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Martin Storsjö via llvm-dev

2020-Jan-09 21:00 UTC

[llvm-dev] LLD PDB Lines zero number issue

On Thu, 9 Jan 2020, David Blaikie via llvm-dev wrote:
> +rnk who works on COFF debugging things.
> 
>  My understanding is that this has nothing to do with the linker - but is a
> function of LLVM optimizations creating line zero debug locations. I
believe
> rnk & folks have disabled line zero emission for CodeView debug info in
some
> manner - perhaps that needs a flag? or Steven hasn't got a release with
that
> change in it?
I think I've run into that with dwarf as well, and there AFAIK it can be 
gotten rid of by adding "-mllvm -use-unknown-locations=Disable".

// Martin

Shi, Steven via llvm-dev

2020-Jan-10 01:42 UTC

head link

[llvm-dev] LLD PDB Lines zero number issue

Hi Martin,

I tried your suggestion of adding "-mllvm
-use-unknown-locations=Disable" in the clang CC flag to build test case in
my previous email, but it looks still not work in my side with llvm 9.0.0. 
Could you give me some more advices? Do I need to use the master LLVM instead of
the 9.0.0?



$ make -f makefile_clanglto_Oz

"/home/jshi19/llvm/clang+llvm-9.0.0-x86_64-linux-gnu-ubuntu-18.04/bin/clang"
-g  -m64 -mcmodel=small -target x86_64-unknown-windows -gcodeview -mllvm
-use-unknown-locations=Disable -flto -Oz -c -o main.obj  main.c

"nasm" -f win64 -o assembly.obj assembly.nasm

"/home/jshi19/llvm/clang+llvm-9.0.0-x86_64-linux-gnu-ubuntu-18.04/bin/llvm-lib"
/OUT:main.lib main.obj

"/home/jshi19/llvm/clang+llvm-9.0.0-x86_64-linux-gnu-ubuntu-18.04/bin/llvm-lib"
/OUT:assembly.lib assembly.obj

"/home/jshi19/llvm/clang+llvm-9.0.0-x86_64-linux-gnu-ubuntu-18.04/bin/lld-link"
/OUT:main.dll /Machine:X64 /DLL /ENTRY:main /DEBUG:GHASH /lldmap main.lib
assembly.lib



$
/home/jshi19/llvm/clang+llvm-9.0.0-x86_64-linux-gnu-ubuntu-18.04/bin/llvm-pdbutil
dump -l main.pdb

                           Lines

===========================================================
Mod 0000 | `assembly.obj`:

Mod 0001 | `/home/jshi19/llvm/wrongcode/lld-link5/lto.tmp`:

/home/jshi19/llvm/wrongcode/lld-link5/main.c (MD5:
5F82BB79FE2DA0B0549B784CFDC37D05)

  0001:00000004-0000001E, line/addr entries = 5

     3 00000004 !    0 00000008 !    5 0000000D !    0 00000012 !    9 00000017
!





Thanks

Steven Shi




> -----Original Message-----
> From: Martin Storsjö <martin at martin.st>
> Sent: Friday, January 10, 2020 5:00 AM
> To: David Blaikie <dblaikie at gmail.com>
> Cc: Shi, Steven <steven.shi at intel.com>; Reid Kleckner <rnk at
google.com>;
> llvm-dev <llvm-dev at lists.llvm.org>
> Subject: Re: [llvm-dev] LLD PDB Lines zero number issue
>
> On Thu, 9 Jan 2020, David Blaikie via llvm-dev wrote:
>
> > +rnk who works on COFF debugging things.
> >
> >  My understanding is that this has nothing to do with the linker - but
is a
> > function of LLVM optimizations creating line zero debug locations. I
believe
> > rnk & folks have disabled line zero emission for CodeView debug
info in
> some
> > manner - perhaps that needs a flag? or Steven hasn't got a release
with
> that
> > change in it?
>
> I think I've run into that with dwarf as well, and there AFAIK it can
be
> gotten rid of by adding "-mllvm -use-unknown-locations=Disable".
>
> // Martin-------------- next part --------------
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Shi, Steven via llvm-dev

2020-Jan-12 03:11 UTC

head link

[llvm-dev] LLD PDB Lines zero number issue

I checked the LLVM master code and find that the “-use-unknown-locations” option
and its related logic is only supported for Dwarf debug info as below. These
codes are missing in the Codeview side. It looks the “-use-unknown-locations”
option logic is not complex, could we port the code logic into
llvm\lib\CodeGen\AsmPrinter\CodeViewDebug.cpp as well? I’ve submitted a BZ for
this requirment: https://bugs.llvm.org/show_bug.cgi?id=44522

llvm-project\llvm\lib\CodeGen\AsmPrinter\DwarfDebug.cpp :
static cl::opt<DefaultOnOff> UnknownLocations(
    "use-unknown-locations", cl::Hidden,
    cl::desc("Make an absence of debug location information
explicit."),
    cl::values(clEnumVal(Default, "At top of block or after label"),
               clEnumVal(Enable, "In all cases"), clEnumVal(Disable,
"Never")),
    cl::init(Default));
... ...
    // If user said Don't Do That, don't do that.
    if (UnknownLocations == Disable)
      return;


This issue blocks the LLVM toolchain debugging capability for UEFI firmware.
Please help to add the support. Thank you in advance!



Thanks

Steven Shi

From: Shi, Steven
Sent: Friday, January 10, 2020 9:43 AM
To: Martin Storsjö <martin at martin.st>; David Blaikie <dblaikie at
gmail.com>
Cc: Reid Kleckner <rnk at google.com>; llvm-dev <llvm-dev at
lists.llvm.org>; Rui Ueyama <ruiu at google.com>
Subject: RE: [llvm-dev] LLD PDB Lines zero number issue


Hi Martin,

I tried your suggestion of adding "-mllvm
-use-unknown-locations=Disable" in the clang CC flag to build test case in
my previous email, but it looks still not work in my side with llvm 9.0.0. 
Could you give me some more advices? Do I need to use the master LLVM instead of
the 9.0.0?



$ make -f makefile_clanglto_Oz

"/home/jshi19/llvm/clang+llvm-9.0.0-x86_64-linux-gnu-ubuntu-18.04/bin/clang"
-g  -m64 -mcmodel=small -target x86_64-unknown-windows -gcodeview -mllvm
-use-unknown-locations=Disable -flto -Oz -c -o main.obj  main.c

"nasm" -f win64 -o assembly.obj assembly.nasm

"/home/jshi19/llvm/clang+llvm-9.0.0-x86_64-linux-gnu-ubuntu-18.04/bin/llvm-lib"
/OUT:main.lib main.obj

"/home/jshi19/llvm/clang+llvm-9.0.0-x86_64-linux-gnu-ubuntu-18.04/bin/llvm-lib"
/OUT:assembly.lib assembly.obj

"/home/jshi19/llvm/clang+llvm-9.0.0-x86_64-linux-gnu-ubuntu-18.04/bin/lld-link"
/OUT:main.dll /Machine:X64 /DLL /ENTRY:main /DEBUG:GHASH /lldmap main.lib
assembly.lib



$
/home/jshi19/llvm/clang+llvm-9.0.0-x86_64-linux-gnu-ubuntu-18.04/bin/llvm-pdbutil
dump -l main.pdb

                           Lines

===========================================================
Mod 0000 | `assembly.obj`:

Mod 0001 | `/home/jshi19/llvm/wrongcode/lld-link5/lto.tmp`:

/home/jshi19/llvm/wrongcode/lld-link5/main.c (MD5:
5F82BB79FE2DA0B0549B784CFDC37D05)

  0001:00000004-0000001E, line/addr entries = 5

     3 00000004 !    0 00000008 !    5 0000000D !    0 00000012 !    9 00000017
!





Thanks

Steven Shi




> -----Original Message-----
> From: Martin Storsjö <martin at martin.st<mailto:martin at
martin.st>>
> Sent: Friday, January 10, 2020 5:00 AM
> To: David Blaikie <dblaikie at gmail.com<mailto:dblaikie at
gmail.com>>
> Cc: Shi, Steven <steven.shi at intel.com<mailto:steven.shi at
intel.com>>; Reid Kleckner <rnk at google.com<mailto:rnk at
google.com>>;
> llvm-dev <llvm-dev at lists.llvm.org<mailto:llvm-dev at
lists.llvm.org>>
> Subject: Re: [llvm-dev] LLD PDB Lines zero number issue
>
> On Thu, 9 Jan 2020, David Blaikie via llvm-dev wrote:
>
> > +rnk who works on COFF debugging things.
> >
> >  My understanding is that this has nothing to do with the linker - but
is a
> > function of LLVM optimizations creating line zero debug locations. I
believe
> > rnk & folks have disabled line zero emission for CodeView debug
info in
> some
> > manner - perhaps that needs a flag? or Steven hasn't got a release
with
> that
> > change in it?
>
> I think I've run into that with dwarf as well, and there AFAIK it can
be
> gotten rid of by adding "-mllvm -use-unknown-locations=Disable".
>
> // Martin-------------- next part --------------
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