IRC logs for #openrisc Sunday, 2012-03-25

jonibo|laptopwhat would be the consequence of making r0 just another register... i.e. not constant zero at all... when you need a 0 zero register, you can just use any register really...17:37
jonibo|laptopwhat's the concrete advantage of a constant zero register?17:38
derRicharddanm, i forgot to resend you the r0-patch :-\17:45
derRichardAFAIK a zero register is useful because you don't need to write 0 to it all the time...17:45
derRichardmips has also such an register17:46
jonibo|laptopyeah, I can see that argument... but what the uses of a register that is known to contain 0... seems a lot of operations can be optimized better if you already know that one of the operands is 017:48
derRichardi really don't know. i'm a pure software guy :)17:48
jonibo|laptopx && r0 = 0, might as well just load 0 to the result register17:48
jonibo|laptopx OR r0 = x, might as well just load x to the result reg17:49
jonibo|laptopSPR accesses use r0 a lot... but seems a small cost to load r0 with 0 as needed17:49
juliusbwell it's probably the same argument for having 1, 2 or 0xffffffff preloaded in a register18:29
stekernwell, or1k being a 3-register instruction set, you kind of need the r0 to load the x into result reg22:51
stekernnever mind that, you don't....22:53

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