System programming in D (Was: The God Language)

[Walter Bright]

On 12/30/2011 10:31 AM, Chad J wrote:
> As an aside, I think that people want forced inlining because it gives
> them another tool to tweak with.  My experiences with optimization tend
> to suggest I can usually optimize things really well with a few short
> cycles of profile->experiment->profile.  I don't think I've ever really
> /needed/ to dive into assembly yet.  My ventures into the assembler have
> been either purely recreational or academic in nature.  Now, something
> like an inline feature can help a lot with the "experiment" part of the
> cycle.  It's just another knob to twist and see if it gives the result
> you want.  Portability be damned, if it gets the thing out the door, I'm
> using it!  But, I kind of hate that attitude.  So it's much more
> comforting to be able to twist that knob without sacrificing portability
> too.  I wouldn't expect it to run as fast on other compilers; I /would/
> expect it to compile and run correctly on other compilers.  And if
> enregistering variables is more important, then we might want to have a
> way to enregister variables too.

Back in the olden days, I provided a detailed list of optimizer switches that 
turned on/off all sorts of optimizations. In the end it turned out that all 
people wanted was an "optimize" switch which is why dmd has only -O.

The reason dmd has a -inline switch is because it's hard to debug code that has 
been inlined.

The reason C's "register" keyword went away was because:

1. the variables after optimization transformations may be very different than 
before

2. programmers stunk at picking the right variables for registers

3. even if (2) was done right, as soon as the first code maintainer dinked with 
it, they never bothered to go fix the register declarations

4. optimizers got pretty good at automatic register allocation

5. there's nothing portable about enregistering, even with a portable syntax

6. the register keyword offered no way to hint which variables were more 
important to enregister than others