[llvm] [VPlan] Add ExtractLane VPInst to extract across multiple parts. (PR #148817)

[Luke Lau via llvm-commits]

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@@ -1067,6 +1095,7 @@ bool VPInstruction::onlyFirstLaneUsed(const VPValue *Op) const {
   default:
     return false;
   case Instruction::ExtractElement:
+  case VPInstruction::ExtractLane:
     return Op == getOperand(1);
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lukel97 wrote:

Should this be checking `getOperand(0)`?

https://github.com/llvm/llvm-project/pull/148817