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Re: comments on loop changes
Richard Henderson writes:
> On Sun, Feb 14, 1999 at 09:25:40PM +1300, Michael Hayes wrote:
> > The following hack makes all the difference for me. With this, all my
> > test routines generate good code. Maybe the test should be more
> > selective but I'm only tinkering and do not understand the heuristics
> > employed by GIV combination.
>
> The problem is that on all machines I have regular contact with,
> all addressing modes cost the same execution-wise. So to avoid
> bad code on those machines, some artificial costing would have
> to be added just for the benefit of loop. Which seems too gross
> for words.
Is this cost in terms of execution time, number of bits required to
encode the addressing mode within the opcode, or both?
In any case, if these machines have the same cost for all addressing
modes, my tweak to the cost will have no effect. Or are you also
observing bad behaviour on these machines?
Michael.