[llvm-dev] Debug information with clang-cl on Windows

[Tobias Hieta via llvm-dev]

I forgot a pretty important piece of information, we are currently on
LLVM 11.0.1.

On Tue, Mar 9, 2021 at 9:37 AM Tobias Hieta <tobias at plexapp.com> wrote:
>
> Hello,
>
> We recently switched our windows builds from the CL compiler to
> clang-cl. This was a pretty big jump in terms of code generation and
> having a uniform compiler across all the major platforms.
>
> Our setup is that our Windows developer use MSVC as the IDE and
> compile with our own build of clang-cl and link with lld-link.
>
> Some of the developers noticed that some of the debug information are
> not as good as with CL. Or rather some variables seems to be optimized
> out, this is what the IDE says, see attached screenshot. I have tried
> to figure out if there is a rhyme and reason to what variables are
> gone - but I have not been able to see any pattern.
>
> Our command line is:
>
> clang-cl.exe /nologo -DUNICODE -DUSE_BREAKPAD -DWIN32
> -DWIN32_LEAN_AND_MEAN -DWINVER=0x0601 -D_CRT_NONSTDC_NO_DEPRECATE
> -D_CRT_SECURE_NO_WARNINGS -D_LEGACY_NAT_TRAVERSAL_ -D_REENTRANT
> -D_SCL_SECURE_NO_WARNINGS -D_SILENCE_ALL_CXX17_DEPRECATION_WARNINGS
> -D_UNICODE -D_WIN32_WINNT=0x0601 -D_WINSOCK_DEPRECATED_NO_WARNINGS
> -Iincludes -m32 -fdiagnostics-absolute-paths
> --target=i686-windows-msvc -m32 /DWIN32 /D_WINDOWS /GR /EHsc /Zi /Ob0
> /Od /RTC1 -MDd /Zm512 /EHsc /bigobj /W3 -Werror -Wsign-compare
> -Wno-reorder-ctor -Wno-delete-non-virtual-dtor -Wunused-variable
> -Wuninitialized -std:c++14
>
> Is there any good way to debug this or is it a known limitation with
> clang-cl or 32 bit (we don't do 64 yet - but with clang-cl we hope to
> move towards that soon). Or am I missing some flags?
>
> Thanks,
> Tobias