6b4079e05e
5 Commits
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Seth Brenith
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4d0360aa84 |
[tools] Add list of classes to v8_debug_helper
This change extends v8_debug_helper to export a new method that returns a list of all known heap object types. Why? We can substantially improve the user experience in our work-in- progress WinDbg extension if we register handlers not only for v8::internal::Object but for every specific HeapObject type. This has two benefits: - You save a click: if you're expanding a local variable of a more specific type than Object, you can see properties immediately rather than first needing to expand a sub-item that casts the variable to Object. - You retain the type hint: GetObjectProperties accepts a type hint string, and it's super important to pass it when working in a crash dump because the object's Map is probably inaccessible. If we have to cast to Object first, we lose this data. Bug: v8:9376 Change-Id: I4d635a1826574a3d08ac657e848e1fe7b83849fe Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1822859 Reviewed-by: Tobias Tebbi <tebbi@chromium.org> Reviewed-by: Jakob Gruber <jgruber@chromium.org> Commit-Queue: Seth Brenith <seth.brenith@microsoft.com> Cr-Commit-Position: refs/heads/master@{#64331} |
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Seth Brenith
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1d3c4975be |
[tools] Use instance types of known Maps in v8_debug_helper
If we can read an object's Map pointer but not any data from the Map itself, we may still be able to accurately describe the object's type if the Map pointer matches one of the known Maps from the snapshot. GetObjectProperties uses that data in one of two ways: - If it is sure that the Map pointer matches a known Map, then it uses the type from that Map and continues as if it read the type normally. - If the Map pointer is at the right offset within a heap page to match a known Map, but the caller didn't provide the addresses of the first pages in Map space or read-only space, then the type of that Map is just a guess and gets returned in a separate array. This gives the caller the opportunity to present guessed types to the user, and perhaps call again using the guessed type as the type hint. Bug: v8:9376 Change-Id: I187f67b77e76699863a14534a9d635b79f654124 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1787986 Commit-Queue: Seth Brenith <seth.brenith@microsoft.com> Reviewed-by: Jakob Gruber <jgruber@chromium.org> Reviewed-by: Michael Achenbach <machenbach@chromium.org> Reviewed-by: Tobias Tebbi <tebbi@chromium.org> Cr-Commit-Position: refs/heads/master@{#63908} |
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Seth Brenith
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0921e8f28b |
Reland "Add postmortem debugging helper library"
This is a reland of
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Zhi An Ng
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6747e3a186 |
Revert "Add postmortem debugging helper library"
This reverts commit
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Seth Brenith
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517ab73fd7 |
Add postmortem debugging helper library
This change begins to implement the functionality described in https://docs.google.com/document/d/1evHnb1uLlSbvHAAsmOXyc25x3uh1DjgNa8u1RHvwVhk/edit# for investigating V8 state in crash dumps. This change adds a new library, v8_debug_helper, for providing platform- agnostic assistance with postmortem debugging. This library can be used by extensions built for debuggers such as WinDbg or lldb. Its public API is described by debug-helper.h; currently the only method it exposes is GetObjectProperties, but we'd like to add more functionality over time. The API surface is restricted to plain C-style structs and pointers, so that it's easy to link from a debugger extension built with a different toolchain. This change also adds a new cctest file to exercise some basic interaction with the new library. The API function GetObjectProperties takes an object pointer (which could be compressed, or weak, or a SMI), and returns a string description of the object and a list of properties the object contains. For now, the list of properties is entirely based on Torque object definitions, but we expect to add custom properties in future updates so that it can be easier to make sense of complex data structures such as dictionaries. GetObjectProperties does several things that are intended to generate somewhat useful results even in cases where memory may be corrupt or unavailable: - The caller may optionally provide a type string which will be used if the memory for the object's Map is inaccessible. - All object pointers are compared against the list of known objects generated by mkgrokdump. The caller may optionally provide the pointers for the first pages of various heap spaces, to avoid spurious matches. If those pointers are not provided, then any matches are prefixed with "maybe" in the resulting description string, such as "maybe UndefinedValue (0x4288000341 <Oddball>)". Bug: v8:9376 Change-Id: Iebf3cc2dea3133c7811bcefcdf38d9458b02fded Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1628012 Commit-Queue: Seth Brenith <seth.brenith@microsoft.com> Reviewed-by: Yang Guo <yangguo@chromium.org> Reviewed-by: Michael Stanton <mvstanton@chromium.org> Cr-Commit-Position: refs/heads/master@{#62882} |