4 ms·
This theory is cool, but I don't think it works, all things considered. PDEP and PEXT should have the same unfused behavior as SHLX, since they also do not chan
by pbsd 9y ago
This theory is cool, but I don't think it works, all things considered. PDEP and PEXT should have the same unfused behavior as SHLX, since they also do not change any flags, but they _do_ fuse. BEXTR should (or could) fuse, but doesn't. So I don't know.
- BeeOnRope 9y agoYou are right, so yeah I can't explain really why certain ops fuse and some don't. There doesn't seem to be a strong pattern.