[cfe-commits] r99912 - in /cfe/trunk: include/clang/AST/DeclBase.h include/clang/AST/DeclCXX.h include/clang/AST/DeclFriend.h include/clang/AST/DeclObjC.h include/clang/AST/DeclTemplate.h include/clang/AST/Expr.h include/clang/AST/ExprCXX.h include/clang/AST/ExprObjC.h include/clang/AST/Statistics.h include/clang/AST/Stmt.h include/clang/AST/StmtCXX.h include/clang/AST/StmtObjC.h include/clang/AST/Type.h lib/AST/DeclBase.cpp lib/AST/Expr.cpp lib/AST/Stmt.cpp lib/AST/Type.cpp

[Douglas Gregor]

On Mar 30, 2010, at 1:54 PM, Chris Lattner wrote:

> 
> On Mar 30, 2010, at 1:41 PM, Douglas Gregor wrote:
> 
>>>> 
>>>> The statistics are only gathered when NDEBUG is not defined, since
>>>> they introduce potentially-expensive operations into very low-level
>>>> routines (isa).
>>> 
>>> Interesting, are these checks (without the instrumentation) expensive and worth optimizing?  What do these metrics tell us?
>> 
>> Not as much as I'd hoped. Turning all of these checks into a constant "false" (in effect, partly specializing Clang for C code) only yielded a 2.8% performance improvement in -fsyntax-only on some sample C code, so these checks aren't all that expensive.
> 
> Ok, is it worth keeping this code?

No. 

	- Doug