Bruno Garcia
655675a7db
I'm going through the docs to ramp up with the split debug-info/DWARF stuff. In [this doc, I noticed a reference to `pkg/vm/bin/convert_stack_traces.dart`](https://github.com/dart-lang/sdk/blob/52f1502191e8668e3ec216eb52cedc47e574c334/runtime/docs/dwarf_stack_traces.md#using-the-stack-trace-converter-tool) but [this code was deleted (moved) in this commit](https://github.com/dart-lang/sdk/commit/a003d5e69ac860263895f0d4f1438cb2b5ae5053#diff-23252e156bc12255fd263fe5f59b6d42). The new file is in `pkg/native_stack_traces/bin/decode.dart` which is part of the [native_stack_traces package](https://pub.dev/packages/native_stack_traces). Closes https://github.com/dart-lang/sdk/pull/43201 https://github.com/dart-lang/sdk/pull/43201 GitOrigin-RevId: fbe926f8d1e3c0fa8cc9abcb045c9d8d750cc921 Change-Id: I5570a23af28cb66853bdc5c2835dcaf1390dd74f Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/160400 Reviewed-by: Tess Strickland <sstrickl@google.com> Commit-Queue: Vyacheslav Egorov <vegorov@google.com>
native_stack_traces
This package provides libraries and a utility for decoding non-symbolic stack traces generated by an AOT-compiled Dart application.
Converting stack traces
In some modes of AOT compilation, information on mapping execution points to source locations is no longer stored in the Dart image. Instead, this information is translated to separately stored debugging information. This debugging information can then be stripped from the application before shipping.
However, there is a drawback. Stack traces generated by such an application no longer includes file, function, and line number information (i.e., symbolic stack traces). Instead, stack trace frames simply include program counter information. Thus, to find the source information for these frames, we must use the debugging information. This means either keeping the original unstripped application, or saving the debugging information into a separate file.
Given this debugging information, the libraries in this package can turn
non-symbolic stack traces back into symbolic stack traces. In addition, this
package includes a command line tool decode whose output is the same as its
input except that non-symbolic stack traces are translated.
Using decode
Take the following Dart code, which we put in throws.dart. The inlining
pragmas are here just to ensure that bar is inlined into foo and that foo
is not inlined into bar, to illustrate how inlined code is handled in the
translated output.
@pragma('vm:prefer-inline')
bar() => throw null;
@pragma('vm:never-inline')
foo() => bar();
main() => foo();
Now we run the following commands:
# Make sure that we have the native_stack_traces package.
$ pub get native_stack_traces
$ pub global activate native_stack_traces
# We compile the example program, removing the source location information
# from the snapshot and saving the debugging information into throws.debug.
$ dart2native -k aot -S throws.debug -o throws.aotsnapshot throws.dart
# Run the program, saving the error output to throws.err.
$ dartaotruntime throws.aotsnapshot 2>throws.err
# Using the saved debugging information, we can translate the stack trace
# contained in throws.err to its symbolic form.
$ pub global run native_stack_traces:decode translate -d throws.debug -i throws.err
# We can also just pipe the output of running the program directly into
# the utility.
$ dartaotruntime throws.aotsnapshot |& \
pub global run native_stack_traces:decode translate -d throws.debug
Features and bugs
Please file feature requests and bugs at the issue tracker.