[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.

Depends on D116541

Reviewed By: JonChesterfield

Differential Revision: https://reviews.llvm.org/D116542

llvm/lib/Bitcode/Writer/BitcodeWriter.cpp

@@ -69,6 +69,7 @@
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/SHA1.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Utils/ModuleUtils.h"
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
@@ -4973,3 +4974,19 @@ void llvm::EmbedBitcodeInModule(llvm::Module &M, llvm::MemoryBufferRef Buf,
       llvm::ConstantArray::get(ATy, UsedArray), "llvm.compiler.used");
   NewUsed->setSection("llvm.metadata");
 }
+
+void llvm::EmbedBufferInModule(llvm::Module &M, llvm::MemoryBufferRef Buf,
+                               StringRef SectionName) {
+  ArrayRef<char> ModuleData =
+      ArrayRef<char>(Buf.getBufferStart(), Buf.getBufferSize());
+
+  // Embed the buffer into the module.
+  llvm::Constant *ModuleConstant =
+      llvm::ConstantDataArray::get(M.getContext(), ModuleData);
+  llvm::GlobalVariable *GV = new llvm::GlobalVariable(
+      M, ModuleConstant->getType(), true, llvm::GlobalValue::PrivateLinkage,
+      ModuleConstant, "llvm.embedded.object");
+  GV->setSection(SectionName);
+
+  appendToCompilerUsed(M, GV);
+}