[llvm] [KnownBits] Mark constructor for KnownBits as explicit (PR #190253)

[Max Graey via llvm-commits]

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@@ -7673,7 +7673,7 @@ static void computeKnownBitsForPRMT(const SDValue Op, KnownBits &Known,
     unsigned Sign = Sel.getHiBits(1).getZExtValue();
     KnownBits Byte = BitField.extractBits(8, Idx * 8);
     if (Sign)
-      Byte = KnownBits::ashr(Byte, 8);
+      Byte = KnownBits::ashr(Byte, KnownBits(8));
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MaxGraey wrote:

Moreover, since this is sign propagation, it should look like this: `KnownBits::makeConstant(APInt(8, 7))`. And since this is more accurate, we may have to update some lit tests for NVPX

https://github.com/llvm/llvm-project/pull/190253