3 ms·

Modern processors don't handle self-modifying code efficiently. https://en.wikipedia.org/wiki/Self-modifying_code#Interaction_of_cache_and_self-modifying_code h

• userbinator 11y ago
  short sections of self-modifying code execute more slowly Unless you're optimising for size, SMC'ing little pieces is definitely going to be slower. But e.g. in loops that do a few hundred iterations, saving a cycle or two by getting rid of some opaque predicates quickly adds up and the cache/pipeline-flushing overhead (few hundred cycles at most) becomes insignificant. After all, as the parent comment says, a JIT is basically SMC'ing huge blocks of code, and it's definitely faster than the equivalent alternative of a bytecode interpreter.
  • wyager 11y ago
    Modern branch predictors handle opaque predicates (assuming you mean branches that don't change). Jump instructions in tight, repetitive loops on superscalar out-of-order processors are basically free.