[llvm] [VPlan] Introduce explicit broadcasts for live-ins. (PR #124644)

[Florian Hahn via llvm-commits]

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@@ -3716,6 +3759,9 @@ class VPlan {
   /// Return the live-in VPValue for \p V, if there is one or nullptr otherwise.
   VPValue *getLiveIn(Value *V) const { return Value2VPValue.lookup(V); }
 
+  /// Return the list of live-in VPValues available in the VPlan.
+  ArrayRef<VPValue *> getLiveIns() const { return VPLiveIns; }
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fhahn wrote:

Thanks, I added an assert to `getLiveIns()` to make sure all VPValues also in `Value2VPValue` are included in `VPLiveIns` . At the moment that's guaranteed, as `getOrAddLiveIn` is the only place that adds to  `Value2VPValue` and `VPLiveIns`. Live-ins are only destroyed when the VPlan is destroyed, so at the moment nothing should remove from either `VPLiveIns` or `Value2VPValue` .

I left the name of `getLiveIn` unchanged for now here as that should probably done separately, although the `ForValue` part is implied by the argument type. WDYT?

https://github.com/llvm/llvm-project/pull/124644