jankratochvil added a comment.
In D82378#2109330 <https://reviews.llvm.org/D82378#2109330>, @labath wrote:
> Now this situation is not actually handled by lldb's "augmenter", so the
> example somewhat shaky, but it does show that there are gaps in clang/llvm
> modelling of unwind info.
Good to know but ... I do not see how is this `stdcall` unwinding bug related
to this issue whether to use `.eh_frame` or not -
`UnwindAssembly_x86::AugmentUnwindPlanFromCallSite` cannot verify any
`.eh_frame` is 100% valid.
> As for the DW_AT_producer idea, the main gotcha I see there is that
> eh/debug_frame is supposed to be usable even without the rest of the debug
> info.
Producer is also recorded in `.gnu.build.attributes` which is in the main
binary (not in external `.debug` info):
$ annocheck --enable-notes /bin/bash
Notes: Range: 0x304e0 .. 0xe22e9.
[O] Tool: running gcc 10.1.1 20200507
Notes: Range: 0x311f0 .. 0xe26a5.
[O] Tool: running gcc 10.1.1 20200507
$ readelf -Wn /bin/bash
Displaying notes found in: .gnu.build.attributes
Owner Data size Description
GA$<tool>running gcc 10.1.1 20200507 0x00000000 OPEN Applies
to region from 0x304e0 to 0xe22e9
GA$<tool>running gcc 10.1.1 20200507 0x00000000 OPEN Applies
to region from 0x311f0 to 0xe26a5
Although in fact one does not need to parse the notes at all as if there exist
such annobin notes one can already guarantee the compiler is new enough.
> the need for a fallback makes the idea less appealing.
Fallback without installed external debuginfo would not work much but a
fallback for old binaries still without annobin notes is not so bad IMO.
> The other problem with that is that we would actually have to gather
> information about which compilers report the unwind info correctly.
non-clang/non-gcc compilers can contribute whitelist entries themselves. Such
whitelisting would not regress the existing behavior, it would only further
improve the whitelisted clang+gcc compilers.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D82378/new/
https://reviews.llvm.org/D82378
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