Re: [TUHS] History of popularity of C

[Larry McVoy <lm@mcvoy.com>]

On Fri, May 22, 2020 at 11:40:11AM -0700, John Gilmore wrote:
> Tyler Adams <coppero1237@gmail.com> wrote:
> > Doesn't C++ also generate tight code and is fairly close to the metal?
> > Today C++ is the high performant language for game developers and HFT shops.
> > 
> > But, I never found it on any of these embedded systems, it was straight C.
> 
> My take on this is that programmers who understand the underlying
> hardware architecture can easily intuit the code that would result from
> what they write in C.  There are only a few late features (e.g. struct
> parameters, longjmp) that require complex code to be generated, or
> function calls to occur where no function call was written by the
> programmer.

Amen.

> Whereas in C++, Pascal, Python, APL, etc, a few characters can cause the
> generated code to do immense amounts of unexpected work.  Think of
> string compares, hash table types, object initializers, or arbitrary
> amounts of jumping through tables of pointers to different kinds of
> objects.  Automated memory allocation.  Garbage collection.

Double amen.

> This is both a blessing and a curse.  In C it was quite predictable how
> well or badly typical sections of your code would perform.  If the
> performance was bad, it was YOUR fault!  But at least YOU could fix it,
> without learning to hack a compiler instead of your own application.

Triple amen.

> (I once found Berkeley SPICE code doing string compares in a triply
> nested loop, just to look up the names of the signals.  In C.  Making
> changes to a large state machine going into a custom chip was taking the
> Sun hardware engineers multiple hours per change.  I spent weeks finding
> the source code (Sun's tools group was dysfunctional; I got it from
> UCB).  In half a day of profiling it and fixing it to cache the
> result of the first string lookup on each signal name, four hour
> rebuilds went down to under a minute.  A second day of profiling
> and cacheing, just for fun, took it down to 10 seconds.)

Gazillion amens (I especially loved the jab at Sun's tools group, I
wrote the SCM that Sun used for Solaris initially.  They tried to get
me to join the tools group to make my stuff "official" - it worked just
fine being "unofficial".  I took a look at the people in the tools group,
no offense, but it was a big step down from working with people like srk
and gingell and shannon, not to mention that all of my peers were smart.
Tools group, just say no.)