[cfe-dev] types and efficiency

[Douglas Gregor]

On Feb 17, 2011, at 3:07 AM, Zach Anderson wrote:
> I notice in the definition of QualType, and the representation of types 
> in general, that a lot of attention is paid to minimizing memory 
> consumption. I was thinking of adding some information to types, but I 
> don't want to upset any efficiency gains from these optimizations.

It's often possible to add information into the type system without making the data structures much larger.

> My question is: are there any performance tests in the test suite that 
> would be able to measure the impact of these changes?


There aren't any specific performance tests for the type subsystem. We tend to take a large preprocessed file (say, the contents of Cocoa.h on Mac OS X) and time parsing with -fsyntax-only to determine the effects of changes.
	- Doug