[SOLVED] clang target issue

Haythem · 08-05-2016, 06:49 PM

I'm building from 7.9 version of the book, I built llvm with clang but I'm not able to compile simple programs by clang.

I bieleve the problem is the default target in clang is different than my lfs target

Code:

root@lfs://usr/lib64/gcc# clang --version
clang version 3.8.1 (tags/RELEASE_381/final)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

However my gcc target is:

Code:

/usr/lib64/gcc/x86_64-lfs-linux/5.3.0/

I can compile simple programs by clang with:

Code:

clang --target=x86_64-lfs-linux foo.c

My question is how to compile llvm with default target name x86_64-lfs-linux
I tried -DLLVM_TARGETS_TO_BUILD="x86_64-lfs-linux;AMDGPU" but doesn't compile.

Thanks you

Krejzi · 08-08-2016, 12:42 PM

First of all, your LFS target is wrong if you followed the book. It should be x86_64-pc-linux-gnu on GCC 5.x and later. And the target doesn't really matter for clang. You'd need to patch it manually so it displays the correct triple (again, which doesn't matter at all).

Haythem · 08-08-2016, 01:42 PM

Quote:

Originally Posted by Krejzi

First of all, your LFS target is wrong if you followed the book. It should be x86_64-pc-linux-gnu on GCC 5.x and later. And the target doesn't really matter for clang. You'd need to patch it manually so it displays the correct triple (again, which doesn't matter at all).

I'm following the book with minor changes like buildign x86_64 version, and gcc target triplet, (very few minor changes). However I could fix the target triplet name by setting this variable during build -DLLVM_DEFAULT_TARGET_TRIPLE.

Krejzi · 08-08-2016, 01:43 PM

Again, out of curiosity, why does the clang target matter?

Haythem · 08-08-2016, 02:00 PM

because if default target is not set correctly, clang shows this error when trying to compile foo.c program:
/

Code:

usr/bin/ld: cannot find crtbegin.o: No such file or directory
/usr/bin/ld: cannot find -lgcc
clang-3.8: error: linker command failed with exit code 1 (use -v to see invocation)

and I have to pass --target=x86_64-lfs-linux to clang everytime. I thin it should be the case even with lfs book target, have to set --target=x86_64-pc-linux-gnu otherwise clang wont work (i haven't tested it though).

Krejzi · 08-08-2016, 02:07 PM

Ah, right. That makes sense. Again, out of curiosity, why did you change the gcc target to contain lfs? Branding, marketing, something else?

Haythem · 08-08-2016, 02:11 PM

I use slackware and the gcc target for slackware is x86_64-slackware-linux-gnu. I don't have to stick with default gcc target so changed it.