Summary:
Update StackFrame::GetSymbolContext to mirror the logic in
RegisterContextLLDB::InitializeNonZerothFrame that knows not to do the
pc decrement when the given frame is a signal trap handler frame or the
parent of one, because the pc may not follow a call in these frames.
Accomplish this by adding a behaves_like_zeroth_frame field to
lldb_private::StackFrame, set to true for the zeroth frame, for
signal handler frames, and for parents of signal handler frames.
Also add logic to propagate the signal handler flag from UnwindPlan to
the FrameType on the RegisterContextLLDB it generates, and factor out a
helper to resolve symbol and address range for an Address now that we
need to invoke it in four places.
Reviewers: jasonmolenda, clayborg, jfb
Reviewed By: jasonmolenda
Subscribers: labath, dexonsmith, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D64993
llvm-svn: 367691
The two sections usually contain the same information, and we rarely
have both kinds of entries for a single function. However, in theory the
debug_frame plan can be more complete, whereas eh_frame is only required
to be correct at places where exceptions can be thrown.
Reviewers: jasonmolenda, clayborg
Subscribers: lldb-commits
Differential Revision: https://reviews.llvm.org/D62374
llvm-svn: 361758
Summary:
This behavior is specified in the Section 6.4.2.3 (Register Rule
instructions) of the DWARF4 spec. We were not doing that, which meant
that any register rule which was relying on the cfa value being there
was not evaluated correctly (it was aborted due to "out of bounds"
access).
I'm not sure how come this wasn't noticed before, but I guess this has
something to do with the fact that dwarf unwind expressions are not used
very often, and when they are, the situation is so complicated that the
CFA is of no use. I noticed this when I started emitting dwarf
expressions for the unwind information present in breakpad symbol files.
Reviewers: jasonmolenda, clayborg
Subscribers: aprantl, lldb-commits
Differential Revision: https://reviews.llvm.org/D61018
llvm-svn: 360158
Summary:
This argument was added back in 2010 (r118882) to support the ability to unwind
from functions whose eh_frame entry does not cover the entire range of
the function.
However, due to the caching happening in FuncUnwinders, this solution is
very fragile. FuncUnwinders will cache the plan it got from eh_frame
regardless of the value of the current_offset, so our ability to unwind
from a given function depended what was the value of "current_offset" the
first time that this function was called.
Furthermore, since the "image show-unwind" command did not know what's
the right offset to pass, this created an unfortunate situation where
"image show-unwind" would show no valid plans for a function, even
though they were available and being used.
In this patch I implement the feature slightly differently. Instead of
giving just a base address to the eh_frame unwinder, I give it the
entire range we are interested in. Then, I change the unwinder to return
the first plan that covers (even partially) that range. This way even a
partial plan will be returned, regardless of the address in the function
where we are stopped at.
This solution is still not 100% correct, as it will not handle a
function which is covered by two independent fde entries. However, I
don't expect anybody will write this kind of functions, and this wasn't
handled by the previous implementation either. If this is ever needed in
the future. The eh_frame unwinder can be extended to return "composite"
unwind plans created by merging sevelar fde entries.
I also create a test which triggers this scenario. As doing this is
virtually impossible without hand-written assembly, the test only works
on x86 linux.
Reviewers: jasonmolenda, clayborg
Subscribers: lldb-commits
Differential Revision: https://reviews.llvm.org/D60829
llvm-svn: 358964
Summary:
Previously we were printing the dwarf expressions in unwind rules simply
as "dwarf-expr". This patch uses the existing dwarf-printing
capabilities in lldb to enhance this dump output, and print the full
decoded dwarf expression.
Reviewers: jasonmolenda, clayborg
Subscribers: aprantl, lldb-commits
Differential Revision: https://reviews.llvm.org/D60949
llvm-svn: 358959
Joseph Tremoulet