[llvm-c] Expose IRReader interface

Original patch by Chris Wailes

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194137 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/IRReader/IRReader.cpp b/lib/IRReader/IRReader.cpp
index 656fe18..935e81d 100644
--- a/lib/IRReader/IRReader.cpp
+++ b/lib/IRReader/IRReader.cpp
@@ -11,10 +11,15 @@
 #include "llvm/ADT/OwningPtr.h"
 #include "llvm/Assembly/Parser.h"
 #include "llvm/Bitcode/ReaderWriter.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/system_error.h"
 #include "llvm/Support/Timer.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm-c/Core.h"
+#include "llvm-c/IRReader.h"
 
 using namespace llvm;
 
@@ -87,3 +92,30 @@
 
   return ParseIR(File.take(), Err, Context);
 }
+
+//===----------------------------------------------------------------------===//
+// C API.
+//===----------------------------------------------------------------------===//
+
+LLVMBool LLVMParseIRInContext(LLVMContextRef ContextRef,
+                              LLVMMemoryBufferRef MemBuf, LLVMModuleRef *OutM,
+                              char **OutMessage) {
+  SMDiagnostic Diag;
+
+  *OutM = wrap(ParseIR(unwrap(MemBuf), Diag, *unwrap(ContextRef)));
+
+  if(!*OutM) {
+    if (OutMessage) {
+      std::string buf;
+      raw_string_ostream os(buf);
+
+      Diag.print(NULL, os, false);
+      os.flush();
+
+      *OutMessage = strdup(buf.c_str());
+    }
+    return 1;
+  }
+
+  return 0;
+}