[Libre-soc-bugs] [Bug 1155] O(n^2) multiplication REMAP mode(s)

[bugzilla-daemon at libre-soc.org]

https://bugs.libre-soc.org/show_bug.cgi?id=1155

--- Comment #45 from Luke Kenneth Casson Leighton <lkcl at lkcl.net> ---
(In reply to Jacob Lifshay from comment #41)

> software will care about, but are practically required for correctness --
> the temporaries.

too complex to discuss and completely out of scope for this bugreport.
the focus of this bugreport, 1155, is the svshape3 and svshape4
instructions, when we are under time pressure and a limited budget.

shelve it please.

> if the cpu has to look 3000 instructions into the future to see that the
> temporary is ultimately overwritten,

if you're looking 3,000 instructions into the future then you already
have a massively-optimised CPU and are loooong into "low-hanging fruit".
5% or above you pay attention to, first. 0.33% is just not worth
bothering with vs the cost.

drop it please: mentally do the cost-benefit analysis ok?

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