[PATCH] D116541: [OpenMP] Introduce new flag to change offloading driver pipeline

[Joseph Huber via Phabricator via cfe-commits]

jhuber6 created this revision.
jhuber6 added reviewers: jdoerfert, gregrodgers, JonChesterfield, ronlieb.
Herald added subscribers: ormris, dexonsmith, dang, guansong, hiraditya, yaxunl, mgorny.
jhuber6 requested review of this revision.
Herald added subscribers: llvm-commits, cfe-commits, sstefan1.
Herald added projects: clang, LLVM.

This patch introduces the `-fopenmp-new-driver` option which instructs
the compiler to use a new driver scheme for producing offloading code.
In this scheme we create a complete offloading object file and then pass
it as input to the host compilation phase. This will allow us to embed
the object code in the backend phase.

[OpenMP] Add a flag for embedding a file into the module

This patch adds support for a flag `-fembed-offload-binary` to embed a
file as an ELF section in the output by placing it in a global variable.
This can be used to bundle offloading files with the host binary so it
can be accessed by the linker. The section is named using the
`-fembed-offload-section` option.

[OpenMP] Embed device files into the host IR

This patch adds support for embedding the device object files into the
host IR to create a fat binary. Each offloading file will be inserted
into a section with the following naming format
`.llvm.offloading.<triple>.<arch>`.

[Clang] Introduce Clang Linker Wrapper Tool

This patch introduces a linker wrapper tool that allows us to preprocess
files before they are sent to the linker. This adds a dummy action and
job to the driver stage that builds the linker command as usual and then
replaces the command line with the wrapper tool.

[OpenMP] Add support for extracting device code in linker wrapper

This patchs add support for extracting device offloading code from the
linker's input files. If the file contains a section with the name
`.llvm.offloading.<triple>.<arch>` it will be extracted to a new
temporary file to be linked. Addtionally, the host file containing it
will have the section stripped so it does not remain in the executable
once linked.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D116541

Files:
  clang/include/clang/Basic/CodeGenOptions.h
  clang/include/clang/CodeGen/BackendUtil.h
  clang/include/clang/Driver/Action.h
  clang/include/clang/Driver/Driver.h
  clang/include/clang/Driver/Job.h
  clang/include/clang/Driver/Options.td
  clang/include/clang/Driver/ToolChain.h
  clang/lib/CodeGen/BackendUtil.cpp
  clang/lib/CodeGen/CodeGenAction.cpp
  clang/lib/Driver/Action.cpp
  clang/lib/Driver/Driver.cpp
  clang/lib/Driver/ToolChain.cpp
  clang/lib/Driver/ToolChains/Clang.cpp
  clang/lib/Driver/ToolChains/Clang.h
  clang/test/Driver/openmp-offload-gpu.c
  clang/test/Frontend/embed-object.ll
  clang/tools/CMakeLists.txt
  clang/tools/clang-linker-wrapper/CMakeLists.txt
  clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
  llvm/include/llvm/Bitcode/BitcodeWriter.h
  llvm/lib/Bitcode/Writer/BitcodeWriter.cpp

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