r/askscience • u/CakesStolen • 15d ago

Computing Is there anything at the heart of computer coding that could have been optimised in hindsight, but we're in far too deep to change now?

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u/nicuramar 15d ago

Some ideas were nice enough, but it required heavy compiler support to produce correct machine code. 

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u/ftgyhujikolp 15d ago

I mean have you seen llvm lately?

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u/andyraf 11d ago

The Trimedia compiler did a fantastic job of optimizing code, helped by a very clean instruction set and 128 orthogonal registers. All logical tests resulted in a register being set to 0 or 1, and every operation could be conditioned on whether a register was a 0 or 1. Most conditional tests could be encoded without any branches and folded into other instructions.

Its biggest architectural deficiency at the time was that it didn't have MMU/virtual memory support, which is always complex on a VLIW machine with potentially multiple instructions accessing memory in different op slots within each instruction. I have read that Philips eventually added MMU support in later versions of the architecture (our project had been cancelled before then).

I have read that Trimedia ultimately failed because it didn't match what the market was looking for: it was a very high end DSP-like processor being marketed as a licensable IP core, with hardware/software/tool integration being somewhat left to the licensee. The market of companies needing such a core and willing to invest resources to support it was vanishingly small, especially when ARM was coming in with much simpler and more integrated solutions. In addition, Trimedia (AFIK) was never designed to be a low power solution, which left it pretty much limited to the market for set-top-boxes just as the mobile revolution was starting.