[lldb-dev] Prologue instructions having line information

[Tamas Berghammer via lldb-dev]

Hi Carlos,

Thank your for looking into the LLDB failure. I looked into it briefly and
the issue is that we have have 2 function f and g where g is inlined into f
as the first call and this causes the first non-prologue line entry of f to
be inside the address range of g what means that when we step info f from
outside we will end up inside g instead. Previously the first line entry
for f matched with the start address of the inlined copy of g where LLDB
was able to handle the stepping properly.

For the concrete example you should compile
https://github.com/llvm-mirror/lldb/blob/26fea9dbbeb3020791cdbc46fbf3cc9d7685d7fd/packages/Python/lldbsuite/test/functionalities/inline-stepping/calling.cpp
with
"/mnt/ssd/ll/git/build/host-release/bin/clang-5.0 -std=c++11 -g -O0
-fno-builtin -m32 --driver-mode=g++ calling.cpp" and then observe
that caller_trivial_2 have a DW_AT_low_pc = 0x8048790 and the
inlined inline_trivial_1 inside it have a DW_AT_low_pc = 0x8048793 but the
first line entry after "Set prologue_end to true" is at 0x8048796 while
previously it was at 0x8048793.

Tamas

On Thu, Sep 14, 2017 at 9:59 AM Carlos Alberto Enciso via lldb-dev <
lldb-dev at lists.llvm.org> wrote:

> Hi,
>
> I have been working on a compiler issue, where instructions associated to
> the function prolog are assigned line information, causing the debugger to
> show incorrectly the beginning of the function body.
>
> For a full description, please see:
>
> https://reviews.llvm.org/D37625
> https://reviews.llvm.org/rL313047
>
> The submitted patch caused some LLDB tests to fail. I have attached the
> log failure.
>
> I have no knowledge about the test framework used by LLDB.
>
> What is the best way to proceed in this case?
>
> Thanks very much for your feedback.
>
> Carlos Enciso
>
>
>
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> lldb-dev at lists.llvm.org
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>
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