llvm dev - Jan 2019 - How to add new arch for llvm-cov show?

Hi all,

I'm trying to support llvm-cov for a new architecture and I have
successfully built compiler-rt for my arch. Following steps shown in
https://clang.llvm.org/docs/SourceBasedCodeCoverage.html , I encountered an
error for the last step(step of llvm-cov show).
The command line was (supposed my arch is XXXX)

"llvm-cov show -arch=XXXX ./foo -instr-profile=foo.profdata"

and the error was

"Failed to load coverage: No object file for requested architecture."

I think I should add my arch information to somewhere(maybe an llvm-cov support
list?) but I don't know where to add these information. Can someone give me
some suggestions?

Best Regards,
Ruobin.

Hi Ruobin,
> On Jan 21, 2019, at 5:21 PM, xuruobin via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> Hi all,
> 
> I'm trying to support llvm-cov for a new architecture and I have
successfully built compiler-rt for my arch. Following steps shown in
https://clang.llvm.org/docs/SourceBasedCodeCoverage.html , I encountered an
error for the last step(step of llvm-cov show).
> The command line was (supposed my arch is XXXX)
> 
> "llvm-cov show -arch=XXXX ./foo -instr-profile=foo.profdata"
> 
> and the error was
> 
> "Failed to load coverage: No object file for requested
architecture."
> 
> I think I should add my arch information to somewhere(maybe an llvm-cov
support list?) but I don't know where to add these information. Can someone
give me some suggestions?
You’ll need to teach libObject about this architecture. Specifically, the
coverage reader checks that calling getArch() on a loaded ObjectFile matches
Triple(Arch).getArch() (see loadBinaryFormat in CoverageMappingReader.cpp).

best,
vedant

> 
> Best Regards,
> Ruobin.
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

Hi vedant,

  The program didn't pass the checking "OF->getArch() !=
Triple(Arch).getArch()" loadBinaryFormat in CoverageMappingReader.cpp and
returned an error. It's because "OF->getArch()" returned null
and "Triple(Arch).getArch()" returned XXXX(name of my arch).
  The returned value of  " OF->getArch()" is decided by "
EF.getHeader()->e_machine" but I found "e_machine" is defined
somewhere in MCAssembler(My compiler uses binutils as assembler) . Although I
make some hacks to pass this checking, I still get other errors. So my problem
is whether llvm-cov has to work with MCAssembler and is it possible to do it
with binutils?

Best,
Ruobin
> -----邮件原件-----
> 发件人: vsk at apple.com [mailto:vsk at apple.com]
> 发送时间: 2019年1月23日 1:24
> 收件人: xuruobin <xuruobin at huawei.com>
> 抄送: llvm-dev at lists.llvm.org; Yuchao (Michael)
> <michael.yuchao at huawei.com>
> 主题: Re: [llvm-dev] How to add new arch for llvm-cov show?
> 
> Hi Ruobin,
> 
> > On Jan 21, 2019, at 5:21 PM, xuruobin via llvm-dev <llvm-dev at
lists.llvm.org>
> wrote:
> >
> > Hi all,
> >
> > I'm trying to support llvm-cov for a new architecture and I have
successfully
> built compiler-rt for my arch. Following steps shown in
> https://clang.llvm.org/docs/SourceBasedCodeCoverage.html , I encountered
> an error for the last step(step of llvm-cov show).
> > The command line was (supposed my arch is XXXX)
> >
> > "llvm-cov show -arch=XXXX ./foo -instr-profile=foo.profdata"
> >
> > and the error was
> >
> > "Failed to load coverage: No object file for requested
architecture."
> >
> > I think I should add my arch information to somewhere(maybe an
llvm-cov
> support list?) but I don't know where to add these information. Can
> someone give me some suggestions?
> 
> You’ll need to teach libObject about this architecture. Specifically, the
> coverage reader checks that calling getArch() on a loaded ObjectFile
matches
> Triple(Arch).getArch() (see loadBinaryFormat in
> CoverageMappingReader.cpp).
> 
> best,
> vedant
> 
> 
> >
> > Best Regards,
> > Ruobin.
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev