1 files changed, 75 insertions, 0 deletions
diff --git a/offload/plugins-nextgen/host/dynamic_ffi/ffi.cpp b/offload/plugins-nextgen/host/dynamic_ffi/ffi.cpp
new file mode 100644
index 000000000000..c586ad1c1969
--- /dev/null
+++ b/offload/plugins-nextgen/host/dynamic_ffi/ffi.cpp
@@ -0,0 +1,75 @@
+//===--- generic-elf-64bit/dynamic_ffi/ffi.cpp -------------------- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Implement subset of the FFI api by calling into the FFI library via dlopen
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/DynamicLibrary.h"
+
+#include "Shared/Debug.h"
+#include <memory>
+
+#include "DLWrap.h"
+#include "ffi.h"
+
+DLWRAP_INITIALIZE()
+
+DLWRAP(ffi_call, 4);
+DLWRAP(ffi_prep_cif, 5);
+
+DLWRAP_FINALIZE()
+
+ffi_type ffi_type_void;
+ffi_type ffi_type_pointer;
+
+// Name of the FFI shared library.
+constexpr const char *FFI_PATH = "libffi.so";
+
+#define DYNAMIC_FFI_SUCCESS 0
+#define DYNAMIC_FFI_FAIL 1
+
+// Initializes the dynamic FFI wrapper.
+uint32_t ffi_init() {
+  std::string ErrMsg;
+  auto DynlibHandle = std::make_unique<llvm::sys::DynamicLibrary>(
+      llvm::sys::DynamicLibrary::getPermanentLibrary(FFI_PATH, &ErrMsg));
+
+  if (!DynlibHandle->isValid()) {
+    DP("Unable to load library '%s': %s!\n", FFI_PATH, ErrMsg.c_str());
+    return DYNAMIC_FFI_FAIL;
+  }
+
+  for (size_t I = 0; I < dlwrap::size(); I++) {
+    const char *Sym = dlwrap::symbol(I);
+
+    void *P = DynlibHandle->getAddressOfSymbol(Sym);
+    if (P == nullptr) {
+      DP("Unable to find '%s' in '%s'!\n", Sym, FFI_PATH);
+      return DYNAMIC_FFI_FAIL;
+    }
+    DP("Implementing %s with dlsym(%s) -> %p\n", Sym, Sym, P);
+
+    *dlwrap::pointer(I) = P;
+  }
+
+#define DYNAMIC_INIT(SYMBOL)                                                   \
+  {                                                                            \
+    void *SymbolPtr = DynlibHandle->getAddressOfSymbol(#SYMBOL);               \
+    if (!SymbolPtr) {                                                          \
+      DP("Unable to find '%s' in '%s'!\n", #SYMBOL, FFI_PATH);                 \
+      return DYNAMIC_FFI_FAIL;                                                 \
+    }                                                                          \
+    SYMBOL = *reinterpret_cast<decltype(SYMBOL) *>(SymbolPtr);                 \
+  }
+  DYNAMIC_INIT(ffi_type_void);
+  DYNAMIC_INIT(ffi_type_pointer);
+#undef DYNAMIC_INIT
+
+  return DYNAMIC_FFI_SUCCESS;
+}