xuruobin via llvm-dev
2018-Dec-22 09:29 UTC
[llvm-dev] How to compile glibc with clang/llvm?
To whom it may concern, Is there a way to build glibc with clang/llvm? I’m working on enabling llvm-cov for my compiler which is a totally new arch with a libc.a built from newlib. I successfully built compiler-rt but when I typed the command ` clang++ --target=xxx -fprofile-instr-generate -fcoverage-mapping foo.cc -o foo`, the linker failed because of undefined reference to `mmap'/`ftruncate'/`mkdir'. I found these functions are supported by glibc but I cannot bulid glibc with clang/llvm(configure gave me an error “These critical programs are missing or too old: compiler”). So I want to know how can I compile glibc with clang/llvm or are there some WIP patches to help me with this requirement? Thanks, Ruobin.
Kristina Brooks via llvm-dev
2018-Dec-23 10:51 UTC
[llvm-dev] How to compile glibc with clang/llvm?
Hi. I've managed to do it before, with a lot of patches to Glibc, as well as ld.so and getting basic programs to start with it. However, a lot of tests did not pass and in general I abandoned it due to the fact that Glibc source code is not very easy to work with. I can upload it somewhere, not sure if there is any general interest in this kind of thing. I think current GRTE may also be build-able with Clang (my fork was based on older GRTE which had unfinished patches to support Clang), though I haven't had the time to look at that recently. I should add a huge disclaimer: this won't be easy and requires understanding the macro hell in glibc, GRTE relies on some hacky uses of `_Pragma` to supplement for some macros otherwise not possible with Clang. Even if you do get it to build I think it may be a waste of time to try and just implement the missing symbols in your case (or figure out why they're not being exported). Thanks. On 22/12/2018 09:29, xuruobin via llvm-dev wrote:> To whom it may concern, > > Is there a way to build glibc with clang/llvm? I’m working on enabling llvm-cov for my compiler which is a totally new arch with a libc.a built from newlib. I successfully built compiler-rt but when I typed the command ` clang++ --target=xxx -fprofile-instr-generate -fcoverage-mapping foo.cc -o foo`, the linker failed because of undefined reference to `mmap'/`ftruncate'/`mkdir'. I found these functions are supported by glibc but I cannot bulid glibc with clang/llvm(configure gave me an error “These critical programs are missing or too old: compiler”). So I want to know how can I compile glibc with clang/llvm or are there some WIP patches to help me with this requirement? > > Thanks, > Ruobin. > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >-------------- next part -------------- A non-text attachment was scrubbed... Name: smime.p7s Type: application/pkcs7-signature Size: 3992 bytes Desc: S/MIME Cryptographic Signature URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20181223/6456e219/attachment.bin>
Kristina Brooks via llvm-dev
2018-Dec-23 10:59 UTC
[llvm-dev] How to compile glibc with clang/llvm?
Hi. Actually from reading the README, it seems to imply that it can be built with Clang 6.0.0 and above now, though it does incorporate a lot of patches not specific to Clang building so you will end up with them as well: ---------------------------------------------------------------------------- BUILDING GRTE WITH CLANG GRTE v5 and later can also be built with clang and (optionally) lld. LLVM support for GNU source code continues to evolve (as of June 2018), so the process is less straightforward, and likely to change from what is documented here. There are a number of glibc patches that make this work, including additional configure options mentioned below. The minimum version of clang is 6.0.0. If lld is to be used for linking, it needs to be newer than 6.0.0. Configure: CC=path-to-llvm/clang CXX=path-to-llvm/clang++ \ ../glibc/configure --disable-werror --with-clang --disable-float128 \ --with-lld --with-default-link --disable-multi-arch --prefix=/something ------------------------------------------------------------------------------ On 23/12/2018 02:51, Kristina Brooks wrote:> Hi. > > I've managed to do it before, with a lot of patches to Glibc, as well as ld.so and getting basic programs to start with > it. However, a lot of tests did not pass and in general I abandoned it due to the fact that Glibc source code is not > very easy to work with. > > I can upload it somewhere, not sure if there is any general interest in this kind of thing. I think current GRTE may > also be build-able with Clang (my fork was based on older GRTE which had unfinished patches to support Clang), though I > haven't had the time to look at that recently. > > I should add a huge disclaimer: this won't be easy and requires understanding the macro hell in glibc, GRTE relies on > some hacky uses of `_Pragma` to supplement for some macros otherwise not possible with Clang. Even if you do get it to > build I think it may be a waste of time to try and just implement the missing symbols in your case (or figure out why > they're not being exported). > > Thanks. > > On 22/12/2018 09:29, xuruobin via llvm-dev wrote: >> To whom it may concern, >> >> Is there a way to build glibc with clang/llvm? I’m working on enabling llvm-cov for my compiler which is a totally new arch with a libc.a built from newlib. I successfully built compiler-rt but when I typed the command ` clang++ --target=xxx -fprofile-instr-generate -fcoverage-mapping foo.cc -o foo`, the linker failed because of undefined reference to `mmap'/`ftruncate'/`mkdir'. I found these functions are supported by glibc but I cannot bulid glibc with clang/llvm(configure gave me an error “These critical programs are missing or too old: compiler”). So I want to know how can I compile glibc with clang/llvm or are there some WIP patches to help me with this requirement? >> >> Thanks, >> Ruobin. >> _______________________________________________ >> LLVM Developers mailing list >> llvm-dev at lists.llvm.org >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >> >-------------- next part -------------- A non-text attachment was scrubbed... Name: smime.p7s Type: application/pkcs7-signature Size: 3992 bytes Desc: S/MIME Cryptographic Signature URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20181223/2a6ba947/attachment.bin>
David Jones via llvm-dev
2018-Dec-24 00:56 UTC
[llvm-dev] How to compile glibc with clang/llvm?
Is your only problem that you don't have definitions for mmap/ftruncate/mkdir? If so, then you don't need to compile glibc. You merely need to solve the problem you actually have: you need a C library for your system calls. I have no idea what operating system you are running on your target, but the function names suggest it's Unix-like. Unix-like operating systems typically implement system calls as a trap to the operating system using an instruction specially built for this purpose. To this end, the "mmap" function in glibc merely arranges to get the arguments in the correct registers (or possibly the stack), and then invokes the proper trap. Perhaps 10 lines of assembly in all. If you can figure out the calling convention for your system calls, then you can easily write your own syscall library in assembler, for each call you require, which you can then link in, in addition to whatever else you are using. On Sat, Dec 22, 2018 at 4:29 AM xuruobin via llvm-dev < llvm-dev at lists.llvm.org> wrote:> To whom it may concern, > > Is there a way to build glibc with clang/llvm? I’m working on > enabling llvm-cov for my compiler which is a totally new arch with a libc.a > built from newlib. I successfully built compiler-rt but when I typed the > command ` clang++ --target=xxx -fprofile-instr-generate -fcoverage-mapping > foo.cc -o foo`, the linker failed because of undefined reference to > `mmap'/`ftruncate'/`mkdir'. I found these functions are supported by glibc > but I cannot bulid glibc with clang/llvm(configure gave me an error “These > critical programs are missing or too old: compiler”). So I want to know how > can I compile glibc with clang/llvm or are there some WIP patches to help > me with this requirement? > > Thanks, > Ruobin. > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20181223/f6464096/attachment.html>