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Postings from February 2006
"Joshua Isom" <loneowl@ritalin.shout.net> wrote: >I guess this is one place where being CISC really is better than being >RISC. But how much improvement with outputting to a pbc first? But a >couple notes, there's no --help-optimize like --help-debug, and as far as I >know, there's no way to disable optimizations completely, e.g. this pir > > .sub main :main > $N0 = pow 2.0, 5.0 > .end > > Is always converted to this. > > main: > set N0, 32 > end > I think that doesn't class as an optimization as such, but rather a way to avoid having to have opcodes that take two constant arguments. Over a number of instructions, that's a worthwhile saving. Ops cost space in the Parrot executable, which means we fit less of Parrot in the CPU caches, which is bad. > Which can lead to misleading test results for when pow's actually broken. > Hopefully we have tests with just one constant argument to detect breakage of this kind? It does bring out an interesting issue in so far as if we don't promise the same behaviour for pow then you could end up with a hybrid of the behaviour on the system the PBC was generated on and the system you run it on, but I think we're aiming for consistent behaviour. JonathanThread Previous