[llvm] [Mips] Fix cttz.i32 fails to lower on mips16 (PR #179633)

[Matt Arsenault via llvm-commits]

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@@ -9692,7 +9692,8 @@ SDValue TargetLowering::expandCTTZ(SDNode *Node, SelectionDAG &DAG) const {
   // Emit Table Lookup if ISD::CTPOP used in the fallback path below is going
   // to be expanded or converted to a libcall.
   if (!VT.isVector() && !isOperationLegalOrCustomOrPromote(ISD::CTPOP, VT) &&
-      !isOperationLegal(ISD::CTLZ, VT))
+      !isOperationLegal(ISD::CTLZ, VT) &&
+      isOperationCustom(ISD::ConstantPool, VT))
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arsenm wrote:

The code below isn't creating a constant pool,. It should check if the constant is legal 

https://github.com/llvm/llvm-project/pull/179633