Ryan Macnak
83eeab1e63
Change-Id: I9cc022443ba70b0a450a86943f7636dc6f8c975c Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/128373 Commit-Queue: Ryan Macnak <rmacnak@google.com> Reviewed-by: Ben Konyi <bkonyi@google.com>
2.4 KiB
AOT code size analysis
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.
Telling the AOT compiler to generate binary size information
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
Visualizing the information from the binary size json file
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
Comparing the sizes of two AOT builds
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) |
+---------+--------+--------------+
...
Object-level data
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.