[PATCH] D115016: [CostModel][X86] Add i64 mul cost for avx as 1cy

Fri Dec 3 00:27:18 PST 2021

lebedev.ri added a comment.

In D115016#3168935 <https://reviews.llvm.org/D115016#3168935>, @pengfei wrote:

>> which is not true for most recent cpus.
>
> It seems Zen1's TP is still 2 in some cases. See Agner Fog's table and https://uops.info/table.html?search=mul%2064&cb_lat=on&cb_tp=on&cb_uops=on&cb_ports=on&cb_SKL=on&cb_ZENp=on&cb_ZEN2=on&cb_measurements=on&cb_doc=on&cb_base=on

Ack, this is the tragedy of these cost tables, they have to represent the worst-case, even if it is bogusly higher than the average.

> Another problem, do we need to add check for 64Bit?

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D115016/new/

https://reviews.llvm.org/D115016