Vyacheslav Egorov
13d27d669d
This change bakes binary search table which maps PC ranges to corresponding stack maps and Code objects (if still present in the snapshot) into RO data section of the snapshot - instead of constructing it at load time. This allows to considerably reduce amount of work done when loading Code cluster for programs which have majority of their Code objects discarded (i.e. in DWARF stack traces mode): as we no longer write / read any information for discarded Code objects. This CL also changes program visitor to deduplicate Code objects if their instructions are deduplicated in AOT mode. Only a single Code object can be choose as a representative for the given PC range so it does not make sense to write multiple Code objects into the snapshot which refer to the same Instructions. The overall improvement is hard to quantify but ReadProgramSnapshot shows the following improvement when starting a large Flutter application on a slow Android device: before 223.55±59.94 (192.02 .. 391.74) ms after 178.06±47.03 (151.31 .. 291.34) ms This CL packs CompressedStackMaps next to the binary search table itself allowing us to address them via offsets instead of pointers. Snapshot sizes are actually affected positively by this change. On the same large Flutter application I see DWARF stack traces on: -1.34% total SO size DWARF stack traces off: -1.63% total SO size Issue https://github.com/dart-lang/sdk/issues/46116 TEST=ci Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-dwarf-linux-product-x64-try,vm-kernel-precomp-linux-debug-simarm64c-try,vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-linux-debug-x64c-try,vm-kernel-precomp-linux-product-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-linux-release-x64-try Change-Id: Ic997045a33daa81ec68df462a0792915885df66b Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/220766 Reviewed-by: Alexander Markov <alexmarkov@google.com> Reviewed-by: Martin Kustermann <kustermann@google.com> Commit-Queue: Slava Egorov <vegorov@google.com>
Dart
A client-optimized language for fast apps on any platform
Dart is:
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Optimized for UI: Develop with a programming language specialized around the needs of user interface creation.
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Productive: Make changes iteratively: use hot reload to see the result instantly in your running app.
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Fast on all platforms: Compile to ARM & x64 machine code for mobile, desktop, and backend. Or compile to JavaScript for the web.
Dart's flexible compiler technology lets you run Dart code in different ways, depending on your target platform and goals:
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Dart Native: For programs targeting devices (mobile, desktop, server, and more), Dart Native includes both a Dart VM with JIT (just-in-time) compilation and an AOT (ahead-of-time) compiler for producing machine code.
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Dart Web: For programs targeting the web, Dart Web includes both a development time compiler (dartdevc) and a production time compiler (dart2js).
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See LICENSE and PATENT_GRANT.
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