[clang] [Clang][SYCL] Introduce clang-sycl-link-wrapper to link SYCL offloading device code (Part 1 of many) (PR #112245)

[Joseph Huber via cfe-commits]

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+//=-- clang-sycl-link-wrapper/ClangSYCLLinkWrapper.cpp - SYCL linker util --=//
+//
+// 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
+//
+//===---------------------------------------------------------------------===//
+//
+// This tool wraps around the sequence of steps required to link device code in
+// SYCL fat objects. SYCL device code linking requires a complex sequence of
+// steps that include linking of llvm bitcode files, linking device library
+// files with the fully linked source bitcode file(s), running several SYCL
+// specific post-link steps on the fully linked bitcode file(s), and finally
+// generating target-specific device code. This tool can be removed once SYCL
+// linking is ported to `ld.lld`.
+//
+//===---------------------------------------------------------------------===//
+
+#include "clang/Basic/Version.h"
+
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/BinaryFormat/Magic.h"
+#include "llvm/Bitcode/BitcodeWriter.h"
+#include "llvm/CodeGen/CommandFlags.h"
+#include "llvm/IR/DiagnosticPrinter.h"
+#include "llvm/IRReader/IRReader.h"
+#include "llvm/LTO/LTO.h"
+#include "llvm/Object/Archive.h"
+#include "llvm/Object/ArchiveWriter.h"
+#include "llvm/Object/Binary.h"
+#include "llvm/Object/ELFObjectFile.h"
+#include "llvm/Object/IRObjectFile.h"
+#include "llvm/Object/ObjectFile.h"
+#include "llvm/Object/OffloadBinary.h"
+#include "llvm/Option/ArgList.h"
+#include "llvm/Option/OptTable.h"
+#include "llvm/Option/Option.h"
+#include "llvm/Remarks/HotnessThresholdParser.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/FileOutputBuffer.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/InitLLVM.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/Program.h"
+#include "llvm/Support/Signals.h"
+#include "llvm/Support/StringSaver.h"
+#include "llvm/Support/TargetSelect.h"
+#include "llvm/Support/TimeProfiler.h"
+#include "llvm/Support/WithColor.h"
+
+using namespace llvm;
+using namespace llvm::opt;
+using namespace llvm::object;
+
+/// Save intermediary results.
+static bool SaveTemps = false;
+
+/// Print arguments without executing.
+static bool DryRun = false;
+
+/// Print verbose output.
+static bool Verbose = false;
+
+/// Filename of the output being created.
+static StringRef OutputFile;
+
+/// Directory to dump SPIR-V IR if requested by user.
+static SmallString<128> SPIRVDumpDir;
+
+static void printVersion(raw_ostream &OS) {
+  OS << clang::getClangToolFullVersion("clang-sycl-link-wrapper") << '\n';
+}
+
+/// The value of `argv[0]` when run.
+static const char *Executable;
+
+/// Temporary files to be cleaned up.
+static SmallVector<SmallString<128>> TempFiles;
+
+namespace {
+// Must not overlap with llvm::opt::DriverFlag.
+enum WrapperFlags { WrapperOnlyOption = (1 << 4) };
+
+enum ID {
+  OPT_INVALID = 0, // This is not an option ID.
+#define OPTION(...) LLVM_MAKE_OPT_ID(__VA_ARGS__),
+#include "SYCLLinkOpts.inc"
+  LastOption
+#undef OPTION
+};
+
+#define PREFIX(NAME, VALUE)                                                    \
+  static constexpr StringLiteral NAME##_init[] = VALUE;                        \
+  static constexpr ArrayRef<StringLiteral> NAME(NAME##_init,                   \
+                                                std::size(NAME##_init) - 1);
+#include "SYCLLinkOpts.inc"
+#undef PREFIX
+
+static constexpr OptTable::Info InfoTable[] = {
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jhuber6 wrote:

The thing that's special about this case is that it forwards arguments it doesn't understand via a flag. We could possibly make a utility for that.

https://github.com/llvm/llvm-project/pull/112245