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From: Julian S. <js...@ac...> - 2012-09-08 22:22:16
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> > find out is to implement it. :-) I'll dig around for a testcase > > that exhibits the behavior you describe above so I can measure any > > improvement gained with the additional cached rounding mode. > > It might be much less work to simply change the code :) > I have mostly given up myself on measuring the win of micro > optimizations. If there is a good argument in favour I go ahead > and implement it. I just measure that runtime does not get worse. This is one of those things that has no effect for 99.99% of cases but may have a big impact for the cases it hits. I suspect it would be easy to write a test case that shows it -- a single basic block that contains a lot of both kinds of instructions, iterated over a lot, with suitable rounding mode setup beforehand. The tricky bit is to ensure it is right. If you do add something, pls can there be a testcase for it too? J |