[llvm] [LoopVectorizer] Add support for partial reductions (PR #92418)

[Sam Tebbs via llvm-commits]

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@@ -6995,7 +7122,17 @@ LoopVectorizationPlanner::planInVPlanNativePath(ElementCount UserVF) {
 
 void LoopVectorizationPlanner::plan(ElementCount UserVF, unsigned UserIC) {
   assert(OrigLoop->isInnermost() && "Inner loop expected.");
-  CM.collectValuesToIgnore();
+
+  for (auto ReductionVar : Legal->getReductionVars()) {
+    auto *ReductionExitInstr = ReductionVar.second.getLoopExitInstr();
+    if (isInstrPartialReduction(ReductionExitInstr)) {
+      auto Chain = getPartialReductionInstrChain(ReductionExitInstr);
+      if (isPartialReductionChainValid(Chain, TTI))
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SamTebbs33 wrote:

Done. Please let me know if it's as you expected.

https://github.com/llvm/llvm-project/pull/92418