[llvm] [VPlan] Recursively match operands of interleave group (PR #164839)

[Ramkumar Ramachandra via llvm-commits]

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@@ -4108,25 +4116,51 @@ VPlanTransforms::expandSCEVs(VPlan &Plan, ScalarEvolution &SE) {
   return ExpandedSCEVs;
 }
 
-/// Returns true if \p V is VPWidenLoadRecipe or VPInterleaveRecipe that can be
-/// converted to a narrower recipe. \p V is used by a wide recipe that feeds a
-/// store interleave group at index \p Idx, \p WideMember0 is the recipe feeding
-/// the same interleave group at index 0. A VPWidenLoadRecipe can be narrowed to
-/// an index-independent load if it feeds all wide ops at all indices (\p OpV
-/// must be the operand at index \p OpIdx for both the recipe at lane 0, \p
-/// WideMember0). A VPInterleaveRecipe can be narrowed to a wide load, if \p V
-/// is defined at \p Idx of a load interleave group.
-static bool canNarrowLoad(VPWidenRecipe *WideMember0, unsigned OpIdx,
-                          VPValue *OpV, unsigned Idx) {
-  auto *DefR = OpV->getDefiningRecipe();
-  if (!DefR)
-    return WideMember0->getOperand(OpIdx) == OpV;
-  if (auto *W = dyn_cast<VPWidenLoadRecipe>(DefR))
-    return !W->getMask() && WideMember0->getOperand(OpIdx) == OpV;
-
-  if (auto *IR = dyn_cast<VPInterleaveRecipe>(DefR))
-    return IR->getInterleaveGroup()->isFull() && IR->getVPValue(Idx) == OpV;
-  return false;
+/// Returns true if the \p StoredValues of an interleave group match. It does
+/// this by going through operands recursively until it hits the leaf cases:
+/// VPWidenLoadRecipe, VPInterleaveRecipe, and live-ins.
+static bool interleaveStoredValuesMatch(ArrayRef<VPValue *> StoredValues) {
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artagnon wrote:

Yes, I totally endorse your approach: I think I made a mess of this patch by trying to do too much.

https://github.com/llvm/llvm-project/pull/164839