[llvm] Update the base and index value for masked gather (PR #130920)

[Matt Arsenault via llvm-commits]

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@@ -5127,6 +5127,13 @@ class TargetLowering : public TargetLoweringBase {
                                               SmallVectorImpl<SDValue> &Ops,
                                               SelectionDAG &DAG) const;
 
+  // Target may override this function to decided whether it want to update the
+  // base and index value of a non-uniform gep
+  virtual bool updateBaseAndIndex(const Value *Ptr, SDValue &Base,
+                                  SDValue &Index, const SDLoc &DL,
+                                  const SDValue &Gep, SelectionDAG &DAG,
+                                  const BasicBlock *CurBB) const;
+
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arsenm wrote:

Name and purpose unclear. We also have way too many poorly designed, narrow purpose hooks. You should try to avoid introducing this without a very strong justification for why there can't be a reasonable default behavior.

https://github.com/llvm/llvm-project/pull/130920