Fix MCDataAtom never calling remap when adding data.

This patch fixes a small mistake in MCDataAtom::addData() where it doesn't ever
call remap():

-  if (Data.size() > Begin - End - 1)
+  if (Data.size() > End + 1 - Begin)
     remap(Begin, End + 1);

This is currently not visible because of another bug is the disassembler, so
the patch includes a unit test.

Patch by Stephen Checkoway.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192823 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/unittests/MC/MCAtomTest.cpp b/unittests/MC/MCAtomTest.cpp
new file mode 100644
index 0000000..17b056c
--- /dev/null
+++ b/unittests/MC/MCAtomTest.cpp
@@ -0,0 +1,31 @@
+//===- llvm/unittest/MC/MCAtomTest.cpp - Instructions unit tests ----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/MC/MCAtom.h"
+#include "llvm/MC/MCModule.h"
+#include "gtest/gtest.h"
+
+namespace llvm {
+namespace {
+
+TEST(MCAtomTest, MCDataSize) {
+  MCModule M;
+  MCDataAtom *Atom = M.createDataAtom(0, 0);
+  EXPECT_EQ(uint64_t(0), Atom->getEndAddr());
+  Atom->addData(0);
+  EXPECT_EQ(uint64_t(0), Atom->getEndAddr());
+  Atom->addData(1);
+  EXPECT_EQ(uint64_t(1), Atom->getEndAddr());
+  Atom->addData(2);
+  EXPECT_EQ(uint64_t(2), Atom->getEndAddr());
+  EXPECT_EQ(size_t(3), Atom->getData().size());
+}
+
+}  // end anonymous namespace
+}  // end namespace llvm