[EVM] Adding lld-c API to lld-as-library functionality.

lld/CMakeLists.txt

@@ -246,6 +246,7 @@ if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
     )
 endif()
 
+add_subdirectory(lld-c)
 add_subdirectory(Common)
 add_subdirectory(tools/lld)
 

lld/include/lld-c/LLDAsLibraryC.h

@@ -0,0 +1,31 @@
+//==----- EVMFrameLowering.h - Define frame lowering for EVM --*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This header declares the C interface to the lld-as-a-library, which can be
+// used to invoke LLD functionality.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLD_C_LLDASLIBRARYC_H
+#define LLD_C_LLDASLIBRARYC_H
+
+#include "llvm-c/ExternC.h"
+#include "llvm-c/Types.h"
+
+LLVM_C_EXTERN_C_BEGIN
+
+/** Performs linkage a operation of an object code via lld-as-a-library.
+    Input/output files are transferred via memory buffers. */
+
+LLVMBool llvmLinkMemoryBuffers(LLVMMemoryBufferRef *inMemBufs, size_t numInBufs,
+                               LLVMMemoryBufferRef *outMemBuf,
+                               const char **lldArgs, size_t numLldArgs);
+
+LLVM_C_EXTERN_C_END
+
+#endif // LLD_C_LLDASLIBRARYC_H

lld/lld-c/CMakeLists.txt

@@ -0,0 +1,11 @@
+add_lld_library(lldC
+  LLDAsLibraryC.cpp
+
+  ${LLD_INCLUDE_DIR}/lld/Common
+
+  LINK_COMPONENTS
+  Core
+
+  DEPENDS
+  intrinsics_gen
+  )

lld/lld-c/LLDAsLibraryC.cpp

@@ -0,0 +1,30 @@
+#include "lld-c/LLDAsLibraryC.h"
+#include "lld/Common/Driver.h"
+#include "lld/Common/ErrorHandler.h"
+#include "llvm-c/Core.h"
+#include "llvm/Support/MemoryBuffer.h"
+
+LLD_HAS_DRIVER_MEM_BUF(elf)
+
+LLVMBool llvmLinkMemoryBuffers(LLVMMemoryBufferRef *inMemBufs, size_t numInBufs,
+                               LLVMMemoryBufferRef *outMemBuf,
+                               const char **lldArgs, size_t numLldArgs) {
+  llvm::SmallVector<llvm::MemoryBufferRef> inData(numInBufs);
+  for (unsigned idx = 0; idx < numInBufs; ++idx)
+    inData[idx] = *llvm::unwrap(inMemBufs[idx]);
+
+  llvm::SmallVector<const char *> args(numLldArgs);
+  for (unsigned idx = 0; idx < numLldArgs; ++idx)
+    args[idx] = lldArgs[idx];
+
+  llvm::SmallString<0> codeString;
+  llvm::raw_svector_ostream ostream(codeString);
+  const lld::Result s =
+      lld::lldMainMemBuf(inData, &ostream, args, llvm::outs(), llvm::errs(),
+                         {{lld::Gnu, &lld::elf::linkMemBuf}});
+  llvm::StringRef data = ostream.str();
+  *outMemBuf =
+      LLVMCreateMemoryBufferWithMemoryRangeCopy(data.data(), data.size(), "");
+
+  return !s.retCode && s.canRunAgain;
+}