CODEWITHSUNDEEP
clangllvmlld
G Hatzsis
G Hatzsis

Reputation: 41

How can I link files compiled with clang -flto using lld?

I am trying to use llvm-lld to link an object that has been compiled with -flto.

I have the ld in the path call lld with all the arguments provided. I created a simple C++ program, which I compile with clang++:

#include <stdio.h>
int main() {
    printf("Goodbye cruel world\n");
    return 0;
}

Without the -flto flag I get an executable, with the -flto I get this error:

warning: ignoring unknown argument: -plugin
warning: ignoring unknown argument: -plugin-opt=mcpu=x86-64
Cannot open /tmp/a-f1a2a7.o: Exec format error
clang-3.8: error: linker command failed with exit code 1 (use -v to see invocation)

Here are the arguments being passed to the linker, I see that with -flto the plugin arguments are provided include this plugin option, yet it seems to be unsupported.

--eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o a.out /usr/lib64/gcc/x86_64-pc-linux-gnu/5.2.0/../../../../lib64/crt1.o /usr/lib64/gcc/x86_64-pc-linux-gnu/5.2.0/../../../../lib64/crti.o /usr/lib64/gcc/x86_64-pc-linux-gnu/5.2.0/crtbegin.o -L/usr/lib64/gcc/x86_64-pc-linux-gnu/5.2.0 -L/usr/lib64/gcc/x86_64-pc-linux-gnu/5.2.0/../../../../lib64 -L/lib/../lib64 -L/usr/lib/../lib64 -L/usr/lib64/gcc/x86_64-pc-linux-gnu/5.2.0/../../../../x86_64-pc-linux-gnu/lib -L/usr/lib64/gcc/x86_64-pc-linux-gnu/5.2.0/../../.. -L/mnt/data/tmp/dev/llvm/prev/bin/../lib -L/lib -L/usr/lib -plugin /mnt/data/tmp/dev/llvm/prev/bin/../lib/LLVMgold.so -plugin-opt=mcpu=x86-64 /tmp/a-f1a2a7.o -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/lib64/gcc/x86_64-pc-linux-gnu/5.2.0/crtend.o /usr/lib64/gcc/x86_64-pc-linux-gnu/5.2.0/../../../../lib64/crtn.o

Is there a way for lld to link this code?

Upvotes: 4

Views: 2796

Answers (1)

Laser
Laser

Reputation: 6960

Yes, you can do it by using gold-linker which supports LTO via plugins:

Here is the instructions how to build and run it

Upvotes: 0

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