[OpenMP] Take elf_common.c as a interface library

[tianshilei1992]

Summary

For now elf_common.c is taken as a common part included into
different plugin implementations directly via
#include "../../common/elf_common.c", which is not a best practice. Since it
is simple enough such that we don't need to create a real library for it, we just
take it as a interface library so that other targets can link it directly. Another
advantage of this method is, we don't need to add the folder into header search
path which can potentially pollute the search path.

VE and AMD platforms have not been tested because I don't have target machines.

[tianshilei1992]

Fixed wrong comments

[JonChesterfield]

Yep, that looks like it'll work. The included source is a good thing to get rid of. Did you consider a header only library instead? There isn't much code in elf_common and we already know the headers work in the various rtl.cpp

[tianshilei1992]

In D94443#2491165, @JonChesterfield wrote:

Yep, that looks like it'll work. The included source is a good thing to get rid of. Did you consider a header only library instead? There isn't much code in elf_common and we already know the headers work in the various rtl.cpp

Actually an interface library is the way in CMake to implement a header only library. :-)

[JonChesterfield]

Ah, missed that. I thought you were building an archive.

This is better than adding a depends clause on the header to each plugin. Lends itself to adding more common code over time too. Very good, thanks!

[jdoerfert]

Thanks for this.

openmp/libomptarget/plugins/CMakeLists.txt

 ##===----------------------------------------------------------------------===##
-# 
+#
 # Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 # See https://llvm.org/LICENSE.txt for license information.
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-# 
+#
 ##===----------------------------------------------------------------------===##
 #
 # Build plugins for the user system if available.
 #
 ##===----------------------------------------------------------------------===##
 
+add_subdirectory(common)
+
 # void build_generic_elf64(string tmachine, string tmachine_name, string tmachine_libname, string elf_machine_id);
 # - build a plugin for an ELF based generic 64-bit target based on libffi.
 # - tmachine: name of the machine processor as used in the cmake build system.
 # - tmachine_name: name of the machine to be printed with the debug messages.
 # - tmachine_libname: machine name to be appended to the plugin library name.
 macro(build_generic_elf64 tmachine tmachine_name tmachine_libname tmachine_triple elf_machine_id)
 if(CMAKE_SYSTEM_PROCESSOR MATCHES "${tmachine}$")
   if(LIBOMPTARGET_DEP_LIBELF_FOUND)
     if(LIBOMPTARGET_DEP_LIBFFI_FOUND)
-    
       libomptarget_say("Building ${tmachine_name} offloading plugin.")
-    
       include_directories(${LIBOMPTARGET_DEP_LIBFFI_INCLUDE_DIR})
       include_directories(${LIBOMPTARGET_DEP_LIBELF_INCLUDE_DIR})
-      
       # Define macro to be used as prefix of the runtime messages for this target.
       add_definitions("-DTARGET_NAME=${tmachine_name}")
-      
       # Define macro with the ELF ID for this target.
       add_definitions("-DTARGET_ELF_ID=${elf_machine_id}")
-    
-      add_library("omptarget.rtl.${tmachine_libname}" SHARED 
+      add_library("omptarget.rtl.${tmachine_libname}" SHARED
         ${CMAKE_CURRENT_SOURCE_DIR}/../generic-elf-64bit/src/rtl.cpp)
-        
       # Install plugin under the lib destination folder.
-      install(TARGETS "omptarget.rtl.${tmachine_libname}" 
+      install(TARGETS "omptarget.rtl.${tmachine_libname}"
         LIBRARY DESTINATION "${OPENMP_INSTALL_LIBDIR}")
-        
       target_link_libraries(
         "omptarget.rtl.${tmachine_libname}"
-        ${LIBOMPTARGET_DEP_LIBFFI_LIBRARIES} 
+        elf_common
+        ${LIBOMPTARGET_DEP_LIBFFI_LIBRARIES}
         ${LIBOMPTARGET_DEP_LIBELF_LIBRARIES}
         dl
         "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/../exports")
-    
       list(APPEND LIBOMPTARGET_TESTED_PLUGINS
         "omptarget.rtl.${tmachine_libname}")
 
       # Report to the parent scope that we are building a plugin.
-      set(LIBOMPTARGET_SYSTEM_TARGETS 
+      set(LIBOMPTARGET_SYSTEM_TARGETS
         "${LIBOMPTARGET_SYSTEM_TARGETS} ${tmachine_triple}" PARENT_SCOPE)
       set(LIBOMPTARGET_TESTED_PLUGINS
         "${LIBOMPTARGET_TESTED_PLUGINS}" PARENT_SCOPE)
-      
     else(LIBOMPTARGET_DEP_LIBFFI_FOUND)
       libomptarget_say("Not building ${tmachine_name} offloading plugin: libffi dependency not found.")
     endif(LIBOMPTARGET_DEP_LIBFFI_FOUND)
   else(LIBOMPTARGET_DEP_LIBELF_FOUND)
     libomptarget_say("Not building ${tmachine_name} offloading plugin: libelf dependency not found.")
   endif(LIBOMPTARGET_DEP_LIBELF_FOUND)
 else()
   libomptarget_say("Not building ${tmachine_name} offloading plugin: machine not found in the system.")

openmp/libomptarget/plugins/amdgpu/CMakeLists.txt

 # Install plugin under the lib destination folder.
 # When we build for debug, OPENMP_LIBDIR_SUFFIX get set to -debug
 install(TARGETS omptarget.rtl.amdgpu LIBRARY DESTINATION "lib${OPENMP_LIBDIR_SUFFIX}")
 
 set_property(TARGET omptarget.rtl.amdgpu PROPERTY INSTALL_RPATH "$ORIGIN")
 target_link_libraries(
   omptarget.rtl.amdgpu
   PRIVATE
+  elf_common
   hsa-runtime64::hsa-runtime64
   pthread dl elf
   "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/../exports"
   "-Wl,-z,defs"
   )
 
 # Report to the parent scope that we are building a plugin for amdgpu
 set(LIBOMPTARGET_SYSTEM_TARGETS "${LIBOMPTARGET_SYSTEM_TARGETS} amdgcn-amd-amdhsa" PARENT_SCOPE)
 

openmp/libomptarget/plugins/amdgpu/src/rtl.cpp

if (status != ATMI_STATUS_SUCCESS) {                                         \
      */                                                                        \
     DP(#msg " succeeded\n");                                                   \
   }
 #else
 #define check(msg, status)                                                     \
   {}
 #endif
 
-#include "../../common/elf_common.c"
+#include "elf_common.h"
 
 /// Keep entries table per device
 struct FuncOrGblEntryTy {
   __tgt_target_table Table;
   std::vector<__tgt_offload_entry> Entries;
 };
 
 enum ExecutionModeType {

openmp/libomptarget/plugins/common/CMakeLists.txt

+##===----------------------------------------------------------------------===##
+#
+# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+#
+##===----------------------------------------------------------------------===##
+#
+# Common parts which can be used by all plugins
+#
+##===----------------------------------------------------------------------===##
+
+add_subdirectory(elf_common)

openmp/libomptarget/plugins/common/elf_common/CMakeLists.txt

+##===----------------------------------------------------------------------===##
+#
+# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+#
+##===----------------------------------------------------------------------===##
+#
+# Common ELF functionality for target plugins
+#
+##===----------------------------------------------------------------------===##
+
+add_library(elf_common INTERFACE)
+
+target_include_directories(elf_common INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})

openmp/libomptarget/plugins/common/elf_common/elf_common.h

-//===-- elf_common.c - Common ELF functionality -------------------*- C -*-===//
+//===-- elf_common.h - Common ELF functionality -------------------*- C -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // Common ELF functionality for target plugins.
 // Must be included in the plugin source file AFTER omptarget.h has been
 // included and macro DP(...) has been defined.
 // .
 //
 //===----------------------------------------------------------------------===//
 
 #if !(defined(_OMPTARGET_DEBUG_H))
-#error Include elf_common.c in the plugin source AFTER Debug.h has\
+#error Include elf_common.h in the plugin source AFTER Debug.h has\
  been included.
 #endif
 
 #include <elf.h>
 #include <libelf.h>
 
 // Check whether an image is valid for execution on target_id
 static inline int32_t elf_check_machine(__tgt_device_image *image,
                                         uint16_t target_id) {
 
   // Is the library version incompatible with the header file?
   if (elf_version(EV_CURRENT) == EV_NONE) {
     DP("Incompatible ELF library!\n");
     return 0;
   }
 
   char *img_begin = (char *)image->ImageStart;

openmp/libomptarget/plugins/cuda/CMakeLists.txt

 include_directories(${LIBOMPTARGET_DEP_LIBELF_INCLUDE_DIRS})
 
 add_library(omptarget.rtl.cuda SHARED src/rtl.cpp)
 
 # Install plugin under the lib destination folder.
 install(TARGETS omptarget.rtl.cuda LIBRARY DESTINATION "${OPENMP_INSTALL_LIBDIR}")
 
 target_link_libraries(omptarget.rtl.cuda
+  elf_common
   ${LIBOMPTARGET_DEP_CUDA_DRIVER_LIBRARIES}
   ${LIBOMPTARGET_DEP_LIBELF_LIBRARIES}
   "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/../exports"
   "-Wl,-z,defs")
 
 # Report to the parent scope that we are building a plugin for CUDA.
 set(LIBOMPTARGET_SYSTEM_TARGETS "${LIBOMPTARGET_SYSTEM_TARGETS} nvptx64-nvidia-cuda" PARENT_SCOPE)

openmp/libomptarget/plugins/cuda/src/rtl.cpp

#define CUDA_ERR_STRING(err)                                                   \
   do {                                                                         \
     const char *errStr = nullptr;                                              \
     CUresult errStr_status = cuGetErrorString(err, &errStr);                   \
     if (errStr_status == CUDA_SUCCESS)                                         \
       REPORT("%s \n", errStr);                                                 \
   } while (false)
 #endif // OMPTARGET_DEBUG
 
-#include "../../common/elf_common.c"
+#include "elf_common.h"
 
 /// Keep entries table per device.
 struct FuncOrGblEntryTy {
   __tgt_target_table Table;
   std::vector<__tgt_offload_entry> Entries;
 };
 
 enum ExecutionModeType {

openmp/libomptarget/plugins/generic-elf-64bit/src/rtl.cpp

 #define TARGET_NAME Generic ELF - 64bit
 #endif
 #define DEBUG_PREFIX "TARGET " GETNAME(TARGET_NAME) " RTL"
 
 #ifndef TARGET_ELF_ID
 #define TARGET_ELF_ID 0
 #endif
 
-#include "../../common/elf_common.c"
+#include "elf_common.h"
 
 #define NUMBER_OF_DEVICES 4
 #define OFFLOADSECTIONNAME "omp_offloading_entries"
 
 /// Array of Dynamic libraries loaded for this target.
 struct DynLibTy {
   char *FileName;
   void *Handle;

openmp/libomptarget/plugins/ve/CMakeLists.txt

add_library("omptarget.rtl.${tmachine_libname}" SHARED
     ${CMAKE_CURRENT_SOURCE_DIR}/src/rtl.cpp)
 
   # Install plugin under the lib destination folder.
   install(TARGETS "omptarget.rtl.${tmachine_libname}"
     LIBRARY DESTINATION lib${OPENMP_LIBDIR_SUFFIX})
 
   target_link_libraries(
     "omptarget.rtl.${tmachine_libname}"
+    elf_common
     ${LIBOMPTARGET_DEP_LIBFFI_LIBRARIES}
     ${LIBOMPTARGET_DEP_LIBELF_LIBRARIES}
     ${additional_libs}
     "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/../exports -Wl,-z,defs")
 
   # Report to the parent scope that we are building a plugin.
   set(LIBOMPTARGET_SYSTEM_TARGETS
     "${LIBOMPTARGET_SYSTEM_TARGETS} ${tmachine_triple}" PARENT_SCOPE)
 else()
     libomptarget_say("Not building nec-aurora plugin: libveo or libveosinfo not found.")
 endif()

openmp/libomptarget/plugins/ve/src/rtl.cpp

 #endif
 
 #define DEBUG_PREFIX "Target " GETNAME(TARGET_NAME) " RTL"
 
 #ifndef TARGET_ELF_ID
 #define TARGET_ELF_ID 0
 #endif
 
-#include "../../common/elf_common.c"
+#include "elf_common.h"
 
 struct DynLibTy {
   char *FileName;
   uint64_t VeoLibHandle;
 };
 
 /// Keep entries table per device.
 struct FuncOrGblEntryTy {