Re: detailed comparison of generated code size for GCC and other compilers

[John Regehr <regehr@cs.utah.edu>]

> I wonder if the original program was already broken or was this
> something your conversion introduced?

Not sure about this specific case but I'm sure there's some of each.

I also noticed these testcases but decided to leave them in for now. 
Obviously the code is useless, but it can still be interpreted according 
to the C standard, and code can be generated.  Once you start going down 
the road of exploiting undefined behavior to create better code -- and gcc 
already does this pretty aggressively -- why not keep going?

That said, if there's a clear sentiment that this kind of test case is 
undesirable, I'll make an effort to get rid of these for subsequent runs. 
The bottom line is that these results are supposed to provide you folks 
with useful directions for improvement.

> Looking further down the table a lot of the differences on 
> empty-after-optimization functions (lots of 5 vs 2 bytes) seem to be 
> that gcc-head uses frame pointers and the other compiler doesn't. 
> Clearly for a fair comparison these settings should be the same.

I wanted to avoid playing flag games and go with -Os (or nearest 
equivalent) for all compilers.  Maybe that isn't right.

John Regehr