0faf56378e
1) It shaves of a few cycles from the data dependency chain. By using "shrd" instead of a load. 2) The important loop is finding small copies (4-12) which are either "copy 1", or "copy 2" depending if the offset fits <2048. It turns out that this is a branch that is mispredicted often. Due to the long dependency chain the CPU is running with IPC~1 anyway so we can freely add instructions to instead emit copies branchfree. This reduces the branch misspredicts from 15% to 11% (for BM_ZFlat/6 txt1) and from 5.6% to 4% (for BM_ZFlat/10 or pb). PiperOrigin-RevId: 303328967
60 KiB
60 KiB