[PATCH] D68360: PR41162 Implement LKK remainder and divisibility algorithms

[Tim Gymnich via Phabricator via llvm-commits]

TG908 marked 2 inline comments as done.
TG908 added inline comments.


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Comment at: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:3975
+  } else {
+    FVT = EVT::getIntegerVT(*DAG.getContext(), VT.getScalarSizeInBits() * 2);
+  }
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lebedev.ri wrote:
> So no 64-bit remainders on basically everything?
According to the paper a good choice for the number of fraction bits would be twice the number of numerator bits. This limits us on 64bit platforms to 32bit rem only.


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Comment at: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:3990-3991
+  // If MUL is unavailable, we cannot proceed in any case.
+  if (!TLI.isOperationLegalOrCustomOrPromote(ISD::MUL, FVT) &&
+      TLI.isOperationExpand(ISD::MUL, FVT))
+    return SDValue();
----------------
lebedev.ri wrote:
> I think you want just `isOperationLegalOrCustom()`.
agree


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https://reviews.llvm.org/D68360