Add abilities to generate bitcode buffers from munged bitcode.

lib/Bitcode/NaCl/TestUtils/NaClBitcodeMungeReader.cpp

Index: lib/Bitcode/NaCl/TestUtils/NaClBitcodeMungeReader.cpp
diff --git a/lib/Bitcode/NaCl/TestUtils/NaClBitcodeMungeReader.cpp b/lib/Bitcode/NaCl/TestUtils/NaClBitcodeMungeReader.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..6cab2f8ea08943a1cf6641cc9cc819acea66f2bd
--- /dev/null
+++ b/lib/Bitcode/NaCl/TestUtils/NaClBitcodeMungeReader.cpp
@@ -0,0 +1,157 @@
+//===- NaClBitcodeMungeReader.cpp - Read bitcode record list ----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Implements bitcode reader for NaClBitcodeRecordList and NaClMungedBitcode.
+
+#include "llvm/Bitcode/NaCl/NaClBitcodeMungeUtils.h"
+
+#include "llvm/Bitcode/NaCl/NaClBitcodeHeader.h"
+#include "llvm/Support/MemoryBuffer.h"
+
+using namespace llvm;
+
+namespace {
+
+class BitcodeParser;
+
+// \brief The state associated with parsing a bitcode buffer.
+class BitcodeParseState {
+  BitcodeParseState(const BitcodeParseState&) = delete;
+  BitcodeParseState &operator=(const BitcodeParseState&) = delete;
+public:
+  // \brief Construct the bitcode parse state.
+  //
+  // \param Parser The parser used to parse the bitcode.
+  // \param[out] Records Filled with parsed records.
+  BitcodeParseState(BitcodeParser *Parser,
+                    NaClBitcodeRecordList &Records);
+
+  // List to read records into.
+  NaClBitcodeRecordList &Records;
+  // Listener used to get abbreviations as they are read.
+  NaClBitcodeParserListener AbbrevListener;
+};
+
+// \brief The bitcode parser to extract bitcode records.
+class BitcodeParser : public NaClBitcodeParser {
+  BitcodeParser(const BitcodeParser &) = delete;
+  BitcodeParser &operator=(const BitcodeParser&) = delete;
+public:
+  // \brief Top-level constructor for a bitcode parser.
+  //
+  // \param Cursor The beginning position of the bitcode to parse.
+  // \param[out] Records Filled with parsed records.
+  BitcodeParser(NaClBitstreamCursor &Cursor,
+                NaClBitcodeRecordList &Records)
+      : NaClBitcodeParser(Cursor),
+        State(new BitcodeParseState(this, Records)) {
+    SetListener(&State->AbbrevListener);
+  }
+
+  ~BitcodeParser() override {
+    if (EnclosingParser == nullptr)
+      delete State;
+  }
+
+  bool ParseBlock(unsigned BlockID) override {
+    BitcodeParser NestedParser(BlockID, this);
+    return NestedParser.ParseThisBlock();
+  }
+
+  void EnterBlock(unsigned NumWords) override {
+    NaClRecordVector Values;
+    Values.push_back(GetBlockID());
+    Values.push_back(Record.GetCursor().getAbbrevIDWidth());
+    std::unique_ptr<NaClBitcodeAbbrevRecord> AbbrevRec(
+        new NaClBitcodeAbbrevRecord(naclbitc::ENTER_SUBBLOCK,
+                                    naclbitc::BLK_CODE_ENTER,
+                                    Values));
+    State->Records.push_back(std::move(AbbrevRec));
+  }
+
+  void ExitBlock() override {
+    NaClRecordVector Values;
+    std::unique_ptr<NaClBitcodeAbbrevRecord> AbbrevRec(
+        new NaClBitcodeAbbrevRecord(naclbitc::END_BLOCK,
+                                    naclbitc::BLK_CODE_EXIT,
+                                    Values));
+    State->Records.push_back(std::move(AbbrevRec));
+  }
+
+  void ProcessRecord() override {
+    std::unique_ptr<NaClBitcodeAbbrevRecord> AbbrevRec(
+        new NaClBitcodeAbbrevRecord(Record.GetAbbreviationIndex(),
+                                    Record.GetCode(),
+                                    Record.GetValues()));
+    State->Records.push_back(std::move(AbbrevRec));
+  }
+
+  void SetBID() override {
+    ProcessRecord();
+  }
+
+  void ProcessAbbreviation(unsigned BlockID,
+                           NaClBitCodeAbbrev *Abbrev,
+                           bool IsLocal) override {
+    ProcessRecord();
+  }
+
+private:
+  // \brief Nested constructor for blocks within the bitcode buffer.
+  //
+  // \param BlockID The identifying constant associated with the block.
+  // \param EnclosingParser The bitcode parser parsing the enclosing block.
+  BitcodeParser(unsigned BlockID, BitcodeParser *EnclosingParser)
+      : NaClBitcodeParser(BlockID, EnclosingParser),
+        State(EnclosingParser->State) {}
+
+  // The state of the bitcode parser.
+  BitcodeParseState* State;
+};
+
+BitcodeParseState::BitcodeParseState(BitcodeParser *Parser,
+                                     NaClBitcodeRecordList &Records)
+    : Records(Records), AbbrevListener(Parser) {}
+
+} // end of anonymous namespace
+
+void llvm::readNaClBitcodeRecordList(
+    NaClBitcodeRecordList &RecordList,
+    std::unique_ptr<MemoryBuffer> InputBuffer) {
+  if (InputBuffer->getBufferSize() % 4 != 0)
+    report_fatal_error(
+        "Bitcode stream must be a multiple of 4 bytes in length");
+
+  const unsigned char *BufPtr =
+      (const unsigned char *) InputBuffer->getBufferStart();
+  const unsigned char *EndBufPtr = BufPtr + InputBuffer->getBufferSize();
+  const unsigned char *HeaderPtr = BufPtr;
+
+  // Read header and verify it is good.
+  NaClBitcodeHeader Header;
+  if (Header.Read(HeaderPtr, EndBufPtr) || !Header.IsSupported())
+    report_fatal_error("Invalid PNaCl bitcode header.\n");
+
+  NaClBitstreamReader Reader(BufPtr, EndBufPtr, Header.getHeaderSize());
+  NaClBitstreamCursor Cursor(Reader);
+
+  // Parse the bitcode buffer.
+  BitcodeParser Parser(Cursor, RecordList);
+
+  while (!Cursor.AtEndOfStream()) {
+    if (Parser.Parse())
+      report_fatal_error("Malformed records founds, unable to continue");
+  }
+}
+
+
+NaClMungedBitcode::NaClMungedBitcode(std::unique_ptr<MemoryBuffer> InputBuffer)
+    : BaseRecords(new NaClBitcodeRecordList()) {
+  readNaClBitcodeRecordList(*BaseRecords, std::move(InputBuffer));
+}