[llvm] [RISCV] Use zext.[b/w/h] instead of th.extu for bitfieldn extraction (PR #101605)

[Craig Topper via llvm-commits]

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@@ -1228,6 +1228,10 @@ void RISCVDAGToDAGISel::Select(SDNode *Node) {
       if (!Subtarget->hasVendorXTHeadBb())
         return false;
 
+      if ((Subtarget->hasStdExtZba() || Subtarget->hasStdExtZbb()) &&
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topperc wrote:

Should we be checking bit 31 for hasStdExtZba and bit 7 and 15 for hasStdExtZbb?

https://github.com/llvm/llvm-project/pull/101605