[X86][AMX] Try to hoist AMX shapes' def

Authored by pengfei on Apr 21 2021, 6:10 PM.


[X86][AMX] Try to hoist AMX shapes' def

We request no intersections between AMX instructions and their shapes'
def when we insert ldtilecfg. However, this is not always ture resulting
from not only users don't follow AMX API model, but also optimizations.

This patch adds a mechanism that tries to hoist AMX shapes' def as well.
It only hoists shapes inside a BB, we can improve it for cases across
BBs in future. Currently, it only hoists shapes of which all sources' def
above the first AMX instruction. We can improve for the case that only
source that moves an immediate value to a register below AMX instruction.

Differential Revision: https://reviews.llvm.org/D101067