[TargetLowering][NFC] prepareUREMEqFold(): fixup comment

LebedevRI · LebedevRI · commit f4de7eda4a70 · 2019-08-13T14:57:08.000Z
The comment initially matched the code, but the code was incorrect
and was fixed after the initial revert back back when it was introduced,
but the comment was never updated.

llvm-svn: 368701
diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -4866,7 +4866,7 @@ TargetLowering::prepareUREMEqFold(EVT SETCCVT, SDValue REMNode,
   // fold (seteq/ne (urem N, D), 0) -> (setule/ugt (rotr (mul N, P), K), Q)
   // - D must be constant, with D = D0 * 2^K where D0 is odd
   // - P is the multiplicative inverse of D0 modulo 2^W
-  // - Q = floor((2^W - 1) / D0)
+  // - Q = floor(((2^W) - 1) / D)
   // where W is the width of the common type of N and D.
   assert((Cond == ISD::SETEQ || Cond == ISD::SETNE) &&
          "Only applicable for (in)equality comparisons.");
