Fix a couple of self-assignments using memcpy.

[hintonda]

Summary

These two methods are essentially assignents, but don't check
for self-assignment and use memcpy for member variables.

Since they aren't actually operator=(), it's unclear what should be done:

• check and shortcut
• assert
• allow but s/memcpy/memmove/

[hintonda]

ping?

[clayborg]

First change looks good. Second one we can probably avoid doing anything in Value::AppendDataToHostBuffer and return 0. No need to copy data over itself.

source/Core/Value.cpp

145–146

Should probably return 0 if this == &rhs?

[hintonda]

• Address comments.

source/Core/RegisterValue.cpp

bool RegisterValue::SignExtend(uint32_t sign_bitpos) {
   case eTypeLongDouble:
   case eTypeBytes:
     break;
   }
   return false;
 }
 
 bool RegisterValue::CopyValue(const RegisterValue &rhs) {
+  if (this == &rhs)
+    return rhs.m_type == eTypeInvalid ? false : true;
+
   m_type = rhs.m_type;
   switch (m_type) {
   case eTypeInvalid:
     return false;
   case eTypeUInt8:
   case eTypeUInt16:
   case eTypeUInt32:
   case eTypeUInt64:

source/Core/Value.cpp

 
 Type *Value::GetType() {
   if (m_context_type == eContextTypeLLDBType)
     return static_cast<Type *>(m_context);
   return NULL;
 }
 
 size_t Value::AppendDataToHostBuffer(const Value &rhs) {
+  if (this == &rhs)
+    return 0;
+
   size_t curr_size = m_data_buffer.GetByteSize();
   Status error;
   switch (rhs.GetValueType()) {
   case eValueTypeScalar: {
     const size_t scalar_size = rhs.m_value.GetByteSize();
     if (scalar_size > 0) {
       const size_t new_size = curr_size + scalar_size;
       if (ResizeData(new_size) == new_size) {