On Sun, Oct 6, 2024 at 2:00 AM Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > On Sat, 5 Oct 2024 at 16:37, H. Peter Anvin <hpa@xxxxxxxxx> wrote: > > > > Sadly, that is not correct; neither gcc nor clang uses lea: > > Looking around, this may be intentional. At least according to Agner, > several cores do better at "mov immediate" compared to "lea". > > Eg a RIP-relative LEA on Zen 2 gets a throughput of two per cycle, but > a "MOV r,i" gets four. That got fixed in Zen 3 and later, but > apparently Intel had similar issues (Ivy Bridge: 1 LEA per cycle, vs 3 > "mov i,r". Haswell is 1:4). Yes, this is the case. I just missed your reply when replying to Peter's mail with a not so precise answer. Uros.
