The Dart VM's AOT compiler has support for emitting binary size information for all the code that gets generated. This information can then be visualized.
Our AOT compiler accepts an extra --print-instructions-sizes-to=sizes.json
flag. If supplied the AOT compiler will emit binary size information for all generated functions to sizes.json
.
This flag can be passed to gen_snapshot
directly, or to the various wrapper scripts (e.g. pkg/vm/tool/precompiler2
):
% tools/build.py -mrelease -ax64 runtime_kernel dart_precompiled_runtime % pkg/vm/tool/precompiler2 --print-instructions-sizes-to=hello_sizes.json hello.dart hello.dart.aot
In Flutter, pass this argument to flutter build
:
% flutter build aot --release --extra-gen-snapshot-options=--print-instructions-sizes-to=hello_sizes.json
To visualize the information emitted by the AOT compiler one can use our binary size analysis tool:
% dart pkg/vm/bin/run_binary_size_analysis.dart hello_sizes.json hello_sizes Generated file:///.../sdk/hello_sizes/index.html % chrome hello_sizes/index.html
To visualize the differences between two AOT builds one can use our binary size comparison tool:
% dart pkg/vm/bin/compare_sizes.dart app-sizes--before.json app-sizes--after.json +---------+--------+--------------+ | Library | Method | Diff (Bytes) | +---------+--------+--------------+ ...
gen_snapshot also accepts an extra --write-v8-snapshot-profile-to=hello.heapsnapshot
flag. If supplied the AOT compiler will emit snapshot size information for all objects in the snapshot to hello.heapsnapshot
in V8 snapshot format.
This flag can be passed to gen_snapshot
directly, or to the various wrapper scripts (e.g. pkg/vm/tool/precompiler2
):
% tools/build.py -mrelease -ax64 runtime_kernel dart_precompiled_runtime % pkg/vm/tool/precompiler2 --write-v8-snapshot-profile-to=hello.heapsnapshot hello.dart hello.dart.aot
In Flutter, pass this argument to flutter build
:
% flutter build aot --release --extra-gen-snapshot-options=--write-v8-snapshot-profile-to=hello.heapsnapshot
This output can be visualized by loading it in the “Memory” tab in Chrome's developer tools, or by loading it into Graph Explorer.