[cfe-dev] Smart pointer usage in the Parser/Actions

[steve naroff]

Folks,

Over the past week or so, there's been some discussion about making  
extensive use of smart pointers in the parser (on clang-dev).

Since the change is pervasive (and influences the programming model),  
we discussed the topic yesterday (with Apple compiler engineers  
working on clang).

We concluded it makes sense to follow-through with the changes. Our  
only concern is performance: we don't want to degrade performance of  
parsing correct code. For example, parsing system headers remains a  
bottleneck. Since system headers don't contain invalid code, it's  
important this improvement not degrade performance. Once the change is  
complete, it's important we do "A/B comparisons" to measure the  
performance for parsing valid code.

Once we have the data, we can decide if the cost is worth the benefit.  
We don't anticipate a major slowdown, however given the scope of the  
change (and frequency of calling "move"), it's something we need to  
verify.

We'd like to thank Sebastian for tackling this project!

snaroff