[llvm-dev] 答复: How to add new arch for llvm-cov show?

Vedant Kumar via llvm-dev llvm-dev at lists.llvm.org
Wed Jan 23 08:11:36 PST 2019

> On Jan 23, 2019, at 1:24 AM, xuruobin <xuruobin at huawei.com> wrote:
> 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

I haven’t double-checked, but I thought this definition came from llvm/Support/ELF.h?

> (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?

Coverage support should be / is largely compatible with binutils, but you may have to watch out for this BFD bug: https://clang.llvm.org/docs/SourceBasedCodeCoverage.html#drawbacks-and-limitations

What is the error you see?


> 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
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