[LLVM-C] Begin to Expose A More General Binary Interface

Summary:
Provides a new type, `LLVMBinaryRef`, and a binding to `llvm::object::createBinary` for more general interoperation with binary files than `LLVMObjectFileRef`.  It also provides the proper non-consuming API for input buffers and populates an out parameter for error handling if necessary - two things the previous API did not do.

In a follow-up, I'll define section and symbol iterators and begin to build upon the existing test infrastructure.

This patch is a first step towards deprecating that API and replacing it with something more robust.

Reviewers: deadalnix, whitequark

Reviewed By: whitequark

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60322

llvm-svn: 357822

llvm/include/llvm-c/Object.h

@@ -39,6 +39,45 @@ typedef struct LLVMOpaqueSectionIterator *LLVMSectionIteratorRef;
 typedef struct LLVMOpaqueSymbolIterator *LLVMSymbolIteratorRef;
 typedef struct LLVMOpaqueRelocationIterator *LLVMRelocationIteratorRef;
 
+/**
+ * Create a binary file from the given memory buffer.
+ *
+ * The exact type of the binary file will be inferred automatically, and the
+ * appropriate implementation selected.  The context may be NULL except if
+ * the resulting file is an LLVM IR file.
+ *
+ * The memory buffer is not consumed by this function.  It is the responsibilty
+ * of the caller to free it with \c LLVMDisposeMemoryBuffer.
+ *
+ * If NULL is returned, the \p ErrorMessage parameter is populated with the
+ * error's description.  It is then the caller's responsibility to free this
+ * message by calling \c LLVMDisposeMessage.
+ *
+ * @see llvm::object::createBinary
+ */
+LLVMBinaryRef LLVMCreateBinary(LLVMMemoryBufferRef MemBuf,
+                               LLVMContextRef Context,
+                               char **ErrorMessage);
+
+/**
+ * Dispose of a binary file.
+ *
+ * The binary file does not own its backing buffer.  It is the responsibilty
+ * of the caller to free it with \c LLVMDisposeMemoryBuffer.
+ */
+void LLVMDisposeBinary(LLVMBinaryRef BR);
+
+/**
+ * Retrieves a copy of the memory buffer associated with this object file.
+ *
+ * The returned buffer is merely a shallow copy and does not own the actual
+ * backing buffer of the binary. Nevertheless, it is the responsibility of the
+ * caller to free it with \c LLVMDisposeMemoryBuffer.
+ *
+ * @see llvm::object::getMemoryBufferRef
+ */
+LLVMMemoryBufferRef LLVMBinaryCopyMemoryBuffer(LLVMBinaryRef BR);
+
 // ObjectFile creation
 LLVMObjectFileRef LLVMCreateObjectFile(LLVMMemoryBufferRef MemBuf);
 void LLVMDisposeObjectFile(LLVMObjectFileRef ObjectFile);

llvm/include/llvm-c/Types.h

@@ -163,6 +163,11 @@ typedef struct LLVMOpaqueModuleFlagEntry LLVMModuleFlagEntry;
  */
 typedef struct LLVMOpaqueJITEventListener *LLVMJITEventListenerRef;
 
+/**
+ * @see llvm::object::Binary
+ */
+typedef struct LLVMOpaqueBinary *LLVMBinaryRef;
+
 /**
  * @}
  */

llvm/include/llvm/Object/Binary.h

@@ -13,6 +13,7 @@
 #ifndef LLVM_OBJECT_BINARY_H
 #define LLVM_OBJECT_BINARY_H
 
+#include "llvm-c/Types.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/Object/Error.h"
 #include "llvm/Support/Error.h"
@@ -162,6 +163,9 @@ public:
   }
 };
 
+// Create wrappers for C Binding types (see CBindingWrapping.h).
+DEFINE_ISA_CONVERSION_FUNCTIONS(Binary, LLVMBinaryRef)
+
 /// Create a Binary from Source, autodetecting the file type.
 ///
 /// @param Source The data to create the Binary from.

llvm/lib/Object/Object.cpp

@@ -13,6 +13,7 @@
 
 #include "llvm-c/Object.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/IR/LLVMContext.h"
 #include "llvm/Object/ObjectFile.h"
 
 using namespace llvm;
@@ -57,6 +58,33 @@ wrap(const relocation_iterator *SI) {
     (const_cast<relocation_iterator*>(SI));
 }
 
+/*--.. Operations on binary files ..........................................--*/
+
+LLVMBinaryRef LLVMCreateBinary(LLVMMemoryBufferRef MemBuf,
+                               LLVMContextRef Context,
+                               char **ErrorMessage) {
+  auto maybeContext = Context ? unwrap(Context) : nullptr;
+  Expected<std::unique_ptr<Binary>> ObjOrErr(
+      createBinary(unwrap(MemBuf)->getMemBufferRef(), maybeContext));
+  if (!ObjOrErr) {
+    *ErrorMessage = strdup(toString(ObjOrErr.takeError()).c_str());
+    return nullptr;
+  }
+
+  return wrap(ObjOrErr.get().release());
+}
+
+LLVMMemoryBufferRef LLVMBinaryCopyMemoryBuffer(LLVMBinaryRef BR) {
+  auto Buf = unwrap(BR)->getMemoryBufferRef();
+  return wrap(llvm::MemoryBuffer::getMemBuffer(
+                Buf.getBuffer(), Buf.getBufferIdentifier(),
+                /*RequiresNullTerminator*/false).release());
+}
+
+void LLVMDisposeBinary(LLVMBinaryRef BR) {
+  delete unwrap(BR);
+}
+
 // ObjectFile creation
 LLVMObjectFileRef LLVMCreateObjectFile(LLVMMemoryBufferRef MemBuf) {
   std::unique_ptr<MemoryBuffer> Buf(unwrap(MemBuf));