[llvm] [CodeGen] Expand unsupported interleave to shuffles (PR #210494)

[Simon Pilgrim via llvm-commits]

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@@ -3324,6 +3324,13 @@ class LLVM_ABI TargetLoweringBase {
   /// Default to be the minimum interleave factor: 2.
   virtual unsigned getMaxSupportedInterleaveFactor() const { return 2; }
 
+  /// Return true if the target supports interleave intrinsic for the specified
+  /// factor and vector type.
+  virtual bool isInterleaveIntrinsicSupported(unsigned /*Factor*/,
+                                              EVT /*VecTy*/) const {
+    return false;
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RKSimon wrote:

why isn't this a TLI.isOperationLegalOrCustom check instead of a target hook?

https://github.com/llvm/llvm-project/pull/210494