[PR lto/41528] Add internal documentation in doc/lto.texi

[Michael Matz]

Hi,

On Mon, 15 Nov 2010, Diego Novillo wrote:

> > cc1, cc1plus, f951, and lto1 -- where does '1' here mean? It always 
> > got me thinking where cc2/lto2/... is.
> 
> Lost in the mists of tradition.  IIRC, the '1' used to distinguish it 
> from 'cc', the driver (others may remember the true reason, I'm too 
> young ;).  We are creatures of habit.

The early C compilers, including the Portable C Compiler were multi-pass 
compilers, consisting of executables 'pass1' and 'pass2' (plus the 
preprocessor), communicating via text files.  Later versions had the 
option of producing just one binary, when the machines had more memory.  I 
guess RMS left open the option of also having a second super pass that 
he'd then have called cc2.

Perhaps we should call lto1 cc2?  ;-)


Ciao,
Michael.
P.S: The old document "A Tour Through the Portable C Compiler" is a nice 
read on these topics: 
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.48.3512