Re: [Chicken-hackers] Why isn't OPTIMIZE_FOR_SPEED the default?

[Felix Winkelmann]

From: John Cowan <address@hidden>
Subject: Re: [Chicken-hackers] Why isn't OPTIMIZE_FOR_SPEED the default?
Date: Sun, 2 Nov 2014 17:38:39 -0500

> Peter Bex scripsit:
> 
>> Am I going completely mad and am I missing something obvious?  Is there
>> a good reason why optimizing for speed isn't the default?  
> 
> It's no more than a guess, but historically -O2 and -O3 tickled bugs that
> didn't appear at -O1.  Probably someone (Felix?) fell over such a bug
> long ago, removed the -On argument, saw the bug go away, and left it
> at that.  Ghu knows chicken's output is a torture test for C compilers.

That's indeed the case. -O3 is not always reliable and can trigger
C-compiler bugs, depending on the exact make and version. I remember
encountering at least one, some time ago. The produced C code is
actually not that stressful (as compared to say, Gambit, which can
produce huge C functions, which make register-allocation a tough job
for the compiler). Nevertheless, the code produced by CHICKEN is not
what C compilers usually see.


felix