Re: [Qemu-devel] [PATCH 0/6] target-arm: reduce usage of global env

[Blue Swirl <blauwirbel@gmail.com>]

On Wed, May 25, 2011 at 7:00 PM, Peter Maydell <peter.maydell@linaro.org> wrote:
> This patchset is largely aimed at rolling back the changes from an
> earlier patchset of mine:
> http://lists.gnu.org/archive/html/qemu-devel/2011-04/msg00244.html
> which made various Neon helper routines use the correct FP status
> flags by having them use the global env.
>
> Since we've decided we're trying to get rid of the global CPUState
> pointer (at least in C code), patches 1, 5, 6 here are basically
> reverting patches 1,2,3 of that earlier patchset. In order not
> to throw the baby out with the bathwater, patches 2, 3, 4 make
> the helper routines which need to use the FP status take a pointer
> to the fp status word. (In a few cases we can then merge them
> with the equivalent VFP helpers.)
>
> This obviously still leaves some global CPUState use in op_helper.c,
> but it's a move in the right direction.

Have you seen any measurable changes in performance? The discussion
about the performance effect of changes like this was not very
conclusive.