[llvm] [X86] combineBROADCAST_LOAD - merge across chains (PR #128209)

[Simon Pilgrim via llvm-commits]

================
@@ -59322,21 +59322,14 @@ static SDValue combineFP_EXTEND(SDNode *N, SelectionDAG &DAG,
   return DAG.getNode(ISD::FP_EXTEND, dl, VT, Cvt);
 }
 
-// Try to find a larger VBROADCAST_LOAD/SUBV_BROADCAST_LOAD that we can extract
-// from. Limit this to cases where the loads have the same input chain and the
-// output chains are unused. This avoids any memory ordering issues.
+// Try to find a larger VBROADCAST_LOAD/SUBV_BROADCAST_LOAD that we can extract.
----------------
RKSimon wrote:

We should only create broadcast load nodes if they're simple. But I'll add an assert to be sure.

https://github.com/llvm/llvm-project/pull/128209