RE: [avr-gcc-list] code optimisation

[Dave Hansen]

From: Trevor White <address@hidden>

> Hi all.
>
> I am looking to find out how to write code that gcc prefers w.r.t. 
> optimisation. Where can I find out information on what gcc prefers to what 
> it does not?

Experimentation.

  while (!satisfied)
  {
     write_some_code();
     compile();
     examine_generated_code();
  }

Note that results may change with different versions of the same compiler...

However, C. A. R. Hoare said "Premature Optimization is the root of all 
evil."  D. Knuth agrred.  M. A. Jackson gave the following two rules for 
optimization:

1) Don't do it.
2) (For experts only) Don't do it yet.

My own rules (which aren't entirely orignal) are:

1) First make it right.
2) Then make it fast (or small).  But only if you _need_ to.
3) Selecting a better algorithm and/or data structure will produce more 
dramatic results than stupid coding tricks.

Regards,
  -=Dave

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