LLVM

From this ELI5 https://www.reddit.com/r/learnprogramming/comments/t6y74/eli5_what_is_llvm_can_it_be_used_for_general/

• Normally source code to assembly

• LLVM is a middleman VM that can make things easier on both ends (source code to LLVM, LLVM to assembly)

• You now only need two things (depending)

  • creating new high level language: front end (source code to LLVM)
  • creating new chip/instruction set: LLVM assembler (LLVM to assembly)

• Previous state of the world before LLVM: must be responsible from source code all the way to assembly PER language PER chip = massive headache.

• practically high level assembly

• need to develop a front end (high level to LLVM)

• develop a back end (LLVM to ISA)

• compile time

  • translate symbolic to absolute address

• link time

  • external dependency link, still part of generating executable

• load time

  • putting executable in RAM

• run time

• JIT

Follow-up

• RISC vs CISC and chip ISA’s (instruction set architectures)
• JVM

More

• https://stackoverflow.com/questions/7901576/what-are-the-tradeoffs-of-performing-static-analysis-on-source-code-byte-code
• https://en.wikipedia.org/wiki/Comparison_of_application_virtualization_software
• https://www.hackingnote.com/en/versus/llvm-vs-jvm
• https://stackoverflow.com/questions/12191462/what-is-the-difference-in-byte-code-like-java-bytecode-and-files-and-machine-cod
• https://wiki.osdev.org/ELF
• http://www.cs.cmu.edu/afs/cs/academic/class/15745-s13/public/lectures/L3-LLVM-Overview-1up.pdf