zkllvm_input contains files to build with zkllvm, I've build it with https://github.com/NilFoundation/zkllvm-template. This build output is placed in evm_placeholder_verification_input to build it with https://github.com/NilFoundation/evm-placeholder-verification.
I've added EVm proof verification to the evm-placeholder_verification fork as a pull request gladcow/evm-placeholder-verification#1 to simplify changes overview. Test for proof verification is marked with my comment.