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I'm not actually sure how they had their spreadsheets set up, probably had a bunch of conditional formatting setup to highlight pipeline hazards, along with formulas to show total and wasted cycles counts.

Both Architectures had exposed pipelines, meaning the result of an operation would take a few cycles to show up in the destination register and some operations would take longer than others. You might have to insert a bunch of NOPs to make sure the data would be ready for the next instruction that needed it. Both Architectures were also dual issue, meaning two completely independent operations, operating on completely independent registers would be manually packed into a single instruction by the programmer. There also would be restrictions on which types of instructions could go in each half of the instruction, if you didn't have an instruction, you have to put a NOP there.

I'm pretty sure Sony liked the spreadsheets because it forced the programmer to see where all the NOPs were. The programmer would be expected to refactor things and manually unroll loops until all the NOPs were filled with useful instructions and peak performance was reached.




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