On Mon, Jan 15, 2024 at 8:33 AM Eduard Zingerman <eddyz87@xxxxxxxxx> wrote: > > > [0] Updated LLVM > https://github.com/eddyz87/llvm-project/tree/bpf-inline-asm-polymorphic-r 1. // Use sequence 'wX = wX' if 32-bits ops are available. let Predicates = [BPFHasALU32] in { This is unnecessary conservative. wX = wX instructions existed from day one. The very first commit of the interpreter and the verifier recognized it. No need to gate it by BPFHasALU32. 2. case 'w': if (Size == 32 && HasAlu32) This is probably unnecessary as well. When bpf programmer specifies 'w' constraint, llvm should probably use it regardless of alu32 flag. aarch64 has this comment: case 'x': case 'w': // For now assume that the person knows what they're // doing with the modifier. return true; I'm reading it as the constraint is a final decision. Inline assembly shouldn't change with -mcpu flags.
