LLVM targets

[axl]

hi folks. I was trying to compile some cross platform code using llvm and clang.

I'm starting slow. with a helloworld.c program.

the sys-devel/llvm package has a LLVM_TARGETS flag which mentions ARM and aarch64 and powepc. clang has one.

however compiler-rt doesn't. As a result it only builds libclang_rt.builtins-i386.a and libclang_rt.builtins-x86_64.a.

as a result when you try:

clang -target aarch64-unknown-linux-gnu -arch aarch64-unknown-linux-gnu test.c -o test -I/usr/aarch64-unknown-linux-gnu/usr/ -L/usr/aarch64-unknown-linux-gnu/usr/lib64 -fuse-ld=lld -v

you get something like:

[axl]

I suck at writing. I started looking into llvm and clang for all the wrong reasons. I was trying to compile some stuff for my jailbroken ipad. Once you look into this, you find out that currently it is easier to compile stuff for apple using clang and llvm than gcc. Another bad reason was that I was curious if clang can compile kernels. Cross-compile code. Compile code through distcc. And last but not least, if I could speed up compiling at least some stuff, using a GPU instead of a cpu. These were my targets going into this thing.

I already had a toe in. I have multiple crossdev toolchains installed on my machine. the arm64, armv6, armv7, powerpc, powerpc64. once you install with crossdev the initial packages, you can at least easily cross compile kernels. easily. even using genkernel. as long as you set everything right, you can do it. and even with distcc on top. which is absolutely great. I think, if you look at what crossdev does... it installs a binutils aimed at manipulating arm binaries, but it runs on x86, just as gcc (runs on x86 - but makes stuff for arm) and finally glibc. that is installed in /usr/$CHOST/lib and is arm code.

At this point, all binutils (the original binutils for the host system, the cross-arm-binutils, the cross-armv7a, the cross-aarch64 and so on) were compiled with multitarget useflag, and llvm / clang with gold, and also compiled lld. on the host. if you look at what I posted yesterday, at this point, if you try to use clang to build code for another platform, it will complain of 2 things. 1 is that it can't find libclang_rt.builtins-aarch64.a. or armhf.a. You can just ignore that. In fact this is one of the issues I have to solve tomorrow. Can't figure out what is pulling that and how to disable it. Because it will work without it.

The second thing it will complain is the fact that which ever files I tried to pull for crtbegin.o crtend.o (I think this is how they are called, they are gcc files for sure and are usually in /usr/$CHOST/lib/gcc/$VER/) and I tried them all... clang would complain that it can't mix arm code with x86 code and those files are not good. I was pointing out to clang using -L paramenter. and he didn't like any of them, because all of them even those compiled by crossdev are just x86 files. so I would need their version in arm. so after cross-fix-root and adding distcc to features in make.conf CHOST=$CHOST cross-emerge gcc. now we have the arm versions or the gcc crt files, right there in where clangs expects them to be to link properly. So now when I run:

[nikolis]

Question with the same title

[The Main Man]

In package.use

[Ionen]

It can be used by rust as well, I feel it makes more sense to just set it globally, like:

[nikolis]

I turned off the targets, temporarily do not need them because i run gentoo in virtualbox.
Thank you.