[clang-tools-extra] [llvm] [Matrix] Convert column-vector ops feeding dot product to row-vectors. (PR #72647)

[Visoiu Mistrih Francis via cfe-commits]

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@@ -1391,7 +1394,26 @@ class LowerMatrixIntrinsics {
       return TTI.getMemoryOpCost(Instruction::Load, VecTy, Align(1), 0) -
              N * TTI.getMemoryOpCost(Instruction::Load, EltTy, Align(1), 0);
     };
-    auto LHSCost = GetCostForArg(LHS, LShape.NumColumns);
+
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francisvm wrote:

It's been a while since I looked at how you determine the cost for dot products. Do you mind adding a comment with a summary or explaining it here?

https://github.com/llvm/llvm-project/pull/72647