GCC 8 vs. GCC 9 speed and size comparison

[Martin Liška]

On 4/15/19 5:07 PM, Michael Matz wrote:
> Hi,
> 
> On Mon, 15 Apr 2019, Jakub Jelinek wrote:
> 
>>> It seems the C++ parser got quite a bit slower with gcc 9 :-( Most 
>>> visible in the compile time for tramp-3d (24%) and kdecore.cc (18% 
>>> slower with just PGO); it seems that the other .ii files are C-like 
>>> enough to not
>>
>> Is that with the same libstdc++ headers (i.e. identical *.ii files) or 
>> with the corresponding libstdc++ headers?  Those do change a lot every 
>> release as well.
> 
> The tramp3d and kdecore testcases are preprocessed files from a 
> collection of benchmark sources we use, i.e. the same 
> input for all compilers.  I think the {gimple,generic}-match.ii are in the 
> same league.

Yes, except kdecore.cc I used in all cases .ii pre-processed files. I'm going
to start using kdecore.ii as well.

As Honza pointed out in the email that hasn't reached this mailing list
due to file size, there's a significant change in inline-unit-growth. The param
has changed from 20 to 40 for GCC 9. Using --param inline-unit-growth=20 for all
benchmarks, I see green numbres for GCC 9!

Martin

> 
> 
> Ciao,
> Michael.
> 

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