Report failure if there are less bytes than requested in a MemoryObject.

Before we just left the remaining bytes uninitialized. This is another step in making llvm valgrind-clean again.

llvm-svn: 138705

llvm/lib/Support/MemoryObject.cpp

@@ -19,8 +19,11 @@ int MemoryObject::readBytes(uint64_t address,
                             uint64_t* copied) const {
   uint64_t current = address;
   uint64_t limit = getBase() + getExtent();
-  
-  while (current - address < size && current < limit) {
+
+  if (current + size > limit)
+    return -1;
+
+  while (current - address < size) {
     if (readByte(current, &buf[(current - address)]))
       return -1;