Use metadata tokens instead of strings to find types and methods.
This makes the code to find methods more compact (a lot less strings in the
executable, and additionally in most cases a compact representation (32-bit
integer) of the corresponding metadata token and additional information can be
used, which results in less executable code (fewer parameters to methods,
etc)), resulting in smaller executables.
Size savings are around 200kb for dont link apps, and 20-60kb for linked apps
(this obviously varies a lot depending on how much has to registered by the
registrar).
| | Before | After | Diff |
|----------------|--------------:|--------------:|------------------:|
| dontlink/32bit | 102.810.144 | 102.609.456 | -200.688 = -0,20% |
| dontlink/64bit | 107.420.576 | 107.221.792 | -198.784 = -0,19% |
| linksdk/32bit | 40.957.296 | 40.936.864 | -20.432 = -0,05% |
| linksdk/64bit | 43.113.136 | 43.093.936 | -19.200 = -0,04% |
| linkall/32bit | 38.410.032 | 38.348.288 | -61.744 = -0,16% |
| linkall/64bit | 40.315.200 | 40.267.344 | -47.856 = -0,12% |
Additionally I've removed the `lazy_map` dictionary, which we populated at
startup and was used to map between Class instances and the corresponding
managed type's FullName, and instead iterate over a native array of Class ->
metadata token mappings whenever we need to look up the managed type for a
certain Class instance.
This is slightly slower for each type we need to look up (for a non-linked app
there might be a 2000-3000 entries in the native array, which would be
iterated instead of using a hashtable lookup), but it's only done once per
type and there's a significant startup memory improvement.
For a non-linked test app I get the following using the Xamarin profiler:
| | Before | After | Diff |
|-------------------|--------:|--------:|----------------:|
| Memory allocated | 2,8 MB | 2,4 MB | -0,4 MB = -14 % |
| Objects allocated | 43678 | 38463 | -5215 = -12 % |
| Private bytes | 26,6 MB | 24,4 MB | -2,2 MB = -8,3% |
| Working set | 26,6 MB | 24,4 MB | -2,2 MB = -8,3% |
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