Post #2409979

@wren6991@types.pl @fanf@mendeddrum.org @JamesWidman@mastodon.social AFAICT on first execute of a BB (so running with cold I$) you really do just get 3-wide decode, but the FE automatically inserts the dummy branches into the BTB as it's decoding long BBs, and second and later executions don't suffer this penalty. This is structurally very similar to what happens on the bigger cores for long BBs with 4-wide decoders and only the uOp cache being wide.