[LLVMbugs] [Bug 18279] New: llvm build with -flto installs libclang_rt.* archives that contain bitcode

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=18279

            Bug ID: 18279
           Summary: llvm build with -flto installs libclang_rt.* archives
                    that contain bitcode
           Product: compiler-rt
           Version: unspecified
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: compiler-rt
          Assignee: unassignedbugs at nondot.org
          Reporter: octoploid at yandex.com
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

When llvm is build with -flto installs libclang_rt.* archives that contain
bitcode.

For example:

markus at x4 ~ % clang -fsanitize=undefined -O2 -g un.c
/usr/lib64/gcc/x86_64-pc-linux-gnu/4.9.0/../../../../x86_64-pc-linux-gnu/bin/ld:
error: /usr/local/bin/../lib/clang/3.4/lib/linux/libclang_rt.san-x86_64.a:
member at 812 is not an ELF object
/usr/lib64/gcc/x86_64-pc-linux-gnu/4.9.0/../../../../x86_64-pc-linux-gnu/bin/ld:
error: /usr/local/bin/../lib/clang/3.4/lib/linux/libclang_rt.san-x86_64.a:
member at 44656 is not an ELF object
...
un.c:3: error: undefined reference to '__ubsan_handle_shift_out_of_bounds'
clang-3.4: error: linker command failed with exit code 1 (use -v to see
invocation)

(-flto works fine, because it enables the linker plugin:)
markus at x4 ~ % clang -flto -fsanitize=undefined -O2 -g un.c
markus at x4 ~ % 

(enabling the linker plugin by hang also works:)
markus at x4 ~ % clang -Wl,-plugin /usr/local/bin/../lib/LLVMgold.so
-Wl,-plugin-opt=mcpu=x86-64 -fsanitize=undefined -O2 -g un.c
markus at x4 ~ %  

One solution would be to always disable -flto for compiler-rt during the build.
Another one to enable the linker plugin by default for -flto builds in general.

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