ProfileData: Introduce the InstrProfReader interface and a text reader

This introduces the ProfileData library and updates llvm-profdata to
use this library for reading profiles. InstrProfReader is an abstract
base class that will be subclassed for both the raw instrprof data
from compiler-rt and the efficient instrprof format that will be used
for PGO.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204482 91177308-0d34-0410-b5e6-96231b3b80d8

lib/ProfileData/InstrProfReader.cpp

@@ -0,0 +1,84 @@
+//=-- InstrProfReader.cpp - Instrumented profiling reader -------------------=//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains support for reading profiling data for clang's
+// instrumentation based PGO and coverage.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ProfileData/InstrProfReader.h"
+#include "llvm/ProfileData/InstrProf.h"
+#include "llvm/Support/Endian.h"
+
+#include <cassert>
+
+using namespace llvm;
+
+error_code InstrProfReader::create(std::string Path,
+                                   std::unique_ptr<InstrProfReader> &Result) {
+  std::unique_ptr<MemoryBuffer> Buffer;
+  if (error_code EC = MemoryBuffer::getFileOrSTDIN(Path, Buffer))
+    return EC;
+
+  // Sanity check the file.
+  if (Buffer->getBufferSize() > std::numeric_limits<unsigned>::max())
+    return instrprof_error::too_large;
+
+  // FIXME: This needs to determine which format the file is and construct the
+  // correct subclass.
+  Result.reset(new TextInstrProfReader(Buffer));
+
+  return instrprof_error::success;
+}
+
+void InstrProfIterator::Increment() {
+  if (Reader->readNextRecord(Record))
+    *this = InstrProfIterator();
+}
+
+error_code TextInstrProfReader::readNextRecord(InstrProfRecord &Record) {
+  // Skip empty lines.
+  while (!Line.is_at_end() && Line->empty())
+    ++Line;
+  // If we hit EOF while looking for a name, we're done.
+  if (Line.is_at_end())
+    return error(instrprof_error::eof);
+
+  // Read the function name.
+  Record.Name = *Line++;
+
+  // Read the function hash.
+  if (Line.is_at_end())
+    return error(instrprof_error::truncated);
+  if ((Line++)->getAsInteger(10, Record.Hash))
+    return error(instrprof_error::malformed);
+
+  // Read the number of counters.
+  uint64_t NumCounters;
+  if (Line.is_at_end())
+    return error(instrprof_error::truncated);
+  if ((Line++)->getAsInteger(10, NumCounters))
+    return error(instrprof_error::malformed);
+
+  // Read each counter and fill our internal storage with the values.
+  Counts.clear();
+  Counts.reserve(NumCounters);
+  for (uint64_t I = 0; I < NumCounters; ++I) {
+    if (Line.is_at_end())
+      return error(instrprof_error::truncated);
+    uint64_t Count;
+    if ((Line++)->getAsInteger(10, Count))
+      return error(instrprof_error::malformed);
+    Counts.push_back(Count);
+  }
+  // Give the record a reference to our internal counter storage.
+  Record.Counts = Counts;
+
+  return success();
+}