[PATCH] Remove copies of MCSubtargetInfo from MCRelaxableFragment

[Rafael Espíndola]

Patch 1 LGTM.


On 8 July 2015 at 20:30, Duncan P. N. Exon Smith <dexonsmith at apple.com> wrote:
> Last I checked my `-g -flto` workload, `MCRelaxableFragment` was taking
> up 4.7% of the heap during LTO.  Since these aren't debug info related,
> the relative cost is even higher without `-g` (I figure 10% or so?).
> The struct layout contained a shock: over half of
> `sizeof(MCRelaxableFragment)` comes from a local copy (!?) of
> `MCSubtargetInfo`.
>
> It was more roundabout than I expected to fix, but this patch series
> does it.  0001 removes the copy of `MCSchedModel` from
> `MCSubtargetInfo`, 0002-0004 change the `MCSubtargetInfo` API to prove
> that only the feature bits get mutated, and 0005 moves the copies of
> `MCSubtargetInfo` to a cache in `MCContext`.
>
> I'd love a pre-commit sanity check from someone for two of these:
>   - 0001 (the object for `MCSchedModel::GetDefaultMCSubtarget()` doesn't
>     need to be defined in the header for some reason, does it?) and
>   - 0003 (I'm touching *all* the targets...)
>
> and I've provided the rest of the series (and a combined all.patch) for
> context.
>
>