On 8 August 2012 16:24, Ulrich Weigand <ulrich.weig...@de.ibm.com> wrote: > > Hello, > > I've had a look at the mp3player performance regressions (just with *some* > data sets) with the vector-alignment patch. Interestingly it turns out > that the patch basically does not change the generated code for the hot > spot (inv_mdct routine) at all. (The *only* change is which bits of the > incoming pointer the run-time alignment check generated by the vectorizer > tests for. But this has no practical consequences, since the check itself > is not hot, and the *decision* made by the check is the same anyway -- > everything is in fact properly aligned at runtime.) > > The other difference, outside of code, introduced by the vector-alignment > patch is that some global arrays used to be forcibly aligned to 16 bytes by > the vectorizer, and they are now only aligned to 8 bytes. To check whether > this makes a difference, I've modified the compiler as a hack to always > force all global arrays to be 16 byte aligned. And interestingly enough, > this appears to fix this particular performance regression ...
Are those arrays involved in any of the hot code? -- Mans Rullgard / mru _______________________________________________ linaro-toolchain mailing list linaro-toolchain@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-toolchain
