[llvm] [GISel][CombinerHelper] Push freeze through non-poison-producing operands (PR #90618)

[Matt Arsenault via llvm-commits]

================
@@ -1733,10 +1733,21 @@ static bool canCreateUndefOrPoison(Register Reg, const MachineRegisterInfo &MRI,
                                    UndefPoisonKind Kind) {
   MachineInstr *RegDef = MRI.getVRegDef(Reg);
 
+  if (auto *GMI = dyn_cast<GenericMachineInstr>(RegDef)) {
+    if (ConsiderFlagsAndMetadata && includesPoison(Kind) &&
+        GMI->hasPoisonGeneratingFlags())
+      return true;
+  }
+  // Conservatively return true.
----------------
arsenm wrote:

Weird comment placement, move with the actual case  with braces 

https://github.com/llvm/llvm-project/pull/90618