[LLVMdev] speed and code size issues

Dale Johannesen dalej at apple.com
Fri Jul 17 17:46:20 PDT 2009


I'd look at  if_spppsubr.o, which is big in the llvm directories and  
doesn't appear in the gcc directory listings at all (I assume the  
listings were fed through tail or something, but there's clearly a  
sizeable difference there)

On Jul 17, 2009, at 5:41 PMPDT, Daniel Dunbar wrote:

> On Fri, Jul 17, 2009 at 5:12 PM, Jonathan Gray<jsg at goblin.cx> wrote:
>> On Fri, Jul 17, 2009 at 04:41:55PM -0700, Eli Friedman wrote:
>>> On Fri, Jul 17, 2009 at 4:14 PM, Jonathan Gray<jsg at goblin.cx> wrote:
>>>> This seems to go against notes such as
>>>> http://clang.llvm.org/features.html#performance
>>>> which claim clang is signifcantly faster than gcc.
>>>
>>> I think the URL you want is actually
>>> http://clang.llvm.org/performance.html.  The difference isn't as
>>> dramatic when you consider code generation, at least for the moment.
>>
>> Are these scripts to break down the time spent
>> in different stages available somewhere?
>
> Not currently, I've never bothered to make them public because they
> aren't very generic. They more or less amount to running the compiler
> with extra options like -fsyntax-only, or -E, and timing those. Its
> worth trying to reproduce the performance issue on a single file
> before going down this road. However, if you really want them I can
> ship you what I have, I just don't promise it will be very useful.
>
> - Daniel
>
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