llvm dev - Sep 2009 - [LLVMdev] FYI: Phoronix GCC vs. LLVM-GCC benchmarks

On Wed, Sep 16, 2009 at 10:52 AM, Eric Christopher <echristo at apple.com>
wrote:
> On Sep 16, 2009, at 10:36 AM, Daniel Dunbar wrote:
>> Since we are in the area, what *should* O1 do?
>>
>> It's basically good for nothing, since it doesn't tune for size
or
>> performance. The only good I personally ever have for it is once in a
>> while there is a miscompile at -O1 which narrows the problem.
>>
>> Would it be crazy to make -O1 equivalent to -Os?
>
> I've always used O1 for a quick cleanup so that my debug code
doesn't
> completely suck, but hasn't been optimized into oblivion for gdb.  Also
> makes looking at the resultant assembly dumps fairly easy.
If this is from the compiler programmer perspective, we have better
tools for that. If this is from the user perspective, currently they
all are bad with LLVM for the former, and we should similarly fix all
of them. :)
> But yes, that'd be crazy :)
Was that a -1 on doing it, though? :)

 - Daniel

>>
>> I've always used O1 for a quick cleanup so that my debug code
doesn't
>> completely suck, but hasn't been optimized into oblivion for gdb.
>> Also
>> makes looking at the resultant assembly dumps fairly easy.
>
> If this is from the compiler programmer perspective, we have better
> tools for that. If this is from the user perspective, currently they
> all are bad with LLVM for the former, and we should similarly fix all
> of them. :)
>
Well, it's mostly for both :)
>> But yes, that'd be crazy :)
>
> Was that a -1 on doing it, though? :)
Don't see much of a reason to be incompatible with gcc on this one.  
Maybe a new set of command line options for optimization? But what do  
I know?

*shrug* I've always hated dealing with command line options :)

-eric

On Sun, Sep 20, 2009 at 12:47 PM, Eric Christopher <echristo at apple.com>
wrote:
>>>
>>> I've always used O1 for a quick cleanup so that my debug code
doesn't
>>> completely suck, but hasn't been optimized into oblivion for
gdb.  Also
>>> makes looking at the resultant assembly dumps fairly easy.
>>
>> If this is from the compiler programmer perspective, we have better
>> tools for that. If this is from the user perspective, currently they
>> all are bad with LLVM for the former, and we should similarly fix all
>> of them. :)
>>
>
> Well, it's mostly for both :)
>
>>> But yes, that'd be crazy :)
>>
>> Was that a -1 on doing it, though? :)
>
> Don't see much of a reason to be incompatible with gcc on this one.
Note that this comment doesn't really make sense. The set of
optimizations which runs for -O1 and -Os aren't at all "gcc
compatible", changing the list of what runs at -O1 doesn't make
llvm-gcc/clang any more or less "compatible". Given that we are free
to change the passes that run at -O1, I'm just suggesting we change it
enough that it coincides with -Os. :)

 - Daniel
> Maybe a
> new set of command line options for optimization? But what do I know?
>
> *shrug* I've always hated dealing with command line options :)
>
> -eric
>
>