Re: Why is GForth-ITC fast?

On Wed, 30 Apr 2008 19:30:05 -0700 (PDT), brian.fox@[EMAIL PROTECTED]
 wrote:

>I have been dis-assembling pieces of GForth and I don't understand why
>it is generally faster than other ITC Forths that are written in
>Assembler like CI-Forth or my old 16 bit HS/Forth.  The Assembler
>primitives seem to be so much smaller from what I can see.  Is the C
>compiler smarter than we are?

1) Instruction selection
2) Instruction scheduling

The performance coding rules for modern CPUs are not what you
would expect, because instructions are split into micro-ops.
PUSH and POP are particularly bad in many cases. See the Intel
and AMD optimisation manuals for the horribly gory details.

Stephen


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