[llvm] [LICM] Allow hoisting of InsertElementInst's past non-hoistable InsertElementInsts (PR #200532)

[Luke Lau via llvm-commits]

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@@ -1058,6 +1074,87 @@ bool llvm::hoistRegion(DomTreeNode *N, AAResults *AA, LoopInfo *LI,
   return Changed;
 }
 
+static bool hoistInsertPastInsert(
+    InsertElementInst *Ins, Loop *CurLoop, AAResults *AA, DominatorTree *DT,
+    const TargetLibraryInfo *TLI, BasicBlock *Preheader, BasicBlock *HoistDest,
+    ICFLoopSafetyInfo *SafetyInfo, MemorySSAUpdater &MSSAU, AssumptionCache *AC,
+    ScalarEvolution *SE, SinkAndHoistLICMFlags &Flags,
+    OptimizationRemarkEmitter *ORE,
+    SmallVectorImpl<Instruction *> &HoistedInstructions,
+    bool AllowSpeculation) {
+  SmallSet<uint64_t, 4> SeenIndexes;
+  InsertElementInst *Inner;
+  auto CanBypass = [&](auto &CanBypass, InsertElementInst *CurrIns,
+                       bool IsHoistedInstruction) -> bool {
+    // Instruction being hoisted past must only have one use
+    if (!IsHoistedInstruction && !CurrIns->hasOneUse())
+      return false;
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lukel97 wrote:

Instead of threading through a bool, can we just move this check down to before the recursive call on line 1123?

https://github.com/llvm/llvm-project/pull/200532