CODEWITHSUNDEEP
linux-kernelllvmllvm-clang
zqy787
zqy787

Reputation: 35

Is there any possible way for LLVM to generate .bc file while generating .o file?

I am tring to build linux kernel using clang/llvm. I am trying to save the .bc file while generating the .o file . I find LLVM have the API "writebitcodetofile" whcich can save the bc code to certain file, but I am not sure how to use it.

Upvotes: 0

Views: 905

Answers (1)

AlexDenisov
AlexDenisov

Reputation: 4117

There is a number of flags that can do that for you:

  • -flto enables Link-time optimization, which uses LLVM bitcode. In this case (almost) all the .o files will in fact contain the bitcode.
  • -save-temps tells clang to put the results of each intermediate phase into a separate file. Simple clang -save-temps main.c may output main.o, main.bc, main.i, main.s, or object file, bitcode file, preprocessed file, and assembly file, respectively.
  • -fembed-bitcode tells clang to include the bitcode representation of a file into the resulting object file. You can learn more about this here: https://jonasdevlieghere.com/libebc-ebcutil/

Note, however, that you won't get bitcode for assembly files.

Upvotes: 1

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