MC CFG: Remap enough for the inserted instruction.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188873 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCAtom.cpp b/lib/MC/MCAtom.cpp
index 2626b39..f3ea6c3 100644
--- a/lib/MC/MCAtom.cpp
+++ b/lib/MC/MCAtom.cpp
@@ -72,8 +72,8 @@
 // MCTextAtom
 
 void MCTextAtom::addInst(const MCInst &I, uint64_t Size) {
-  if (NextInstAddress > End)
-    remap(Begin, NextInstAddress);
+  if (NextInstAddress + Size - 1 > End)
+    remap(Begin, NextInstAddress + Size - 1);
   Insts.push_back(MCDecodedInst(I, NextInstAddress, Size));
   NextInstAddress += Size;
 }