On Tue, 15 Feb 2000, you wrote:
> 686 optimized binaries would take up less space -- libraries
>would be smaller -- fewer instructions to accomplish the same task. The
>analogy with energy is flawed. We are talking space. Space can be
>conserved using more efficient instructions to accomplish the same
>task -- like going from the 8085 to the 8086,
>the heart of a string move went down to 1 instruction with a prefix.
>Previously you'd have to maintain a counter, mov mem ->reg, mov reg->mem,
>increment pointers, do a compare and conditional jmp.
The heart of a string move went down to 1 instruction with a prefix... But
around the time of the '486, it became faster to roll your own loops instead of
using LOOP, and to avoid using the string instructions except for MOVS.
A lot of the compiler optimisations are probably geared towards generating a
more optimal instruction mix for a certain processor, not just taking advantage
of new instructions.
My gcc doesn't seem to support pentium optimisations, but compiling a small
test program for a 486 versus 386 increased the size slightly. Are you sure
686 optimized binaries get smaller?
TTFN
Andy
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