Tess Strickland
83e9bd72ea
Adds the following command line options to gen_snapshot: * --macho-install-name: The name to use as the install name for the dynamic library (used in the LC_ID_DYLIB and LC_CODE_SIGNATURE load commands). If not provided, the output filename is used. * --[no-]macho-linker-signature: Whether or not gen_snapshot should generate an ad-hoc linker-signed signature. Defaults to true. The following command line option is macOS/iOS-specific: * --macho-rpath: Comma-delimited run paths that should be added at runtime to the current run path used for finding @rpath-prefixed dynamic libraries. Adds support to parsing rpath and dylib load commands to pkg/native_stack_traces's Mach-O parser in order to test the command line options appropriately. TEST=vm/dart/use_macho_options Issue: https://github.com/dart-lang/sdk/issues/60307 Change-Id: I17618578a7bff7851a88cdaf27f299f058f98dd3 Cq-Include-Trybots: luci.dart.try:vm-aot-mac-debug-x64-try,vm-aot-mac-debug-arm64-try,vm-aot-linux-debug-arm64-try,vm-aot-linux-debug-x64-try,pkg-mac-release-try,pkg-mac-release-arm64-try,pkg-linux-release-arm64-try,vm-aot-win-release-arm64-try,vm-aot-win-debug-x64-try Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/441920 Reviewed-by: Ryan Macnak <rmacnak@google.com> Commit-Queue: Tess Strickland <sstrickl@google.com>
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.
$ dart 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.
$ dart compile exe -S throws.debug throws.dart
# Run the program, saving the error output to throws.err.
$ ./throws.exe 2>throws.err
# Using the saved debugging information, we can translate the stack trace
# contained in throws.err to its symbolic form.
$ dart pub global run native_stack_traces:decode translate -d throws.debug -i throws.err
Features and bugs
Please file feature requests and bugs at the issue tracker.