[PATCH] D95508: [X86] Fix tile config register spill issue for AMX

Sat Jan 30 22:56:31 PST 2021

xiangzhangllvm added inline comments.

================
Comment at: llvm/lib/Target/X86/X86PreTileConfig.cpp:300
+    if (Collect2)
+      collectCfgCalls(MBB, MI);
+
----------------
pengfei wrote:
> xiangzhangllvm wrote:
> > pengfei wrote:
> > > Doesn't it always just return `BB2AMX[TileCfgBB]`?
> > If call collectCfgCalls 2 times, the first time call will make sure at least 1 loop dependent BB status (can directly reach amx or not), So the 2nd can make sure all  BBs' status.
> But the 2nd call doesn't do anything. Since the first will add all BB into `BBVisited`, the 2nd call will return directly from line 251.
Oh, yes! I missed BBVisited.clear() before 2nd Call.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D95508/new/

https://reviews.llvm.org/D95508