EGCS performance ?

[Joe Buck]

> Ok, I agree that Dhry. is a quasi-meaningless test, and as far as the
> topic of my posting is concerned, performance is only a component of
> the overall quality of compiler, however...
>  
>  RL> # GCC = egcs 1.1b                              781860.8
>  RL> # This is EGCS as of this morning.             829875.5
>  RL> # This is the SVR5 compiler from SCO.         1086956.5
>  RL> # This is Intel's Optimizing Compiler 2.1.4.  1582278.5
>  RL> # Same compiler without the i/p analysis.     1088139.2
> 
> ...I was surprised to see a large performance gulf (?) in such a
> simple test among EGCS and other "proprietary" compilers, and I'm
> wondering what is causing these gaps:

Some compiler vendors work very hard at optimizations specific for
Dhrystone, which isn't hard to do -- this is one reason why it's
such a misleading benchmark.  The gcc team, in the past, was opposed
to this kind of cheating so I believe that some patches designed to
specifically improve Dhrystone have been rejected.

> - embedded-auto-recognition of Drystone benchmark code... :-)

Well, the cheating isn't quite *that* blatant.  It's more that the
vendors choose transformations that will help their Dhrystone score
even if it doesn't help any other programs.