Added preliminary implementation of generic object serialization to bitcode.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43261 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Bitcode/Reader/Deserialize.cpp

@@ -0,0 +1,83 @@
+//==- Deserialize.cpp - Generic Object Serialization to Bitcode --*- C++ -*-==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Ted Kremenek and is distributed under the
+// University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the internal methods used for object serialization.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Bitcode/Serialization.h"
+
+using namespace llvm;
+
+Deserializer::Deserializer(BitstreamReader& stream)
+  : Stream(stream), RecIdx(0) {
+}
+
+Deserializer::~Deserializer() {
+  assert (RecIdx >= Record.size() && 
+          "Still scanning bitcode record when deserialization completed.");
+}
+
+void Deserializer::ReadRecord() {
+  // FIXME: Check if we haven't run off the edge of the stream.
+  // FIXME: Handle abbreviations.
+  unsigned Code = Stream.ReadCode();
+  // FIXME: Check for the correct code.
+  assert (Record.size() == 0);
+  
+  Stream.ReadRecord(Code,Record);
+  
+  assert (Record.size() > 0);
+}
+
+uint64_t Deserializer::ReadInt(unsigned Bits) {
+  // FIXME: Any error recovery/handling with incomplete or bad files?
+  if (!inRecord())
+    ReadRecord();
+
+  // FIXME: check for loss of precision in read (compare to Bits)
+  return Record[RecIdx++];
+}
+
+char* Deserializer::ReadCString(char* cstr, unsigned MaxLen, bool isNullTerm) {
+  if (cstr == NULL)
+    MaxLen = 0; // Zero this just in case someone does something funny.
+  
+  unsigned len = ReadInt(32);
+
+  // FIXME: perform dynamic checking of lengths?
+  assert (MaxLen == 0 || (len + (isNullTerm ? 1 : 0)) <= MaxLen);
+
+  if (!cstr)
+    cstr = new char[len + (isNullTerm ? 1 : 0)];
+  
+  assert (cstr != NULL);
+  
+  for (unsigned i = 0; i < len; ++i)
+    cstr[i] = ReadInt(8);
+  
+  if (isNullTerm)
+    cstr[len+1] = '\0';
+  
+  return cstr;
+}
+
+void Deserializer::ReadCString(std::vector<char>& buff, bool isNullTerm) {
+  buff.clear();
+
+  unsigned len = ReadInt(32);
+  
+  buff.reserve(len);
+  
+  for (unsigned i = 0; i < len; ++i)
+    buff.push_back(ReadInt(8));
+  
+  if (isNullTerm)
+    buff.push_back('\0');
+}