llvm-project/lldb/source/Plugins/UnwindAssembly/x86
Pavel Labath 5ed8765e2f [lldb/Unwind] Use eh_frame plan directly when it doesn't need to be augmented
Summary:
This fixes a bug in the logic for choosing the unwind plan. Based on the
comment in UnwindAssembly-x86, the intention was that a plan which
describes the function epilogue correctly does not need to be augmented
(and it should be used directly). However, the way this was implemented
(by returning false) meant that the higher level code
(FuncUnwinders::GetEHFrameAugmentedUnwindPlan) interpreted this as a
failure to produce _any_ plan and proceeded with other fallback options.
The fallback usually chosed for "asynchronous" plans was the
"instruction emulation" plan, which tended to fall over on certain
functions with multiple epilogues (that's a separate bug).

This patch simply changes the function to return true, which signals the
caller that the unmodified plan is ready to be used.

The attached test case demonstrates the case where we would previously
fall back to the instruction emulation plan, and unwind incorrectly --
the test asserts that the "augmented" eh_frame plan is used, and that
the unwind is correct.

Reviewers: jasonmolenda, jankratochvil

Subscribers: davide, echristo, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D82378
2020-06-26 11:46:47 +02:00
..
CMakeLists.txt
UnwindAssembly-x86.cpp [lldb/Unwind] Use eh_frame plan directly when it doesn't need to be augmented 2020-06-26 11:46:47 +02:00
UnwindAssembly-x86.h [lldb] Update header guards to be consistent and compliant with LLVM (NFC) 2020-02-17 23:15:40 -08:00
x86AssemblyInspectionEngine.cpp [lldb][NFC] Fix all formatting errors in .cpp file headers 2020-01-24 08:52:55 +01:00
x86AssemblyInspectionEngine.h [lldb] NFC remove DISALLOW_COPY_AND_ASSIGN 2020-06-02 13:23:53 -04:00