This reduces small tagged integers on 64 bit platforms from 63 bits to
31 bits plus one tag bit.
This is a step on the way to compile-time-optional compressed pointers
on 64 bit platforms. See more about this at go/dartvmlearnings
This causes a slowdown for some uses of integers that don't fit in 31
signed bits, but because both x64 and ARM64 have unboxed 64 bit
integers now the performance hit should not be too bad.
This reapplies the change reviewed at
https://dart-review.googlesource.com/c/sdk/+/46244R=kustermann@google.com
Change-Id: I605c21506ec7d4c69fa7049bc419b3ee370685fc
Reviewed-on: https://dart-review.googlesource.com/50202
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Erik Corry <erikcorry@google.com>
Erik Corry
0e9a77a360