Add convenience functions for reading in LLVM IR that autodetect

and LLVM Assembly and LLVM Bitcode and automatically call the
corresponding reader.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80809 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/IRReader.h

@@ -0,0 +1,117 @@
+//===---- llvm/Support/IRReader.h - Reader for LLVM IR files ----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines functions for reading LLVM IR. They support both
+// Bitcode and Assembly, automatically detecting the input format.
+//
+// These functions must be defined in a header file in order to avoid
+// library dependencies, since they reference both Bitcode and Assembly
+// functions.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_IRREADER_H
+#define LLVM_SUPPORT_IRREADER_H
+
+#include "llvm/Assembly/Parser.h"
+#include "llvm/Bitcode/ReaderWriter.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/SourceMgr.h"
+#include "llvm/ModuleProvider.h"
+
+namespace llvm {
+
+  /// If the given MemoryBuffer holds a bitcode image, return a ModuleProvider
+  /// for it which does lazy deserialization of function bodies.  Otherwise,
+  /// attempt to parse it as LLVM Assembly and return a fully populated
+  /// ModuleProvider. This function *always* takes ownership of the given
+  /// MemoryBuffer.
+  inline ModuleProvider *getIRModuleProvider(MemoryBuffer *Buffer,
+                                             const std::string &Filename,
+                                             SMDiagnostic &Err,
+                                             LLVMContext &Context) {
+    if (isBitcode((const unsigned char *)Buffer->getBufferStart(),
+                  (const unsigned char *)Buffer->getBufferEnd())) {
+      std::string ErrMsg;
+      ModuleProvider *MP = getBitcodeModuleProvider(Buffer, Context, &ErrMsg);
+      if (MP == 0) {
+        Err = SMDiagnostic(Filename, -1, -1, ErrMsg, "");
+        // ParseBitcodeFile does not take ownership of the Buffer in the
+        // case of an error.
+        delete Buffer;
+      }
+      return MP;
+    }
+
+    Module *M = ParseAssembly(Buffer, Filename, 0, Err, Context);
+    if (M == 0)
+      return 0;
+    return new ExistingModuleProvider(M);
+  }
+
+  /// If the given file holds a bitcode image, return a ModuleProvider
+  /// for it which does lazy deserialization of function bodies.  Otherwise,
+  /// attempt to parse it as LLVM Assembly and return a fully populated
+  /// ModuleProvider.
+  inline ModuleProvider *getIRFileModuleProvider(const std::string &Filename,
+                                                 SMDiagnostic &Err,
+                                                 LLVMContext &Context) {
+    std::string ErrMsg;
+    MemoryBuffer *F = MemoryBuffer::getFileOrSTDIN(Filename.c_str(), &ErrMsg);
+    if (F == 0) {
+      Err = SMDiagnostic(Filename, -1, -1,
+                         "Could not open input file '" + Filename + "'", "");
+      return 0;
+    }
+
+    return getIRModuleProvider(F, Filename, Err, Context);
+  }
+
+  /// If the given MemoryBuffer holds a bitcode image, return a Module
+  /// for it.  Otherwise, attempt to parse it as LLVM Assembly and return
+  /// a Module for it. This function *always* takes ownership of the given
+  /// MemoryBuffer.
+  inline Module *ParseIR(MemoryBuffer *Buffer,
+                         const std::string &Filename,
+                         SMDiagnostic &Err,
+                         LLVMContext &Context) {
+    if (isBitcode((const unsigned char *)Buffer->getBufferStart(),
+                  (const unsigned char *)Buffer->getBufferEnd())) {
+      std::string ErrMsg;
+      Module *M = ParseBitcodeFile(Buffer, Context, &ErrMsg);
+      // ParseBitcodeFile does not take ownership of the Buffer.
+      delete Buffer;
+      if (M == 0)
+        Err = SMDiagnostic(Filename, -1, -1, ErrMsg, "");
+      return M;
+    }
+
+    return ParseAssembly(Buffer, Filename, 0, Err, Context);
+  }
+
+  /// If the given file holds a bitcode image, return a Module for it.
+  /// Otherwise, attempt to parse it as LLVM Assembly and return a Module
+  /// for it.
+  inline Module *ParseIRFile(const std::string &Filename,
+                             SMDiagnostic &Err,
+                             LLVMContext &Context) {
+    std::string ErrMsg;
+    MemoryBuffer *F = MemoryBuffer::getFileOrSTDIN(Filename.c_str(), &ErrMsg);
+    if (F == 0) {
+      Err = SMDiagnostic(Filename, -1, -1,
+                         "Could not open input file '" + Filename + "'", "");
+      return 0;
+    }
+
+    return ParseIR(F, Filename, Err, Context);
+  }
+
+}
+
+#endif