Now, when writing an AOT snapshot in bare instructions mode, only
the actual instructions in the RawInstructions payload are serialized
instead of the entire RawInstructions object.
Since there are no longer RawInstructions objects in these AOT
snapshots, we also change how Code objects are serialized. Instead
of just containing a reference to the RawInstructions object, we
serialize two pieces of information: where the instructions
payload for this Code object begins and whether there was a single
entry for the instructions payload. (To save space, the single
entry bit is serialized as the low order bit of the unchecked
offset, which was already being serialized).
While we also need the length of the instructions payload, we
approximate it for all but the last Code object by subtracting
the next Code object's payload start from this Code object's
payload start. For the last Code object, we assume it extends
to the end of the instructions image.
Changes on flutter gallery in release mode:
armv7: instructions size -2.70%, total size -1.73%
armv8: instructions size -6.04%, total size -3.63%
Fixes https://github.com/dart-lang/sdk/issues/38451.
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-linux-release-x64-try,vm-kernel-precomp-linux-release-simarm-try,vm-kernel-precomp-linux-release-simarm64-try,vm-kernel-precomp-linux-release-simarm_x64-try,vm-kernel-precomp-android-release-arm64-try,vm-kernel-precomp-android-release-arm_x64-try,vm-kernel-precomp-mac-release-simarm64-try,vm-kernel-precomp-win-release-x64-try
Change-Id: Ia0a5c4e5e47c956776dc62503da38ec55a143c04
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/134325
Commit-Queue: Teagan Strickland <sstrickl@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Teagan Strickland
e01457d138