[llvm-commits] [PATCH] Make Path::GetMainExecutable faster on OSX

[Chris Lattner]

On Sep 8, 2009, at 2:58 PM, Daniel Dunbar wrote:

> Wow, nice catch -- I've known something was wrong because of the
> amount of system time it consumes, but hadn't dug in. This makes your
> patch an even bigger win w/ more threads, its almost 50% faster for
> me.
>
> Looking at the code now I'm wondering if it is even right that
> clang-cc uses the main executable path to resolve headers. I think
> this change got made to accommodate symlinked binaries, but I'm not
> sure that "GetMainExecutablePath" is really the right way to find
> this. Chris?

I don't really know either.  Nick, do you have an opinion about this?

-Chris

>
> - Daniel
>
> On Tue, Sep 8, 2009 at 11:52 AM, Benjamin
> Kramer<benny.kra at googlemail.com> wrote:
>> Playing around with shark shows that much of the startup time of  
>> clang-cc is
>> spent in dladdr looking for the executable path. There is another  
>> dyld API
>> called _NSGetExecutablePath which does the same thing much faster.  
>> The
>> function is available since 10.2 and documented in "man 3 dyld" (I  
>> don't
>> know why it has a leading underscore though).
>>
>> benchmark: clang testsuite on my 2007 macbook pro (debug build,  
>> best of 3
>> runs)
>>
>> dladdr:
>> --- Running clang tests for i686-apple-darwin10.0.0 ---
>> Testing Time: 57.76s
>>
>> _NSGetExecutablePath:
>> --- Running clang tests for i686-apple-darwin10.0.0 ---
>> Testing Time: 48.71s
>>
>>
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