Hardcode allow hoist of readfirstlane on MI350

Change-Id: I62cc4257f759d1bc8ad2bc0bc1812bb63794a325

Author: jrbyrnes

llvm/lib/Transforms/Scalar/LICM.cpp

@@ -1163,6 +1163,9 @@ bool llvm::canSinkOrHoistInst(Instruction &I, AAResults *AA, DominatorTree *DT,
                               SinkAndHoistLICMFlags &Flags,
                               OptimizationRemarkEmitter *ORE) {
   // If we don't understand the instruction, bail early.
+  if (auto II = dyn_cast<IntrinsicInst>(&I)) {
+    return II->getIntrinsicID() == 3036;
+  }
   if (!isHoistableAndSinkableInst(I))
     return false;