[cfe-dev] Announcing "clang-ctags"

[Douglas Gregor]

On Jul 26, 2012, at 2:11 AM, David Röthlisberger <david at rothlis.net> wrote:

> On 23 Jul 2012, at 22:54, Sean Silva wrote:
>> Ouch. This [running clang-ctags] is longer than compiling it!
> 
> Here's something I found quite interesting:
> 
> When I run clang-ctags over clang/lib/Analysis/AnalysisDeclContext.cpp
> it reports† that the call to clang_parseTranslationUnit takes 6.4s.
> 
> Giving the same compilation command directly to clang++ takes 1.4s.
> 
> This is a huge discrepancy, given that clang_parseTranslationUnit is
> only doing parsing, whereas clang++ is parsing *and* compiling! Even
> with -O3 clang++ only takes 1.6s. What can explain this?


Perhaps it's building a precompiled preamble, which is only worthwhile if you're going to reparse the same file many times. Try setting the environment variable LIBCLANG_TIMING=1 to see if anything odd shows up in the internal timing log; if not, please grab a profile!

	- Doug