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

[Matt Arsenault via llvm-commits]

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@@ -34,6 +34,22 @@ class GenericMachineInstr : public MachineInstr {
   static bool classof(const MachineInstr *MI) {
     return isPreISelGenericOpcode(MI->getOpcode());
   }
+
+  bool hasPoisonGeneratingFlags() const {
+    return getFlags() & (NoUWrap | NoSWrap | IsExact | Disjoint | NonNeg |
+                         FmNoNans | FmNoInfs);
+  }
+
+  void dropPoisonGeneratingFlags() {
+    clearFlag(NoUWrap);
+    clearFlag(NoSWrap);
+    clearFlag(IsExact);
+    clearFlag(Disjoint);
+    clearFlag(NonNeg);
+    clearFlag(FmNoNans);
+    clearFlag(FmNoInfs);
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arsenm wrote:

Should be able to do this at once as well 

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