[PATCH] D93594: [X86] Pass to transform amx intrinsics to scalar operation.

[Pengfei Wang via Phabricator via cfe-commits]

pengfei added inline comments.


================
Comment at: llvm/lib/Target/X86/X86LowerAMXIntrinsics.cpp:311
+  Value *ResElt = B.CreateAdd(EltC, SubVecR);
+  Value *NewVecC = B.CreateInsertElement(VecCPhi, ResElt, IdxC);
+  Value *NewVecD = B.CreateInsertElement(VecDPhi, ResElt, IdxC);
----------------
yubing wrote:
> pengfei wrote:
> > Is it necessary to insert the ResElt to VecC?
> Yes, it is necessary since you should use updated eltC(aka, Cij) when you are doing matrix dotproduct:
> Cij =Cij+Ai1.*B1j
> Cij =Cij+Ai2.*B2j
> ....
> Cij =Cij+AiK.*BKj
But you don't need to update both C and D. Something like the psudo code should enough:
```
for (k : K)
  Dij += Aik * Bkj;
Dij += Cij
```


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D93594/new/

https://reviews.llvm.org/D93594