[llvm] [InstCombine] Push freeze through non-recurrence PHIs (PR #157678)

[Cullen Rhodes via llvm-commits]

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@@ -5042,10 +5042,18 @@ InstCombinerImpl::pushFreezeToPreventPoisonFromPropagating(FreezeInst &OrigFI) {
   //   Op1.fr = Freeze(Op1)
   //   ... = Inst(Op1.fr, NonPoisonOps...)
 
-  auto CanPushFreeze = [](Value *V) {
-    if (!isa<Instruction>(V) || isa<PHINode>(V))
+  auto CanPushFreeze = [this](Value *V) {
+    if (!isa<Instruction>(V))
       return false;
 
+    if (auto *PN = dyn_cast<PHINode>(V)) {
+      if (llvm::any_of(PN->incoming_values(), [this, &PN](Use &U) {
+            return DT.dominates(PN->getParent(), PN->getIncomingBlock(U)) ||
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c-rhodes wrote:

added a check for `isBackEdge()`. Although unlike the other edge cases you pointed out I couldn't write a test case that triggered an issue for this one.

https://github.com/llvm/llvm-project/pull/157678