[libomptarget] Read standard notes for ELF offload images

[vzakhari]

Summary

This patch is a piece of D99360.

The patch prints ELF notes in SHT/PT_NOTE sections/segments of the ELF offload images. The implementation is based on LLVM ELFObjectFile.

Debug output from the plugins would look like this:

TARGET Common ELF --> LLVMOMPOFFLOAD ELF note NT_LLVM_OPENMP_OFFLOAD_VERSION with value: '1.0'
TARGET Common ELF --> LLVMOMPOFFLOAD ELF note NT_LLVM_OPENMP_OFFLOAD_PRODUCER with value: 'LLVM'
TARGET Common ELF --> LLVMOMPOFFLOAD ELF note NT_LLVM_OPENMP_OFFLOAD_PRODUCER_VERSION with value: '13.0.0git 9f8975163c75b1f9f736f9a8e0a60e29ac062754'

[JonChesterfield]

That's a lot of code. Mostly straightforward, though the raw new/delete makes me slightly nervous. I think it's almost all here to abstract over libelf or llvm's elf library with a higher level interface. I haven't read through it carefully yet.

There is a profiling build that depends on llvm. Enabling that did break some builds. It might be worth reviewing whether to treat llvm binaries as a hard requirement for libomptarget.

Aside from that, if we want to continue on this path. I suspect we don't need a third interface. In particular, we can probably implement llvm's libelf interface in terms of elf.h or vice versa. I'd lean towards converting the plugins to use llvm libelf's interface and providing a fallback implementation of the (few) non-header pieces that are used by the plugins. That gives zero bug surface for builds using llvm's libelf and a clear path to dropping the gnu libelf dependency.

The other way round, implementing the subset of libelf that we use in terms of llvm (or from scratch, elf isn't very complicated), is simpler today as the plugins don't have to change, but kind of ties us into an abstraction layer that looks like debt in the medium term.

(tagging myself as reviewer because I'd like to drop the libelf dependency from the amdgpu plugin, and this is a path by which that could be done)

[vzakhari]

In D99553#2658055, @JonChesterfield wrote:

That's a lot of code. Mostly straightforward, though the raw new/delete makes me slightly nervous. I think it's almost all here to abstract over libelf or llvm's elf library with a higher level interface. I haven't read through it carefully yet.

This is correct. This is all here just to abstract ELF reading with a new interface.

There is a profiling build that depends on llvm. Enabling that did break some builds. It might be worth reviewing whether to treat llvm binaries as a hard requirement for libomptarget.

The LLVM ELF implementation is disabled by default for upstream, so it should not cause any issues with LLVM component libraries. I have tested the LLVM ELF implementation downstream, and I believe it is working now (I will upload my latest patch shortly).

Aside from that, if we want to continue on this path. I suspect we don't need a third interface. In particular, we can probably implement llvm's libelf interface in terms of elf.h or vice versa. I'd lean towards converting the plugins to use llvm libelf's interface and providing a fallback implementation of the (few) non-header pieces that are used by the plugins. That gives zero bug surface for builds using llvm's libelf and a clear path to dropping the gnu libelf dependency.

Implementing GNU libelf interface as-is via LLVM ELF is problematic because this will require const casting of constant references/pointers exposed by LLVM ELF. Another side effect of linking LLVM component libraries to the plugins is the binary size. The plugins grow in size quite significantly, and I do not know whether this is acceptable for everyone.

Can you please clarify which non-header pieces you are referring to?

The other way round, implementing the subset of libelf that we use in terms of llvm (or from scratch, elf isn't very complicated), is simpler today as the plugins don't have to change, but kind of ties us into an abstraction layer that looks like debt in the medium term.

(tagging myself as reviewer because I'd like to drop the libelf dependency from the amdgpu plugin, and this is a path by which that could be done)

FWIW, generic-elf-64bit code includes link.h (for link_map declaration), which, in turn, includes system elf.h. This will conflict with LLVM ELF, if we try to use it directly in generic-elf-64bit code.

I assume getting rid of GNU libelf dependency in all plugins will take some time. Moreover, not all plugin developers may be willing to switch to LLVM ELF implementaion. I wonder if we can start using the new interface, and then gradually switch to LLVM ELF and deprecate the new interface, if it is convenient for all.

[JonChesterfield]

Implementing GNU libelf interface as-is via LLVM ELF is problematic because this will require const casting of constant references/pointers exposed by LLVM ELF.

Ah, yes. GNU uses char* everywhere. We could implement that using the interfaces that take const char* by malloc&memcpy&free, but that is fairly horrible. We could implement the llvm elf interface in terms of gnu by casting away the const and hoping GNU doesn't actually mutate the arguments, but that seems hazardous too. Overall this seems to be digging in the wrong direction - we are taking on a lot of debt in order to preserve the ability to use libelf, which is only of use to toolchains that want to use llvm's libomptarget without compiling llvm.

Another side effect of linking LLVM component libraries to the plugins is the binary size. The plugins grow in size quite significantly, and I do not know whether this is acceptable for everyone.

This doesn't seem necessary. Either we dynamically link the LLVMObject and the footprint will hopefully be comparable to using libelf, or we statically link it and let the linker deadstrip.

openmp/libomptarget/plugins/common/elf_common/elf_common.cpp

55

Missed this at first glance. This patch is a functional change - it abstracts over the elf interface, and also does some new stuff with said interface. It would probably be easier/safer to review when split down that line.

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

21

This enum is presumably in llvm somewhere. We should include it from llvm (note that some other header-only files are already included from llvm, and the cmake ensures that it is available when building libomptarget). We may need to slightly refactor llvm first to make the numbers available without pulling it lots of other stuff.

[vzakhari]

Thank you for the comments, Jon!

Another side effect of linking LLVM component libraries to the plugins is the binary size. The plugins grow in size quite significantly, and I do not know whether this is acceptable for everyone.

This doesn't seem necessary. Either we dynamically link the LLVMObject and the footprint will hopefully be comparable to using libelf, or we statically link it and let the linker deadstrip.

I will rebuild it from scratch to see how big the difference is in the release build. I guess we do not care about the debug build (the code size hit is much bigger for the debug).

Just to reiterate, I believe we agreed that we should link LLVM ELF library statically, otherwise, it will have to become redistributable. This may be quite inconvenient for some users.

openmp/libomptarget/plugins/common/elf_common/elf_common.cpp

55

I can split it, but I wanted to have at least something functional in this patch.

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

21

Yes, these constants are defined in D99612.

elf_constants.h is included for both libelf and LLVM ELF implementations. If I include the LLVM ELF header file here it will conflict with libelf header files in libeld implementation. I can get rid of these definitions in two cases:

1. System elf.h gets these definitions, so that I can include two different headers defining these constants for two different implementations.
2. We get rid of libelf dependency altogether.

[JonChesterfield]

Right, we don't really have minutes for the weekly call.

I suggested we link the libraries dynamically when clang is linked dynamically and statically when clang is linked statically. Someone pointed out that libomptarget gets distributed with applications that haven't necessarily distributed clang, so unconditionally statically linking makes that use case much easier. That seems right to me, at least as the default cmake thing.

I've emailed openmp-dev. No objections yet. A suggestion for that is to dig out the profiler diff that wanted to unconditionally link an llvm library and reach out to the people who objected then, or to create a diff making the llvm library unconditionally linked in the context of the profiler and see if that attracts objections.

Once the gates are open (i.e. the profiler's required libs are in), depending on llvmobject et al are unlikely to cause further problems. One hopes. It's possible we'll want to link libomptarget itself against the libraries and have the plugins depend on libomptarget for elf munging, just so we don't have N+1 copies of llvm for N plugins. Unless we can statically link (some of) the plugins.

[vzakhari]

Hi Jon,
Regarding the LLVM component libraries linking into the libomptarget/plugins, I guess the bigger change is that OpenMP offload runtime will not build in out-of-tree mode. Should we actually start with disabling the out-of-tree builds, and see how people react to this?

[JonChesterfield]

In D99553#2677114, @vzakhari wrote:

Hi Jon,
Regarding the LLVM component libraries linking into the libomptarget/plugins, I guess the bigger change is that OpenMP offload runtime will not build in out-of-tree mode. Should we actually start with disabling the out-of-tree builds, and see how people react to this?

If I understand you correctly, we took that step some time ago. If you check the libomptarget cmake there's some logic that tries to find the rest of llvm and bails if it isn't available. That is currently used to allow including llvm headers - at least the amdgpu plugin does so to keep enums consistent between clang and the plugin. The most recent attempt to unconditionally link a llvm binary is discussed in the comments of D93055

[vzakhari]

In D99553#2677146, @JonChesterfield wrote:

In D99553#2677114, @vzakhari wrote:

Hi Jon,
Regarding the LLVM component libraries linking into the libomptarget/plugins, I guess the bigger change is that OpenMP offload runtime will not build in out-of-tree mode. Should we actually start with disabling the out-of-tree builds, and see how people react to this?

If I understand you correctly, we took that step some time ago. If you check the libomptarget cmake there's some logic that tries to find the rest of llvm and bails if it isn't available. That is currently used to allow including llvm headers - at least the amdgpu plugin does so to keep enums consistent between clang and the plugin. The most recent attempt to unconditionally link a llvm binary is discussed in the comments of D93055

Note that in D93055 there is still a path for OPENMP_STANDALONE_BUILD. I believe we have not yet abandoned the out-of-tree builds (https://openmp.llvm.org/README.txt). And it seems like a big change to me.

[JonChesterfield]

In D99553#2677180, @vzakhari wrote:

Note that in D93055 there is still a path for OPENMP_STANDALONE_BUILD. I believe we have not yet abandoned the out-of-tree builds (https://openmp.llvm.org/README.txt). And it seems like a big change to me.

That is true. I'm under the impression that a 'standalone build' means one without LLVM, in which case we would hit

# LLVM source tree is required at build time for libomptarget                                                                                                                                                      
if (NOT LIBOMPTARGET_LLVM_INCLUDE_DIRS)
  message(FATAL_ERROR "Missing definition for LIBOMPTARGET_LLVM_INCLUDE_DIRS")
endif()

in which case the branch in D93055 for standalone build would be dead, but 'standalone build' might not mean what I think it does.

The current status, as I understand it, is libomp can build without llvm available, but libomptarget requires a copy of llvm on disk and optionally a copy of the llvm support library.

[vzakhari]

The current status, as I understand it, is libomp can build without llvm available, but libomptarget requires a copy of llvm on disk and optionally a copy of the llvm support library.

You are right, libomptarget requires a copy of llvm on disk (for the header files). At the same time just a copy of the llvm support library is not enough to use it, e.g. for profiling or something else. You may see that D93055 uses add_llvm_library() that is simply not available in an out-of-tree build. In this change-set I am using llvm_update_compile_flags(), which also requires true in-tree build. Maybe we can make these macros available by using find_package(LLVM), but I am not sure about that.

So I believe getting rid of libelf dependency implies strong requirement for a true in-tree build, and this is a big change for downstream projects. I am not sure how I should approach this major shift.

[JonChesterfield]

Hitting consensus on unconditionally using the llvm libraries seems to be taking longer than I hoped. Perhaps this is therefore the way to go in the mean time? There's always the hope that we can delete this abstraction layer later.

edit: an alternative might be to move some of the llvm elf handling into header-only style

This patch still mixes the large but routine elf library shim with the note reading, those should be separate. Mostly for ease of review and testing - swapping out the elf library should leave everything still working, and if it doesn't, that'll be easier to track down in the smaller delta.

edit2: looked through the code again. Would it be a disaster to use the llvm native interface, with a fallback that goes through libelf that does a lot of largeish copies to handle the const char* vs char* distinction? We're not totally sure who needs the no-llvm-libraries build, so can perhaps assume they'll be OK with some performance overhead, and if they aren't, they'll speak up and we can reinstate something like this.

edit3: in all this I'm assuming llvm elf reports errors up the stack instead of aborting. That may not be a safe assumption. The runtime is set up for soft fail and recover, clang is not.

[vzakhari]

ping...
Can someone please review the updated (simplified) patch?

[JonChesterfield]

The commit message is out of date.

The implementation is very clear. Thank you for the ping, missed the patch update email.

Edit: appears I had some inline comments from a previous revision that I had not posted, please disregard them.

openmp/libomptarget/plugins/common/elf_common/elf_light.cpp

26

stuff like this is likely to be available in a freestanding llvm header already

43

I believe this to be correct for 64 bit elf. For example, from https://llvm.org/doxygen/BinaryFormat_2ELF_8h_source.html#l01659

using Elf64_Word = uint32_t;
// ...
// Node header for ELF64.
 struct Elf64_Nhdr {
   Elf64_Word n_namesz;
   Elf64_Word n_descsz;
   Elf64_Word n_type;
 };

I remember being surprised by Elf64_word being uint32_t last time I saw this.

[vzakhari]

In D99553#2935395, @JonChesterfield wrote:

The commit message is out of date.

The implementation is very clear. Thank you for the ping, missed the patch update email.

Edit: appears I had some inline comments from a previous revision that I had not posted, please disregard them.

Thank you for the review, Jon!
I would like to clarify whether I should wait for more comments at tomorrow meeting. If there are no objections, I will start merging the patches tomorrow.

[vzakhari]

In the latest update I added llvm-objcopy as a dependence for clang-offload-wrapper, because otherwise make check-libomptarget would fail.

[vzakhari]

Not working on the project any more.

openmp/libomptarget/plugins/amdgpu/CMakeLists.txt

 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
+  dl
+  ${LIBOMPTARGET_DEP_LIBELF_LIBRARIES}
+  ${OPENMP_PTHREAD_LIB}
   "-Wl,--version-script=${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/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)
+# Use libelf, is possible.
+# Otherwise, use LLVM ELF (unless OPENMP_STANDALONE_BUILD).
+option(LIBOMPTARGET_FORCE_LLVM_ELF
+  "Use LLVM ELFObjectFile implementation for elf_common.\
+  This requires in-tree build." OFF)
+add_library(elf_common OBJECT elf_common.cpp elf_light.cpp)
 
+if(LIBOMPTARGET_DEP_LIBELF_FOUND AND NOT LIBOMPTARGET_FORCE_LLVM_ELF)
+  target_compile_definitions(elf_common PRIVATE -DMAY_USE_LIBELF)
+  target_include_directories(elf_common PRIVATE
+    ${LIBOMPTARGET_DEP_LIBELF_INCLUDE_DIR})
+  target_link_libraries(elf_common INTERFACE
+    ${LIBOMPTARGET_DEP_LIBELF_LIBRARIES})
+elseif(NOT OPENMP_STANDALONE_BUILD)
+  llvm_update_compile_flags(elf_common)
+  set(LINK_LLVM_LIBS LLVMBinaryFormat LLVMObject LLVMSupport)
+  target_link_libraries(elf_common INTERFACE ${LINK_LLVM_LIBS})
+  add_dependencies(elf_common ${LINK_LLVM_LIBS})
+else(LIBOMPTARGET_DEP_LIBELF_FOUND AND NOT LIBOMPTARGET_FORCE_LLVM_ELF)
+  libomptarget_say("Not building elf_common offload plugin library: libelf dependency not found.")
+endif(LIBOMPTARGET_DEP_LIBELF_FOUND AND NOT LIBOMPTARGET_FORCE_LLVM_ELF)
+
+# The code uses Debug.h, which requires threads support.
+target_link_libraries(elf_common INTERFACE ${OPENMP_PTHREAD_LIB})
+
+# Expose elf_common.h directory to the users of this library.
 target_include_directories(elf_common INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})

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

-//===-- elf_common.h - 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.h in the plugin source AFTER Debug.h has\
- been included.
-#endif
+#ifndef LLVM_OPENMP_LIBOMPTARGET_PLUGINS_COMMON_ELF_COMMON_ELF_COMMON_H
+#define LLVM_OPENMP_LIBOMPTARGET_PLUGINS_COMMON_ELF_COMMON_ELF_COMMON_H
 
-#include <elf.h>
-#include <libelf.h>
+#include "elf_constants.h"
+#include "omptargetplugin.h"
+#include <cstdint>
+
+/// Return non-zero, if the given \p image is an ELF object, which
+/// e_machine matches \p target_id; return zero otherwise.
+EXTERN int32_t elf_check_machine(__tgt_device_image *image, uint16_t target_id);
+
+/// Return non-zero, if the given \p image is an ET_DYN ELF object;
+/// return zero otherwise.
+EXTERN int32_t elf_is_dynamic(__tgt_device_image *image);
 
-// 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;
-  char *img_end = (char *)image->ImageEnd;
-  size_t img_size = img_end - img_begin;
-
-  // Obtain elf handler
-  Elf *e = elf_memory(img_begin, img_size);
-  if (!e) {
-    DP("Unable to get ELF handle: %s!\n", elf_errmsg(-1));
-    return 0;
-  }
-
-  // Check if ELF is the right kind.
-  if (elf_kind(e) != ELF_K_ELF) {
-    DP("Unexpected ELF type!\n");
-    elf_end(e);
-    return 0;
-  }
-  Elf64_Ehdr *eh64 = elf64_getehdr(e);
-  Elf32_Ehdr *eh32 = elf32_getehdr(e);
-
-  if (!eh64 && !eh32) {
-    DP("Unable to get machine ID from ELF file!\n");
-    elf_end(e);
-    return 0;
-  }
-
-  uint16_t MachineID;
-  if (eh64 && !eh32)
-    MachineID = eh64->e_machine;
-  else if (eh32 && !eh64)
-    MachineID = eh32->e_machine;
-  else {
-    DP("Ambiguous ELF header!\n");
-    elf_end(e);
-    return 0;
-  }
-
-  elf_end(e);
-  return MachineID == target_id;
-}
-
-static inline int32_t elf_is_dynamic(__tgt_device_image *image) {
-
-  char *img_begin = (char *)image->ImageStart;
-  char *img_end = (char *)image->ImageEnd;
-  size_t img_size = img_end - img_begin;
-
-  // Obtain elf handler
-  Elf *e = elf_memory(img_begin, img_size);
-  if (!e) {
-    DP("Unable to get ELF handle: %s!\n", elf_errmsg(-1));
-    return 0;
-  }
-
-  Elf64_Ehdr *eh64 = elf64_getehdr(e);
-  Elf32_Ehdr *eh32 = elf32_getehdr(e);
-
-  if (!eh64 && !eh32) {
-    DP("Unable to get machine ID from ELF file!\n");
-    elf_end(e);
-    return 0;
-  }
-
-  uint16_t Type;
-  if (eh64 && !eh32)
-    Type = eh64->e_type;
-  else if (eh32 && !eh64)
-    Type = eh32->e_type;
-  else {
-    DP("Ambiguous ELF header!\n");
-    elf_end(e);
-    return 0;
-  }
-
-  elf_end(e);
-  DP("ELF Type: %d\n", Type);
-  return Type == ET_DYN;
-}
+#endif // LLVM_OPENMP_LIBOMPTARGET_PLUGINS_COMMON_ELF_COMMON_ELF_COMMON_H

openmp/libomptarget/plugins/common/elf_common/elf_common.cpp

+//===-- elf_common.cpp - Common ELF functionality -------------------------===//
+//
+// 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.
+//
+//===----------------------------------------------------------------------===//
+#include "elf_common.h"
+#include "Debug.h"
+#include "elf_light.h"
+
+#ifndef TARGET_NAME
+#define TARGET_NAME Common ELF
+#endif
+#define DEBUG_PREFIX "TARGET " GETNAME(TARGET_NAME)
+
+#ifdef ELFMAG
+// Subtle verification that libelf APIs are not used explicitly here.
+// Code here must use libelf independent APIs from elf_light.h.
+#error "LIBELF.H cannot be used explicitly here."
+#endif // ELFMAG
+
+EXTERN int32_t elf_check_machine(__tgt_device_image *image,
+                                 uint16_t target_id) {
+  char *img_begin = reinterpret_cast<char *>(image->ImageStart);
+  char *img_end = reinterpret_cast<char *>(image->ImageEnd);
+  size_t img_size = img_end - img_begin;
+  ElfL E(img_begin, img_size);
+  if (!E.isValidElf()) {
+    DP("Unable to get ELF handle: %s!\n", E.getErrmsg(-1));
+    return 0;
+  }
+
+  if (getDebugLevel() > 0) {
+    auto PrintOutNote = [](const ElfLNote &Note) {
+      if (Note.getNameSize() == 0)
+        return;
+
+      // Note that the NameStr below does not include the null
+      // terminator.
+      std::string NameStr(Note.getName(), Note.getNameSize());
+      if (NameStr != "LLVMOMPOFFLOAD")
+        return;
+
+      uint64_t Type = Note.getType();
+      switch (Type) {
+      default:
+        DP("LLVMOMPOFFLOAD ELF note with unknown type %" PRIu64 ".\n", Type);
+        break;
+      case NT_LLVM_OPENMP_OFFLOAD_VERSION:
+      case NT_LLVM_OPENMP_OFFLOAD_PRODUCER:
+      case NT_LLVM_OPENMP_OFFLOAD_PRODUCER_VERSION: {
+        std::string DescStr(reinterpret_cast<const char *>(Note.getDesc()),
+                            Note.getDescSize());
+        DP("LLVMOMPOFFLOAD ELF note %s with value: '%s'\n",
+           OMPNoteTypeNames[Type], DescStr.c_str());
+        break;
+      }
+      }
+    };
+
+    for (auto I = E.section_notes_begin(), IE = E.section_notes_end(); I != IE;
+         ++I)
+      PrintOutNote(*I);
+
+    for (auto I = E.segment_notes_begin(), IE = E.segment_notes_end(); I != IE;
+         ++I)
+      PrintOutNote(*I);
+  }
+  uint16_t MachineID = E.getEMachine();
+  return MachineID == target_id;
+}
+
+EXTERN int32_t elf_is_dynamic(__tgt_device_image *image) {
+  char *img_begin = reinterpret_cast<char *>(image->ImageStart);
+  char *img_end = reinterpret_cast<char *>(image->ImageEnd);
+  size_t img_size = img_end - img_begin;
+  ElfL E(img_begin, img_size);
+  if (!E.isValidElf()) {
+    DP("Unable to get ELF handle: %s!\n", E.getErrmsg(-1));
+    return 0;
+  }
+
+  uint16_t Type = E.getEType();
+  DP("ELF Type: %" PRIu16 "\n", Type);
+  return ElfL::isDynType(Type);
+}

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

+//===-- elf_constants.h - ELF constants -------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Here we duplicate some ELF constants that may not be yet available
+// in elf.h or llvm/BinaryFormat/ELF.h (e.g. in an out-of-tree build).
+// Note that we use the same constant names as in llvm/BinaryFormat/ELF.h.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_OPENMP_LIBOMPTARGET_PLUGINS_COMMON_ELF_COMMON_ELF_CONSTANTS_H
+#define LLVM_OPENMP_LIBOMPTARGET_PLUGINS_COMMON_ELF_COMMON_ELF_CONSTANTS_H
+
+// ELF notes with "LLVMOMPOFFLOAD" name may be of either of these types.
+enum : unsigned {
+  NT_LLVM_OPENMP_OFFLOAD_VERSION = 1,
+  NT_LLVM_OPENMP_OFFLOAD_PRODUCER = 2,
+  NT_LLVM_OPENMP_OFFLOAD_PRODUCER_VERSION = 3,
+  NT_LLVM_OPENMP_OFFLOAD_LAST = NT_LLVM_OPENMP_OFFLOAD_PRODUCER_VERSION
+};
+
+constexpr const char *OMPNoteTypeNames[NT_LLVM_OPENMP_OFFLOAD_LAST + 1] = {
+    "NT_LLVM_OPENMP_OFFLOAD_UNKNOWN",
+    "NT_LLVM_OPENMP_OFFLOAD_VERSION",
+    "NT_LLVM_OPENMP_OFFLOAD_PRODUCER",
+    "NT_LLVM_OPENMP_OFFLOAD_PRODUCER_VERSION",
+};
+
+#endif // LLVM_OPENMP_LIBOMPTARGET_PLUGINS_COMMON_ELF_COMMON_ELF_CONSTANTS_H

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

+//===-- elf_light.h - Basic 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Light ELF implementation provides basic ELF reading functionality.
+// It may be used in systems without libelf support, if the corresponding
+// LLVM ELF implementation is available.
+// The interface declared here must be independent of libelf.h/elf.h.
+//
+// NOTE: we can try to rely on https://github.com/WolfgangSt/libelf
+//       on Windows, if this implementation gets more complex.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_OPENMP_LIBOMPTARGET_PLUGINS_COMMON_ELF_COMMON_ELF_LIGHT_H
+#define LLVM_OPENMP_LIBOMPTARGET_PLUGINS_COMMON_ELF_COMMON_ELF_LIGHT_H
+
+#include <cstddef>
+#include <cstdint>
+#include <iterator>
+
+class ElfL;
+class ElfLSegmentNoteIterator;
+class ElfLSectionNoteIterator;
+class ElfNote;
+
+// Class representing NOTEs from PT_NOTE segments and SHT_NOTE sections.
+class ElfLNote {
+  const void *Impl = nullptr;
+
+  friend class ElfLSegmentNoteIterator;
+  friend class ElfLSectionNoteIterator;
+
+  // Only ElfLSectionNoteIterator is allowed to create notes via its
+  // operator*().
+  explicit ElfLNote(const void *I);
+  ElfLNote &operator=(const ElfLNote &) = delete;
+
+public:
+  // FIXME: add move copy constructor and assignment operator.
+  ElfLNote(const ElfLNote &);
+  ~ElfLNote();
+  // Returns the note's name size not including the null terminator.
+  // Note that it may be illegal to access the getName() pointer
+  // beyond the returned size, i.e. the implementation may
+  // not guarantee that there is '\0' after getNameSize()
+  // characters of the name.
+  uint64_t getNameSize() const;
+  // Returns a pointer to the beginning of the note's name.
+  const char *getName() const;
+  // Returns the number of bytes in the descriptor.
+  uint64_t getDescSize() const;
+  // Returns a pointer to the beginning of the note's descriptor.
+  // It is illegal to access more that getDescSize() bytes
+  // via this pointer.
+  const uint8_t *getDesc() const;
+  uint64_t getType() const;
+};
+
+// Iterator over NOTEs in PT_NOTE segments.
+class ElfLSegmentNoteIterator
+    : std::iterator<std::forward_iterator_tag, ElfLNote> {
+
+  void *Impl = nullptr;
+
+  friend class ElfL;
+
+  // Only ElfL is allowed to create iterators to itself.
+  ElfLSegmentNoteIterator(const void *I, bool IsEnd = false);
+  ElfLSectionNoteIterator &operator=(const ElfLSegmentNoteIterator &) = delete;
+
+public:
+  // FIXME: add move copy constructor and assignment operator.
+  ElfLSegmentNoteIterator(const ElfLSegmentNoteIterator &Other);
+  ~ElfLSegmentNoteIterator();
+  ElfLSegmentNoteIterator &operator++();
+  bool operator==(const ElfLSegmentNoteIterator Other) const;
+  bool operator!=(const ElfLSegmentNoteIterator Other) const;
+  ElfLNote operator*() const;
+};
+
+// Iterator over NOTEs in SHT_NOTE sections.
+class ElfLSectionNoteIterator
+    : std::iterator<std::forward_iterator_tag, ElfLNote> {
+
+  void *Impl = nullptr;
+
+  friend class ElfL;
+
+  // Only ElfL is allowed to create iterators to itself.
+  ElfLSectionNoteIterator(const void *I, bool IsEnd = false);
+  ElfLSectionNoteIterator &operator=(const ElfLSectionNoteIterator &) = delete;
+
+public:
+  // FIXME: add move copy constructor and assignment operator.
+  ElfLSectionNoteIterator(const ElfLSectionNoteIterator &Other);
+  ~ElfLSectionNoteIterator();
+  ElfLSectionNoteIterator &operator++();
+  bool operator==(const ElfLSectionNoteIterator Other) const;
+  bool operator!=(const ElfLSectionNoteIterator Other) const;
+  ElfLNote operator*() const;
+};
+
+// Wrapper around the given ELF image.
+class ElfL {
+  // Opaque pointer to the actual implementation.
+  void *Impl = nullptr;
+
+  // FIXME: implement if needed.
+  ElfL(const ElfL &) = delete;
+  ElfL &operator=(const ElfL &) = delete;
+
+public:
+  ElfL(char *Begin, size_t Size);
+  ~ElfL();
+  bool isValidElf() const;
+  const char *getErrmsg(int N) const;
+  uint16_t getEMachine() const;
+  uint16_t getEType() const;
+
+  static bool isDynType(uint16_t Ty);
+
+  ElfLSectionNoteIterator section_notes_begin() const;
+  ElfLSectionNoteIterator section_notes_end() const;
+  ElfLSegmentNoteIterator segment_notes_begin() const;
+  ElfLSegmentNoteIterator segment_notes_end() const;
+};
+
+#endif // LLVM_OPENMP_LIBOMPTARGET_PLUGINS_COMMON_ELF_COMMON_ELF_LIGHT_H

openmp/libomptarget/plugins/common/elf_common/elf_light.cpp

+//===-- elf_light.cpp - Basic 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "elf_light.h"
+#include "Debug.h"
+#include <assert.h>
+
+#ifndef TARGET_NAME
+#define TARGET_NAME ELF light
+#endif
+#define DEBUG_PREFIX "TARGET " GETNAME(TARGET_NAME)
+
+#if MAY_USE_LIBELF
+
+// Implementation based on libelf.
+#include <gelf.h>
+#include <libelf.h>
+
+// Helper methods to align addresses.
+template <typename T> inline T alignDown(T value, size_t alignment) {
+  return (T)(value & ~(alignment - 1));
+}
+
+template <typename T> inline T *alignDown(T *value, size_t alignment) {
+  return reinterpret_cast<T *>(alignDown((intptr_t)value, alignment));
+}
+
+template <typename T> inline T alignUp(T value, size_t alignment) {
+  return alignDown((T)(value + alignment - 1), alignment);
+}
+
+template <typename T> inline T *alignUp(T *value, size_t alignment) {
+  return reinterpret_cast<T *>(
+      alignDown((intptr_t)(value + alignment - 1), alignment));
+}
+
+// FIXME: this is taken from openmp/libomptarget/plugins/amdgpu/impl/system.cpp,
+//        but it may be incorrect for 64-bit ELF. Elf64_Nhdr and Elf32_Nhdr
+//        have different representation. The alignment used for the name and
+//        the descriptor is still 4 bytes. At the same time, it seems to work
+//        for 64-bit ELFs produced by LLVM.
+struct Elf_Note {
+  uint32_t n_namesz; // Length of note's name.
+  uint32_t n_descsz; // Length of note's value.
+  uint32_t n_type;   // Type of note.
+  // then name
+  // then padding, optional
+  // then desc, at 4 byte alignment (not 8, despite being elf64)
+};
+
+static const uint32_t NoteAlignment = 4;
+
+// Implementation of the iterator for SHT_NOTE sections.
+// The iterator allows processing all NOTEs in all SHT_NOTE sections
+// in the ELF image provided during the iterator object construction.
+class ElfLSectionNoteIteratorImpl {
+  // A pointer to Elf object created by elf_memory() for
+  // the ELF image we are going to iterate.
+  Elf *EF;
+
+  // A pointer to the current SHT_NOTE section.
+  // In the initial state of the iterator object this will actually
+  // point to the very first section in the ELF image, but it will be
+  // adjusted right away either to point to the first SHT_NOTE section
+  // or set to nullptr (if there are no SHT_NOTE sections).
+  Elf_Scn *CurrentSection = nullptr;
+
+  // A pointer to the current NOTE inside a SHT_NOTE section
+  // pointed by CurrentSection. If it is nullptr, then this means
+  // that the iterator object is an end() iterator.
+  Elf_Note *NPtr = nullptr;
+
+  uint64_t getNotesBeginAddr(const GElf_Shdr &Shdr) const {
+    return reinterpret_cast<uint64_t>(elf_rawfile(EF, nullptr)) +
+           Shdr.sh_offset;
+  }
+
+  uint64_t getNotesEndAddr(const GElf_Shdr &Shdr) const {
+    return getNotesBeginAddr(Shdr) + Shdr.sh_size;
+  }
+
+  uint64_t getNoteSize(const Elf_Note &Note) const {
+    return sizeof(Note) + alignUp(Note.n_namesz, NoteAlignment) +
+           alignUp(Note.n_descsz, NoteAlignment);
+  }
+
+  // Given the current state of the iterator object, advances
+  // the iterator forward to point to the next NOTE in the next
+  // SHT_NOTE section.
+  // If there is no such a NOTE, then it sets the iterator
+  // object to the end() state.
+  //
+  // Note that this method does not change the iterator, if
+  // NPtr is pointing to a valid note within CurrentSection.
+  // The iterator advancement in this case is done via operator++.
+  void autoAdvance(bool IsFirst = false) {
+    // Cannot advance, if CurrentSection is NULL.
+    if (!CurrentSection)
+      return;
+
+    // NPtr points to a valid NOTE in CurrentSection, thus,
+    // no auto advancement.
+    if (NPtr)
+      return;
+
+    GElf_Shdr Shdr;
+    gelf_getshdr(CurrentSection, &Shdr);
+
+    // CurrentSection is a valid section, and NPtr is an end() iterator.
+    //
+    // If IsFirst is true, then we just in the initial state, and
+    // we need to set CurrentSection to the first SHT_NOTE section (if any),
+    // and, then, NPtr to the first note in this section.
+    //
+    // If IsFirst is false, then we've reached the end of the current
+    // SHT_NOTE section, and should find the next section with notes.
+    if (!IsFirst || gelf_getshdr(CurrentSection, &Shdr)->sh_type != SHT_NOTE)
+      CurrentSection = elf_nextscn(EF, CurrentSection);
+
+    while (CurrentSection &&
+           gelf_getshdr(CurrentSection, &Shdr)->sh_type != SHT_NOTE)
+      CurrentSection = elf_nextscn(EF, CurrentSection);
+
+    if (!CurrentSection) {
+      // No more sections.
+      // Note that NPtr is already nullptr indicating the end() iterator.
+      return;
+    }
+
+    gelf_getshdr(CurrentSection, &Shdr);
+    uint64_t NotesBegin = getNotesBeginAddr(Shdr);
+    uint64_t NotesEnd = getNotesEndAddr(Shdr);
+    if (NotesBegin >= NotesEnd) {
+      // Something went wrong. Assume that we've reached
+      // the end of all notes.
+      CurrentSection = nullptr;
+      NPtr = nullptr;
+      return;
+    }
+
+    NPtr = reinterpret_cast<Elf_Note *>(NotesBegin);
+    assert(NPtr && "Invalid SHT_NOTE section.");
+  }
+
+  bool operator!=(const ElfLSectionNoteIteratorImpl Other) const {
+    return !(*this == Other);
+  }
+
+public:
+  ElfLSectionNoteIteratorImpl(Elf *RawElf, bool IsEnd = false) : EF(RawElf) {
+    assert(EF && "Trying to iterate invalid ELF.");
+
+    if (IsEnd) {
+      // NPtr equal to nullptr means end() iterator.
+      return;
+    }
+
+    // Set CurrentSection to the very first section,
+    // and let autoAdvance() find the first valid note (if any).
+    CurrentSection = elf_getscn(EF, 0);
+    autoAdvance(true);
+  }
+
+  bool operator==(const ElfLSectionNoteIteratorImpl Other) const {
+    // They should be pointing to the same NOTE to be equal.
+    return NPtr == Other.NPtr;
+  }
+
+  const Elf_Note *operator*() const {
+    assert(*this != ElfLSectionNoteIteratorImpl(EF, true) &&
+           "Dereferencing the end iterator.");
+    return NPtr;
+  }
+
+  // Advance to the next NOTE in the CurrentSection.
+  // If there is no next NOTE, then autoAdvance() to the next
+  // SHT_NOTE section and its first NOTE.
+  ElfLSectionNoteIteratorImpl &operator++() {
+    assert(*this != ElfLSectionNoteIteratorImpl(EF, true) &&
+           "Incrementing the end iterator.");
+
+    GElf_Shdr Shdr;
+    gelf_getshdr(CurrentSection, &Shdr);
+    uint64_t NotesBegin = getNotesBeginAddr(Shdr);
+    uint64_t NotesEnd = getNotesEndAddr(Shdr);
+    assert(reinterpret_cast<uint64_t>(NPtr) >= NotesBegin &&
+           reinterpret_cast<uint64_t>(NPtr) < NotesEnd &&
+           "Invalid pointer to a note computed somewhere else.");
+    (void)NotesBegin;
+
+    uint64_t NoteSize = getNoteSize(*NPtr);
+    NPtr =
+        reinterpret_cast<Elf_Note *>(reinterpret_cast<char *>(NPtr) + NoteSize);
+    if (reinterpret_cast<uint64_t>(NPtr) >= NotesEnd ||
+        reinterpret_cast<uint64_t>(NPtr) + sizeof(*NPtr) >= NotesEnd) {
+      // We've reached the end of the current NOTE section.
+      NPtr = nullptr;
+    }
+
+    // Auto advance to the next section, if needed.
+    autoAdvance();
+    return *this;
+  }
+};
+
+// Implementation of the iterator for PT_NOTE segments.
+// The iterator allows processing all NOTEs in all PT_NOTE segments
+// in the ELF image provided during the iterator object construction.
+class ElfLSegmentNoteIteratorImpl {
+  // A pointer to Elf object created by elf_memory() for
+  // the ELF image we are going to iterate.
+  Elf *EF;
+
+  // A pointer to the current PT_NOTE segment.
+  // In the initial state of the iterator object this will actually
+  // point to the very first segment in the ELF image, but it will be
+  // adjusted right away either to point to the first PT_NOTE segment
+  // or set to nullptr (if there are no PT_NOTE segments).
+  size_t NumberOfPhdrs = (std::numeric_limits<size_t>::max)();
+  size_t CurrentSegment = (std::numeric_limits<size_t>::max)();
+
+  // A pointer to the current NOTE inside a PT_NOTE segment
+  // pointed by CurrentSegment. If it is nullptr, then this means
+  // that the iterator object is an end() iterator.
+  Elf_Note *NPtr = nullptr;
+
+  uint64_t getNotesBeginAddr(const GElf_Phdr &Phdr) const {
+    return reinterpret_cast<uint64_t>(elf_rawfile(EF, nullptr)) + Phdr.p_offset;
+  }
+
+  uint64_t getNotesEndAddr(const GElf_Phdr &Phdr) const {
+    return getNotesBeginAddr(Phdr) + Phdr.p_filesz;
+  }
+
+  uint64_t getNoteSize(const Elf_Note &Note) const {
+    return sizeof(Note) + alignUp(Note.n_namesz, NoteAlignment) +
+           alignUp(Note.n_descsz, NoteAlignment);
+  }
+
+  // Given the current state of the iterator object, advances
+  // the iterator forward to point to the next NOTE in the next
+  // PT_NOTE segment.
+  // If there is no such a NOTE, then it sets the iterator
+  // object to the end() state.
+  //
+  // Note that this method does not change the iterator, if
+  // NPtr is pointing to a valid note within CurrentSegment.
+  // The iterator advancement in this case is done via operator++.
+  void autoAdvance(bool IsFirst = false) {
+    // Cannot advance, if CurrentSegment is invalid.
+    if (CurrentSegment >= NumberOfPhdrs)
+      return;
+
+    // NPtr points to a valid NOTE in CurrentSegment, thus,
+    // no auto advancement.
+    if (NPtr)
+      return;
+
+    GElf_Phdr Phdr;
+    gelf_getphdr(EF, CurrentSegment, &Phdr);
+
+    // CurrentSegment is a valid segment, and NPtr is an end() iterator.
+    //
+    // If IsFirst is true, then we just in the initial state, and
+    // we need to set CurrentSegment to the first PT_NOTE segment (if any),
+    // and, then, NPtr to the first note in this segment.
+    //
+    // If IsFirst is false, then we've reached the end of the current
+    // PT_NOTE segment, and should find the next segment with notes.
+    if (!IsFirst || Phdr.p_type != PT_NOTE)
+      ++CurrentSegment;
+
+    while (CurrentSegment < NumberOfPhdrs) {
+      if (gelf_getphdr(EF, CurrentSegment, &Phdr) != &Phdr)
+        continue;
+
+      if (Phdr.p_type == PT_NOTE)
+        break;
+
+      ++CurrentSegment;
+    }
+
+    if (CurrentSegment >= NumberOfPhdrs) {
+      // No more segments.
+      // Note that NPtr is already nullptr indicating the end() iterator.
+      return;
+    }
+
+    if (gelf_getphdr(EF, CurrentSegment, &Phdr) != &Phdr)
+      assert(false && "Invalid program header selected above.");
+
+    uint64_t NotesBegin = getNotesBeginAddr(Phdr);
+    uint64_t NotesEnd = getNotesEndAddr(Phdr);
+    if (NotesBegin >= NotesEnd) {
+      // Something went wrong. Assume that we've reached
+      // the end of all notes.
+      CurrentSegment = NumberOfPhdrs;
+      NPtr = nullptr;
+      return;
+    }
+
+    NPtr = reinterpret_cast<Elf_Note *>(NotesBegin);
+    assert(NPtr && "Invalid PT_NOTE segment.");
+  }
+
+  bool operator!=(const ElfLSegmentNoteIteratorImpl Other) const {
+    return !(*this == Other);
+  }
+
+public:
+  ElfLSegmentNoteIteratorImpl(Elf *RawElf, bool IsEnd = false) : EF(RawElf) {
+    assert(EF && "Trying to iterate invalid ELF.");
+
+    if (IsEnd) {
+      // NPtr equal to nullptr means end() iterator.
+      return;
+    }
+
+    // Set CurrentSegment to the very first segment,
+    // and let autoAdvance() find the first valid note (if any).
+    CurrentSegment = 0;
+
+    // Set NumberOfPhdrs to 0, if we cannot query it.
+    if (elf_getphdrnum(EF, &NumberOfPhdrs) != 0)
+      NumberOfPhdrs = 0;
+    autoAdvance(true);
+  }
+
+  bool operator==(const ElfLSegmentNoteIteratorImpl Other) const {
+    // They should be pointing to the same NOTE to be equal.
+    return NPtr == Other.NPtr;
+  }
+
+  const Elf_Note *operator*() const {
+    assert(*this != ElfLSegmentNoteIteratorImpl(EF, true) &&
+           "Dereferencing the end iterator.");
+    return NPtr;
+  }
+
+  // Advance to the next NOTE in the CurrentSegment.
+  // If there is no next NOTE, then autoAdvance() to the next
+  // PT_NOTE segment and its first NOTE.
+  ElfLSegmentNoteIteratorImpl &operator++() {
+    assert(*this != ElfLSegmentNoteIteratorImpl(EF, true) &&
+           "Incrementing the end iterator.");
+
+    GElf_Phdr Phdr;
+    gelf_getphdr(EF, CurrentSegment, &Phdr);
+    uint64_t NotesBegin = getNotesBeginAddr(Phdr);
+    uint64_t NotesEnd = getNotesEndAddr(Phdr);
+    assert(reinterpret_cast<uint64_t>(NPtr) >= NotesBegin &&
+           reinterpret_cast<uint64_t>(NPtr) < NotesEnd &&
+           "Invalid pointer to a note computed somewhere else.");
+    (void)NotesBegin;
+
+    uint64_t NoteSize = getNoteSize(*NPtr);
+    NPtr =
+        reinterpret_cast<Elf_Note *>(reinterpret_cast<char *>(NPtr) + NoteSize);
+    if (reinterpret_cast<uint64_t>(NPtr) >= NotesEnd ||
+        reinterpret_cast<uint64_t>(NPtr) + sizeof(*NPtr) >= NotesEnd) {
+      // We've reached the end of the current NOTE section.
+      NPtr = nullptr;
+    }
+
+    // Auto advance to the next section, if needed.
+    autoAdvance();
+    return *this;
+  }
+};
+
+// Actual implementation of ElfL via libelf.
+// It is constructed from an ELF image defined by its
+// starting pointer in memory and a length in bytes.
+class ElfLImpl {
+  // A pointer to Elf object created by elf_memory() for
+  // the ELF image.
+  Elf *EF = nullptr;
+
+  // Class of the ELF image.
+  unsigned ElfClass = ELFCLASSNONE;
+
+  // A pointer to the ELF image's header.
+  // Depending on the class it may be either 'Elf32_Ehdr *'
+  // or 'Elf64_Ehdr '.
+  const void *Header = nullptr;
+
+  // Let the owning object access this.
+  friend class ElfL;
+
+public:
+  ElfLImpl(Elf *RawElf, unsigned ElfClass, const void *Header)
+      : EF(RawElf), ElfClass(ElfClass), Header(Header) {}
+
+  // Allocates and constructs a new iterator for NOTEs in
+  // SHT_NOTE sections of the ELF image.
+  ElfLSectionNoteIteratorImpl *
+  createSectionNoteIteratorImpl(bool IsEnd) const {
+    return new ElfLSectionNoteIteratorImpl(EF, IsEnd);
+  }
+
+  // Allocates and constructs a new iterator for NOTEs in
+  // PT_NOTE segments of the ELF image.
+  ElfLSegmentNoteIteratorImpl *
+  createSegmentNoteIteratorImpl(bool IsEnd) const {
+    return new ElfLSegmentNoteIteratorImpl(EF, IsEnd);
+  }
+};
+
+ElfL::ElfL(char *Begin, size_t Size) {
+  Elf *ElfHandle = elf_memory(Begin, Size);
+  if (!ElfHandle) {
+    elf_end(ElfHandle);
+    return;
+  }
+
+  const Elf32_Ehdr *Header32 = elf32_getehdr(ElfHandle);
+  const Elf64_Ehdr *Header64 = elf64_getehdr(ElfHandle);
+
+  if (!Header32 == !Header64) {
+    // Ambiguous ELF header or unrecognized ELF image.
+    elf_end(ElfHandle);
+    return;
+  }
+
+  const void *Header = nullptr;
+  unsigned ElfClass = ELFCLASSNONE;
+
+  if (Header32) {
+    ElfClass = ELFCLASS32;
+    Header = reinterpret_cast<const void *>(Header32);
+  } else {
+    ElfClass = ELFCLASS64;
+    Header = reinterpret_cast<const void *>(Header64);
+  }
+
+  Impl = reinterpret_cast<void *>(new ElfLImpl(ElfHandle, ElfClass, Header));
+}
+
+ElfL::~ElfL() {
+  if (Impl) {
+    ElfLImpl *EImpl = reinterpret_cast<ElfLImpl *>(Impl);
+    elf_end(EImpl->EF);
+    delete EImpl;
+  }
+}
+
+bool ElfL::isValidElf() const {
+  ElfLImpl *EImpl = reinterpret_cast<ElfLImpl *>(Impl);
+  return Impl && EImpl->Header && EImpl->ElfClass != ELFCLASSNONE;
+}
+
+const char *ElfL::getErrmsg(int N) const { return elf_errmsg(-1); }
+
+uint16_t ElfL::getEMachine() const {
+  assert(isValidElf() && "Invalid ELF.");
+  ElfLImpl *EImpl = reinterpret_cast<ElfLImpl *>(Impl);
+  if (EImpl->ElfClass == ELFCLASS32)
+    return reinterpret_cast<const Elf32_Ehdr *>(EImpl->Header)->e_machine;
+  else if (EImpl->ElfClass == ELFCLASS64)
+    return reinterpret_cast<const Elf64_Ehdr *>(EImpl->Header)->e_machine;
+  else
+    assert(false && "Unsupported ELF class.");
+
+  return EM_NONE;
+}
+
+uint16_t ElfL::getEType() const {
+  assert(isValidElf() && "Invalid ELF.");
+  ElfLImpl *EImpl = reinterpret_cast<ElfLImpl *>(Impl);
+  if (EImpl->ElfClass == ELFCLASS32)
+    return reinterpret_cast<const Elf32_Ehdr *>(EImpl->Header)->e_type;
+  else if (EImpl->ElfClass == ELFCLASS64)
+    return reinterpret_cast<const Elf64_Ehdr *>(EImpl->Header)->e_type;
+  else
+    assert(false && "Unsupported ELF class.");
+
+  return ET_NONE;
+}
+
+bool ElfL::isDynType(uint16_t Ty) { return Ty == ET_DYN; }
+
+ElfLSectionNoteIterator ElfL::section_notes_begin() const {
+  return ElfLSectionNoteIterator(reinterpret_cast<const ElfLImpl *>(Impl));
+}
+
+ElfLSectionNoteIterator ElfL::section_notes_end() const {
+  return ElfLSectionNoteIterator(reinterpret_cast<const ElfLImpl *>(Impl),
+                                 true);
+}
+
+ElfLSectionNoteIterator::ElfLSectionNoteIterator(const void *I, bool IsEnd) {
+  const ElfLImpl *EImpl = reinterpret_cast<const ElfLImpl *>(I);
+  Impl = EImpl->createSectionNoteIteratorImpl(IsEnd);
+}
+
+ElfLSectionNoteIterator::ElfLSectionNoteIterator(
+    const ElfLSectionNoteIterator &Other) {
+  ElfLSectionNoteIteratorImpl *IImpl =
+      reinterpret_cast<ElfLSectionNoteIteratorImpl *>(Other.Impl);
+  Impl = new ElfLSectionNoteIteratorImpl(*IImpl);
+}
+
+ElfLSectionNoteIterator::~ElfLSectionNoteIterator() {
+  assert(Impl && "Invalid ElfLSectionNoteIterator object.");
+  ElfLSectionNoteIteratorImpl *IImpl =
+      reinterpret_cast<ElfLSectionNoteIteratorImpl *>(Impl);
+  delete IImpl;
+}
+
+bool ElfLSectionNoteIterator::operator==(
+    const ElfLSectionNoteIterator Other) const {
+  const ElfLSectionNoteIteratorImpl *Lhs =
+      reinterpret_cast<const ElfLSectionNoteIteratorImpl *>(Impl);
+  const ElfLSectionNoteIteratorImpl *Rhs =
+      reinterpret_cast<const ElfLSectionNoteIteratorImpl *>(Other.Impl);
+  return (*Lhs == *Rhs);
+}
+
+bool ElfLSectionNoteIterator::operator!=(
+    const ElfLSectionNoteIterator Other) const {
+  return !(*this == Other);
+}
+
+ElfLSectionNoteIterator &ElfLSectionNoteIterator::operator++() {
+  ElfLSectionNoteIteratorImpl *IImpl =
+      reinterpret_cast<ElfLSectionNoteIteratorImpl *>(Impl);
+  ++(*IImpl);
+  return *this;
+}
+
+ElfLNote ElfLSectionNoteIterator::operator*() const {
+  ElfLSectionNoteIteratorImpl *IImpl =
+      reinterpret_cast<ElfLSectionNoteIteratorImpl *>(Impl);
+  return ElfLNote(**IImpl);
+}
+
+ElfLSegmentNoteIterator ElfL::segment_notes_begin() const {
+  return ElfLSegmentNoteIterator(reinterpret_cast<const ElfLImpl *>(Impl));
+}
+
+ElfLSegmentNoteIterator ElfL::segment_notes_end() const {
+  return ElfLSegmentNoteIterator(reinterpret_cast<const ElfLImpl *>(Impl),
+                                 true);
+}
+
+ElfLSegmentNoteIterator::ElfLSegmentNoteIterator(const void *I, bool IsEnd) {
+  const ElfLImpl *EImpl = reinterpret_cast<const ElfLImpl *>(I);
+  Impl = EImpl->createSegmentNoteIteratorImpl(IsEnd);
+}
+
+ElfLSegmentNoteIterator::ElfLSegmentNoteIterator(
+    const ElfLSegmentNoteIterator &Other) {
+  ElfLSegmentNoteIteratorImpl *IImpl =
+      reinterpret_cast<ElfLSegmentNoteIteratorImpl *>(Other.Impl);
+  Impl = new ElfLSegmentNoteIteratorImpl(*IImpl);
+}
+
+ElfLSegmentNoteIterator::~ElfLSegmentNoteIterator() {
+  assert(Impl && "Invalid ElfLSegmentNoteIterator object.");
+  ElfLSegmentNoteIteratorImpl *IImpl =
+      reinterpret_cast<ElfLSegmentNoteIteratorImpl *>(Impl);
+  delete IImpl;
+}
+
+bool ElfLSegmentNoteIterator::operator==(
+    const ElfLSegmentNoteIterator Other) const {
+  const ElfLSegmentNoteIteratorImpl *Lhs =
+      reinterpret_cast<const ElfLSegmentNoteIteratorImpl *>(Impl);
+  const ElfLSegmentNoteIteratorImpl *Rhs =
+      reinterpret_cast<const ElfLSegmentNoteIteratorImpl *>(Other.Impl);
+  return (*Lhs == *Rhs);
+}
+
+bool ElfLSegmentNoteIterator::operator!=(
+    const ElfLSegmentNoteIterator Other) const {
+  return !(*this == Other);
+}
+
+ElfLSegmentNoteIterator &ElfLSegmentNoteIterator::operator++() {
+  ElfLSegmentNoteIteratorImpl *IImpl =
+      reinterpret_cast<ElfLSegmentNoteIteratorImpl *>(Impl);
+  ++(*IImpl);
+  return *this;
+}
+
+ElfLNote ElfLSegmentNoteIterator::operator*() const {
+  ElfLSegmentNoteIteratorImpl *IImpl =
+      reinterpret_cast<ElfLSegmentNoteIteratorImpl *>(Impl);
+  return ElfLNote(**IImpl);
+}
+
+ElfLNote::ElfLNote(const void *I) {
+  // ElfLNote::Impl is a pointer to Elf_Note in this implementation.
+  // A pointer to Elf_Note is returned by
+  // ElfLSectionNoteIteratorImpl::operator*().
+  Impl = I;
+}
+
+ElfLNote::ElfLNote(const ElfLNote &Other) { Impl = Other.Impl; }
+
+ElfLNote::~ElfLNote() {}
+
+uint64_t ElfLNote::getNameSize() const {
+  const Elf_Note *Note = reinterpret_cast<const Elf_Note *>(Impl);
+  if (Note->n_namesz == 0)
+    return 0;
+  // libelf returns name size that accounts for the null terminator.
+  // ELF light interface returns the size ignoring it.
+  return Note->n_namesz - 1;
+}
+
+const char *ElfLNote::getName() const {
+  const Elf_Note *Note = reinterpret_cast<const Elf_Note *>(Impl);
+  return reinterpret_cast<const char *>(Note) + sizeof(*Note);
+}
+
+uint64_t ElfLNote::getDescSize() const {
+  const Elf_Note *Note = reinterpret_cast<const Elf_Note *>(Impl);
+  return Note->n_descsz;
+}
+
+const uint8_t *ElfLNote::getDesc() const {
+  const Elf_Note *Note = reinterpret_cast<const Elf_Note *>(Impl);
+  return reinterpret_cast<const uint8_t *>(Note) + sizeof(*Note) +
+         alignUp(getNameSize(), NoteAlignment);
+}
+
+uint64_t ElfLNote::getType() const {
+  const Elf_Note *Note = reinterpret_cast<const Elf_Note *>(Impl);
+  return Note->n_type;
+}
+
+#else // !MAY_USE_LIBELF
+
+// Implementation based on LLVM ELF binary format.
+#include "llvm/Object/Binary.h"
+#include "llvm/Object/ELFObjectFile.h"
+#include "llvm/Object/ELFTypes.h"
+#include "llvm/Object/ObjectFile.h"
+#include "llvm/Support/MemoryBuffer.h"
+
+using namespace llvm;
+using namespace llvm::ELF;
+using namespace llvm::object;
+
+class ElfLNoteImplBase {
+public:
+  virtual ~ElfLNoteImplBase() = default;
+  virtual ElfLNoteImplBase *clone() const = 0;
+  virtual size_t getNameSize() const = 0;
+  virtual const char *getName() const = 0;
+  virtual size_t getDescSize() const = 0;
+  virtual const uint8_t *getDesc() const = 0;
+  virtual uint32_t getType() const = 0;
+};
+
+template <class ELFT> class ElfLNoteImpl : public ElfLNoteImplBase {
+  using Elf_Note = typename ELFT::Note;
+  const Elf_Note Note;
+
+public:
+  ElfLNoteImpl(const Elf_Note Note) : Note(Note) {}
+  ElfLNoteImpl(const ElfLNoteImpl &) = default;
+  ElfLNoteImplBase *clone() const override { return new ElfLNoteImpl(*this); }
+  ~ElfLNoteImpl() = default;
+  size_t getNameSize() const override { return Note.getName().size(); }
+  const char *getName() const override { return Note.getName().data(); }
+  size_t getDescSize() const override { return Note.getDesc().size(); }
+  const uint8_t *getDesc() const override { return Note.getDesc().data(); }
+  uint32_t getType() const override { return Note.getType(); }
+};
+
+class ElfLNoteIteratorImplBase {
+protected:
+  const endianness TargetEndianness;
+  const bool Is64Bits;
+  const bool IsSectionIterator;
+
+  ElfLNoteIteratorImplBase(endianness TargetEndianness, bool Is64Bits,
+                           bool IsSectionIterator)
+      : TargetEndianness(TargetEndianness), Is64Bits(Is64Bits),
+        IsSectionIterator(IsSectionIterator) {}
+
+public:
+  ElfLNoteIteratorImplBase(const ElfLNoteIteratorImplBase &) = default;
+  virtual ~ElfLNoteIteratorImplBase() = default;
+  virtual ElfLNoteIteratorImplBase *clone() const = 0;
+  virtual ElfLNoteIteratorImplBase &operator++() = 0;
+  virtual bool operator==(const ElfLNoteIteratorImplBase &) const = 0;
+  virtual ElfLNoteImplBase *operator*() const = 0;
+
+  endianness getEndianness() const { return TargetEndianness; }
+
+  bool is64Bits() const { return Is64Bits; }
+
+  bool isSectionIterator() const { return IsSectionIterator; }
+};
+
+template <class ELFT>
+class ElfLNoteIteratorImpl : public ElfLNoteIteratorImplBase {
+protected:
+  using NoteIterator = typename ELFT::NoteIterator;
+
+  const ELFFile<ELFT> &EF;
+  NoteIterator NotesIt;
+  Error &Err;
+
+  explicit ElfLNoteIteratorImpl(const ELFFile<ELFT> &EF, Error &Err,
+                                bool IsSectionIterator)
+      : ElfLNoteIteratorImplBase(ELFT::TargetEndianness, ELFT::Is64Bits,
+                                 IsSectionIterator),
+        EF(EF), NotesIt(EF.notes_end()), Err(Err) {}
+
+public:
+  ElfLNoteIteratorImpl(const ElfLNoteIteratorImpl &) = default;
+  virtual ~ElfLNoteIteratorImpl() = default;
+
+  static bool classof(const ElfLNoteIteratorImplBase *B) {
+    return (B->getEndianness() == ELFT::TargetEndianness &&
+            B->is64Bits() == ELFT::Is64Bits);
+  }
+};
+
+template <class ELFT>
+class ElfLSectionNoteIteratorImpl : public ElfLNoteIteratorImpl<ELFT> {
+  using Elf_Shdr = typename ELFT::Shdr;
+  using Elf_Shdr_Range = typename ELFT::ShdrRange;
+  using NoteIterator = typename ElfLNoteIteratorImpl<ELFT>::NoteIterator;
+  using SectionsIteratorTy = typename Elf_Shdr_Range::iterator;
+
+  SectionsIteratorTy SectionsIt;
+
+  const ELFFile<ELFT> &getEF() const { return this->EF; }
+  const NoteIterator &getNotesIt() const { return this->NotesIt; }
+  Error &getErr() const { return this->Err; }
+  NoteIterator &getNotesIt() { return this->NotesIt; }
+  SectionsIteratorTy section_begin() const {
+    Expected<Elf_Shdr_Range> Sections = getEF().sections();
+    if (!Sections)
+      return SectionsIteratorTy();
+
+    return Sections->begin();
+  }
+
+  SectionsIteratorTy section_end() const {
+    Expected<Elf_Shdr_Range> Sections = getEF().sections();
+    if (!Sections)
+      return SectionsIteratorTy();
+
+    return Sections->end();
+  }
+
+  bool isEqual(const ElfLSectionNoteIteratorImpl &Lhs,
+               const ElfLSectionNoteIteratorImpl &Rhs) const {
+    // Check for end() iterators, first.
+    if (Lhs.SectionsIt == section_end() && Rhs.SectionsIt == section_end())
+      return true;
+
+    if (Lhs.SectionsIt != Rhs.SectionsIt)
+      return false;
+
+    return Lhs.getNotesIt() == Rhs.getNotesIt();
+  }
+
+  void autoAdvance(bool IsFirst = false) {
+    if (SectionsIt == section_end())
+      return;
+
+    if (getNotesIt() != getEF().notes_end())
+      return;
+
+    // SectionsIt is not an end iterator, and NotesIt is an end()
+    // iterator.
+    //
+    // If IsFirst is true, then we just in the initial state, and
+    // we need to set SectionsIt to the first SHT_NOTE section (if any),
+    // and, then, NotesIt to the first note in this section.
+    //
+    // If IsFirst is false, then we've reached the end of the current
+    // SHT_NOTE section, and should find the next section with notes.
+    if (!IsFirst || SectionsIt->sh_type != ELF::SHT_NOTE)
+      ++SectionsIt;
+
+    while (SectionsIt != section_end() &&
+           SectionsIt->sh_type != ELF::SHT_NOTE) {
+      ++SectionsIt;
+    }
+
+    if (SectionsIt == section_end()) {
+      // No more sections.
+      return;
+    }
+
+    const Elf_Shdr &Section = *SectionsIt;
+    getNotesIt() = getEF().notes_begin(Section, getErr());
+
+    // Auto advance the iterator, if the NOTE section
+    // does not contain any notes (e.g. some error happened
+    // during the note parsing).
+    autoAdvance();
+  }
+
+  bool operator!=(const ElfLSectionNoteIteratorImpl &Other) const {
+    return !(*this == Other);
+  }
+
+public:
+  ElfLSectionNoteIteratorImpl(const ELFFile<ELFT> &EF, Error &Err,
+                              bool IsEnd = false)
+      : ElfLNoteIteratorImpl<ELFT>(EF, Err, true) {
+    if (IsEnd) {
+      SectionsIt = section_end();
+      // It is an end() iterator, if SectionsIt is an end() iterator.
+      return;
+    }
+
+    SectionsIt = section_begin();
+    autoAdvance(true);
+  }
+
+  ElfLSectionNoteIteratorImpl(const ElfLSectionNoteIteratorImpl &Copy) =
+      default;
+
+  ElfLNoteIteratorImplBase *clone() const override {
+    return new ElfLSectionNoteIteratorImpl(*this);
+  }
+
+  bool operator==(const ElfLNoteIteratorImplBase &Other) const override {
+    if (const ElfLSectionNoteIteratorImpl *OPtr =
+            dyn_cast<const ElfLSectionNoteIteratorImpl>(&Other)) {
+      return isEqual(*this, *OPtr);
+    }
+    return false;
+  }
+
+  ElfLSectionNoteIteratorImpl &operator++() override {
+    assert(*this != ElfLSectionNoteIteratorImpl(getEF(), getErr(), true) &&
+           "Incrementing the end iterator.");
+    // Move the notes iterator within the current section.
+    ++getNotesIt();
+    autoAdvance();
+
+    return *this;
+  }
+
+  ElfLNoteImplBase *operator*() const override {
+    assert(*this != ElfLSectionNoteIteratorImpl(getEF(), getErr(), true) &&
+           "Dereferencing the end iterator.");
+    return new ElfLNoteImpl<ELFT>(*getNotesIt());
+  }
+
+  static bool classof(const ElfLNoteIteratorImplBase *B) {
+    return (ElfLNoteIteratorImpl<ELFT>::classof(B) &&
+            B->isSectionIterator() == true);
+  }
+};
+
+template <class ELFT>
+class ElfLSegmentNoteIteratorImpl : public ElfLNoteIteratorImpl<ELFT> {
+  using Elf_Phdr = typename ELFT::Phdr;
+  using Elf_Phdr_Range = typename ELFT::PhdrRange;
+  using NoteIterator = typename ElfLNoteIteratorImpl<ELFT>::NoteIterator;
+  using SegmentIteratorTy = typename Elf_Phdr_Range::iterator;
+
+  SegmentIteratorTy SegmentsIt;
+
+  const ELFFile<ELFT> &getEF() const { return this->EF; }
+  const NoteIterator &getNotesIt() const { return this->NotesIt; }
+  Error &getErr() const { return this->Err; }
+  NoteIterator &getNotesIt() { return this->NotesIt; }
+  SegmentIteratorTy segment_begin() const {
+    Expected<Elf_Phdr_Range> Segments = getEF().program_headers();
+    if (!Segments)
+      return SegmentIteratorTy();
+
+    return Segments->begin();
+  }
+
+  SegmentIteratorTy segment_end() const {
+    Expected<Elf_Phdr_Range> Segments = getEF().program_headers();
+    if (!Segments)
+      return SegmentIteratorTy();
+
+    return Segments->end();
+  }
+
+  bool isEqual(const ElfLSegmentNoteIteratorImpl &Lhs,
+               const ElfLSegmentNoteIteratorImpl &Rhs) const {
+    // Check for end() iterators, first.
+    if (Lhs.SegmentsIt == segment_end() && Rhs.SegmentsIt == segment_end())
+      return true;
+
+    if (Lhs.SegmentsIt != Rhs.SegmentsIt)
+      return false;
+
+    return Lhs.getNotesIt() == Rhs.getNotesIt();
+  }
+
+  void autoAdvance(bool IsFirst = false) {
+    if (SegmentsIt == segment_end())
+      return;
+
+    if (getNotesIt() != getEF().notes_end())
+      return;
+
+    // SegmentsIt is not an end iterator, and NotesIt is an end()
+    // iterator.
+    //
+    // If IsFirst is true, then we just in the initial state, and
+    // we need to set SegmentsIt to the first PT_NOTE segment (if any),
+    // and, then, NotesIt to the first note in this segment.
+    //
+    // If IsFirst is false, then we've reached the end of the current
+    // PT_NOTE segment, and should find the next segment with notes.
+    if (!IsFirst || SegmentsIt->p_type != ELF::SHT_NOTE)
+      ++SegmentsIt;
+
+    while (SegmentsIt != segment_end() && SegmentsIt->p_type != ELF::PT_NOTE) {
+      ++SegmentsIt;
+    }
+
+    if (SegmentsIt == segment_end()) {
+      // No more segments.
+      return;
+    }
+
+    const Elf_Phdr &Segment = *SegmentsIt;
+    getNotesIt() = getEF().notes_begin(Segment, getErr());
+
+    // Auto advance the iterator, if the NOTE segment
+    // does not contain any notes (e.g. some error happened
+    // during the note parsing).
+    autoAdvance();
+  }
+
+  bool operator!=(const ElfLSegmentNoteIteratorImpl &Other) const {
+    return !(*this == Other);
+  }
+
+public:
+  ElfLSegmentNoteIteratorImpl(const ELFFile<ELFT> &EF, Error &Err,
+                              bool IsEnd = false)
+      : ElfLNoteIteratorImpl<ELFT>(EF, Err, false) {
+    if (IsEnd) {
+      SegmentsIt = segment_end();
+      // It is an end() iterator, if SegmentsIt is an end() iterator.
+      return;
+    }
+
+    SegmentsIt = segment_begin();
+    autoAdvance(true);
+  }
+
+  ElfLSegmentNoteIteratorImpl(const ElfLSegmentNoteIteratorImpl &Copy) =
+      default;
+
+  ElfLNoteIteratorImplBase *clone() const override {
+    return new ElfLSegmentNoteIteratorImpl(*this);
+  }
+
+  bool operator==(const ElfLNoteIteratorImplBase &Other) const override {
+    if (const ElfLSegmentNoteIteratorImpl *OPtr =
+            dyn_cast<const ElfLSegmentNoteIteratorImpl>(&Other)) {
+      return isEqual(*this, *OPtr);
+    }
+    return false;
+  }
+
+  ElfLSegmentNoteIteratorImpl &operator++() override {
+    assert(*this != ElfLSegmentNoteIteratorImpl(getEF(), getErr(), true) &&
+           "Incrementing the end iterator.");
+    // Move the notes iterator within the current segment.
+    ++getNotesIt();
+    autoAdvance();
+
+    return *this;
+  }
+
+  ElfLNoteImplBase *operator*() const override {
+    assert(*this != ElfLSegmentNoteIteratorImpl(getEF(), getErr(), true) &&
+           "Dereferencing the end iterator.");
+    return new ElfLNoteImpl<ELFT>(*getNotesIt());
+  }
+
+  static bool classof(const ElfLNoteIteratorImplBase *B) {
+    return (ElfLNoteIteratorImpl<ELFT>::classof(B) &&
+            B->isSectionIterator() == false);
+  }
+};
+
+class ElfLImplBase {
+public:
+  ElfLImplBase() = default;
+  ElfLImplBase(const ElfLImplBase &) = delete;
+  ElfLImplBase &operator=(const ElfLImplBase &) = delete;
+  virtual ~ElfLImplBase() = default;
+  virtual uint16_t getEMachine() const = 0;
+  virtual uint16_t getEType() const = 0;
+
+  virtual ElfLNoteIteratorImplBase *
+  createSectionNoteIteratorImpl(bool IsEnd) const = 0;
+  virtual ElfLNoteIteratorImplBase *
+  createSegmentNoteIteratorImpl(bool IsEnd) const = 0;
+};
+
+template <class ELFT> class ElfLImpl : public ElfLImplBase {
+  std::unique_ptr<ELFObjectFile<ELFT>> File;
+  Error *Err = nullptr;
+
+  friend class ElfL;
+
+public:
+  ElfLImpl(std::unique_ptr<ObjectFile> F) {
+    ObjectFile *FPtr = F.release();
+    if (auto *Obj = dyn_cast<ELFObjectFile<ELFT>>(FPtr))
+      File = std::unique_ptr<ELFObjectFile<ELFT>>(Obj);
+    else
+      assert(false && "Not an ELF object file, or ELF class is wrong.");
+
+    Err = new Error(std::move(Error::success()));
+  }
+  ElfLImpl(const ElfLImpl &) = delete;
+  ElfLImpl &operator=(const ElfLImpl &) = delete;
+  virtual ~ElfLImpl() {
+    if (!Err)
+      return;
+
+    if (*Err) {
+      auto ErrorString = toString(std::move(*Err));
+      DP("Destroying ELF object parsed with errors: %s\n", ErrorString.c_str());
+    } else {
+      delete Err;
+    }
+    Err = nullptr;
+  }
+  uint16_t getEMachine() const override {
+    return cast<ELFObjectFileBase>(File.get())->getEMachine();
+  }
+  uint16_t getEType() const override {
+    return cast<ELFObjectFileBase>(File.get())->getEType();
+  }
+
+  ElfLNoteIteratorImplBase *
+  createSectionNoteIteratorImpl(bool IsEnd) const override {
+    return new ElfLSectionNoteIteratorImpl<ELFT>(File->getELFFile(), *Err,
+                                                 IsEnd);
+  }
+
+  ElfLNoteIteratorImplBase *
+  createSegmentNoteIteratorImpl(bool IsEnd) const override {
+    return new ElfLSegmentNoteIteratorImpl<ELFT>(File->getELFFile(), *Err,
+                                                 IsEnd);
+  }
+};
+
+ElfL::ElfL(char *Begin, size_t Size) {
+  StringRef StrBuf(Begin, Size);
+  std::unique_ptr<MemoryBuffer> MemBuf =
+      MemoryBuffer::getMemBuffer(StrBuf, "", false);
+  Expected<std::unique_ptr<ObjectFile>> BinOrErr =
+      ObjectFile::createELFObjectFile(MemBuf->getMemBufferRef(),
+                                      /*InitContent=*/false);
+  if (!BinOrErr)
+    return;
+
+  if (isa<ELF64LEObjectFile>(BinOrErr->get())) {
+    Impl =
+        reinterpret_cast<void *>(new ElfLImpl<ELF64LE>(std::move(*BinOrErr)));
+  } else if (isa<ELF32LEObjectFile>(BinOrErr->get()))
+    Impl =
+        reinterpret_cast<void *>(new ElfLImpl<ELF32LE>(std::move(*BinOrErr)));
+  else if (isa<ELF32BEObjectFile>(BinOrErr->get()))
+    Impl =
+        reinterpret_cast<void *>(new ElfLImpl<ELF32BE>(std::move(*BinOrErr)));
+  else if (isa<ELF64BEObjectFile>(BinOrErr->get()))
+    Impl =
+        reinterpret_cast<void *>(new ElfLImpl<ELF64BE>(std::move(*BinOrErr)));
+}
+
+ElfL::~ElfL() {
+  ElfLImplBase *EImpl = reinterpret_cast<ElfLImplBase *>(Impl);
+  delete EImpl;
+}
+
+bool ElfL::isValidElf() const { return Impl; }
+
+const char *ElfL::getErrmsg(int N) const { return "LLVM ELF error"; }
+
+uint16_t ElfL::getEMachine() const {
+  assert(isValidElf() && "Invalid ELF.");
+  ElfLImplBase *EImpl = reinterpret_cast<ElfLImplBase *>(Impl);
+  return EImpl->getEMachine();
+}
+
+uint16_t ElfL::getEType() const {
+  assert(isValidElf() && "Invalid ELF.");
+  ElfLImplBase *EImpl = reinterpret_cast<ElfLImplBase *>(Impl);
+  return EImpl->getEType();
+}
+
+bool ElfL::isDynType(uint16_t Ty) { return Ty == ET_DYN; }
+
+ElfLSectionNoteIterator::ElfLSectionNoteIterator(const void *I, bool IsEnd) {
+  const ElfLImplBase *EImpl = reinterpret_cast<const ElfLImplBase *>(I);
+  // Create new ElfLSectionNoteIteratorImpl<ELFT> object.
+  Impl = EImpl->createSectionNoteIteratorImpl(IsEnd);
+}
+
+ElfLSectionNoteIterator::~ElfLSectionNoteIterator() {
+  const ElfLNoteIteratorImplBase *IImpl =
+      reinterpret_cast<const ElfLNoteIteratorImplBase *>(Impl);
+  delete IImpl;
+}
+
+ElfLSectionNoteIterator::ElfLSectionNoteIterator(
+    const ElfLSectionNoteIterator &Other) {
+  const ElfLNoteIteratorImplBase *IImpl =
+      reinterpret_cast<const ElfLNoteIteratorImplBase *>(Other.Impl);
+  Impl = IImpl->clone();
+}
+
+bool ElfLSectionNoteIterator::operator==(
+    const ElfLSectionNoteIterator Other) const {
+  const ElfLNoteIteratorImplBase *Lhs =
+      reinterpret_cast<const ElfLNoteIteratorImplBase *>(Impl);
+  const ElfLNoteIteratorImplBase *Rhs =
+      reinterpret_cast<const ElfLNoteIteratorImplBase *>(Other.Impl);
+  return (*Lhs == *Rhs);
+}
+
+bool ElfLSectionNoteIterator::operator!=(
+    const ElfLSectionNoteIterator Other) const {
+  return !(*this == Other);
+}
+
+ElfLSectionNoteIterator &ElfLSectionNoteIterator::operator++() {
+  ElfLNoteIteratorImplBase *EImpl =
+      reinterpret_cast<ElfLNoteIteratorImplBase *>(Impl);
+  ++(*EImpl);
+  return *this;
+}
+
+ElfLNote ElfLSectionNoteIterator::operator*() const { return ElfLNote(Impl); }
+
+ElfLSectionNoteIterator ElfL::section_notes_begin() const {
+  assert(isValidElf() && "Invalid ELF.");
+  return ElfLSectionNoteIterator(reinterpret_cast<const ElfLImplBase *>(Impl));
+}
+
+ElfLSectionNoteIterator ElfL::section_notes_end() const {
+  assert(isValidElf() && "Invalid ELF.");
+  return ElfLSectionNoteIterator(reinterpret_cast<const ElfLImplBase *>(Impl),
+                                 true);
+}
+
+ElfLSegmentNoteIterator::ElfLSegmentNoteIterator(const void *I, bool IsEnd) {
+  const ElfLImplBase *EImpl = reinterpret_cast<const ElfLImplBase *>(I);
+  // Create new ElfLSegmentNoteIteratorImpl<ELFT> object.
+  Impl = EImpl->createSegmentNoteIteratorImpl(IsEnd);
+}
+
+ElfLSegmentNoteIterator::~ElfLSegmentNoteIterator() {
+  const ElfLNoteIteratorImplBase *IImpl =
+      reinterpret_cast<const ElfLNoteIteratorImplBase *>(Impl);
+  delete IImpl;
+}
+
+ElfLSegmentNoteIterator::ElfLSegmentNoteIterator(
+    const ElfLSegmentNoteIterator &Other) {
+  const ElfLNoteIteratorImplBase *IImpl =
+      reinterpret_cast<const ElfLNoteIteratorImplBase *>(Other.Impl);
+  Impl = IImpl->clone();
+}
+
+bool ElfLSegmentNoteIterator::operator==(
+    const ElfLSegmentNoteIterator Other) const {
+  const ElfLNoteIteratorImplBase *Lhs =
+      reinterpret_cast<const ElfLNoteIteratorImplBase *>(Impl);
+  const ElfLNoteIteratorImplBase *Rhs =
+      reinterpret_cast<const ElfLNoteIteratorImplBase *>(Other.Impl);
+  return (*Lhs == *Rhs);
+}
+
+bool ElfLSegmentNoteIterator::operator!=(
+    const ElfLSegmentNoteIterator Other) const {
+  return !(*this == Other);
+}
+
+ElfLSegmentNoteIterator &ElfLSegmentNoteIterator::operator++() {
+  ElfLNoteIteratorImplBase *EImpl =
+      reinterpret_cast<ElfLNoteIteratorImplBase *>(Impl);
+  ++(*EImpl);
+  return *this;
+}
+
+ElfLNote ElfLSegmentNoteIterator::operator*() const { return ElfLNote(Impl); }
+
+ElfLSegmentNoteIterator ElfL::segment_notes_begin() const {
+  assert(isValidElf() && "Invalid ELF.");
+  return ElfLSegmentNoteIterator(reinterpret_cast<const ElfLImplBase *>(Impl));
+}
+
+ElfLSegmentNoteIterator ElfL::segment_notes_end() const {
+  assert(isValidElf() && "Invalid ELF.");
+  return ElfLSegmentNoteIterator(reinterpret_cast<const ElfLImplBase *>(Impl),
+                                 true);
+}
+
+ElfLNote::ElfLNote(const void *IteratorImpl) {
+  const ElfLNoteIteratorImplBase *IImpl =
+      reinterpret_cast<const ElfLNoteIteratorImplBase *>(IteratorImpl);
+  Impl = **IImpl;
+}
+
+ElfLNote::ElfLNote(const ElfLNote &Other) {
+  const ElfLNoteImplBase *NImpl =
+      reinterpret_cast<const ElfLNoteImplBase *>(Impl);
+  Impl = NImpl->clone();
+}
+
+ElfLNote::~ElfLNote() {
+  const ElfLNoteImplBase *NImpl =
+      reinterpret_cast<const ElfLNoteImplBase *>(Impl);
+  delete NImpl;
+}
+
+uint64_t ElfLNote::getNameSize() const {
+  const ElfLNoteImplBase *NImpl =
+      reinterpret_cast<const ElfLNoteImplBase *>(Impl);
+  return NImpl->getNameSize();
+}
+
+const char *ElfLNote::getName() const {
+  const ElfLNoteImplBase *NImpl =
+      reinterpret_cast<const ElfLNoteImplBase *>(Impl);
+  return NImpl->getName();
+}
+
+uint64_t ElfLNote::getDescSize() const {
+  const ElfLNoteImplBase *NImpl =
+      reinterpret_cast<const ElfLNoteImplBase *>(Impl);
+  return NImpl->getDescSize();
+}
+
+const uint8_t *ElfLNote::getDesc() const {
+  const ElfLNoteImplBase *NImpl =
+      reinterpret_cast<const ElfLNoteImplBase *>(Impl);
+  return NImpl->getDesc();
+}
+
+uint64_t ElfLNote::getType() const {
+  const ElfLNoteImplBase *NImpl =
+      reinterpret_cast<const ElfLNoteImplBase *>(Impl);
+  return NImpl->getType();
+}
+#endif // !MAY_USE_LIBELF

openmp/libomptarget/plugins/remote/server/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 server for remote offloading.
 #
 ##===----------------------------------------------------------------------===##
 
-include_directories(${LIBOMPTARGET_DEP_LIBELF_INCLUDE_DIRS})
 include_directories(${LIBOMPTARGET_SRC_DIR})
 include_directories(${LIBOMPTARGET_INCLUDE_DIR})
 include_directories(${GRPC_INCLUDE_DIR})
 include_directories(${RPC_INCLUDE_DIR})
 
 add_executable(openmp-offloading-server
         ${LIBOMPTARGET_SRC_FILES}
         ${GRPC_SRC_FILES}
         ${RPC_SRC_DIR}/Utils.cpp
         Server.cpp
         OffloadingServer.cpp
 )
 
 target_link_libraries(openmp-offloading-server
         grpc++
         protobuf
         ${OPENMP_PTHREAD_LIB}
-        "-ldl" "-lomp" "-fopenmp" "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/../../exports" ${LIBOMPTARGET_DEP_LIBELF_LIBRARIES})
+        "-ldl" "-lomp" "-fopenmp" "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/../../exports")

openmp/libomptarget/test/offloading/llvmompoffload_notes.c

+// RUN: %libomptarget-compile-x86_64-pc-linux-gnu && env LIBOMPTARGET_DEBUG=1 %libomptarget-run-x86_64-pc-linux-gnu 2>&1 | %fcheck-x86_64-pc-linux-gnu
+
+// CHECK: TARGET Common ELF --> LLVMOMPOFFLOAD ELF note NT_LLVM_OPENMP_OFFLOAD_VERSION with value: '1.0'
+// CHECK: TARGET Common ELF --> LLVMOMPOFFLOAD ELF note NT_LLVM_OPENMP_OFFLOAD_PRODUCER with value: 'LLVM'
+// CHECK: TARGET Common ELF --> LLVMOMPOFFLOAD ELF note NT_LLVM_OPENMP_OFFLOAD_PRODUCER_VERSION with value:
+
+int main() {
+#pragma omp target
+  ;
+
+  return 0;
+}