl@@QEBA?AV?$vector@Vdevice@_V1@sycl@@V?$allocator@Vdevice@_V1@sycl@@@std@@@std@@XZ
 ??$ext_oneapi_get_info@Umax_num_work_group_sync@kernel_queue_specific@info@experimental@oneapi@ext@_V1@sycl@@@kernel@_V1@sycl@@QEBA_KAEBVqueue@12@@Z
-??$getPlugin@$00@pi@detail@_V1@sycl@@YAAEBV?$shared_ptr@Vplugin@detail@_V1@sycl@@@std@@XZ
-??$getPlugin@$01@pi@detail@_V1@sycl@@YAAEBV?$shared_ptr@Vplugin@detail@_V1@sycl@@@std@@XZ
-??$getPlugin@$02@pi@detail@_V1@sycl@@YAAEBV?$shared_ptr@Vplugin@detail@_V1@sycl@@@std@@XZ
-??$getPlugin@$05@pi@detail@_V1@sycl@@YAAEBV?$shared_ptr@Vplugin@detail@_V1@sycl@@@std@@XZ
 ??$get_backend_info@Ubackend_version@device@info@_V1@sycl@@@context@_V1@sycl@@QEBA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ
 ??$get_backend_info@Ubackend_version@device@info@_V1@sycl@@@device@_V1@sycl@@QEBA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ
 ??$get_backend_info@Ubackend_version@device@info@_V1@sycl@@@event@_V1@sycl@@QEBA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ