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

[Sam Tebbs via llvm-commits]

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@@ -8687,9 +8794,14 @@ VPRecipeBuilder::tryToCreateWidenRecipe(Instruction *Instr,
           Legal->getReductionVars().find(Phi)->second;
       assert(RdxDesc.getRecurrenceStartValue() ==
              Phi->getIncomingValueForBlock(OrigLoop->getLoopPreheader()));
-      PhiRecipe = new VPReductionPHIRecipe(Phi, RdxDesc, *StartV,
-                                           CM.isInLoopReduction(Phi),
-                                           CM.useOrderedReductions(RdxDesc));
+
+      // If the PHI is used by a partial reduction, set the scale factor
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SamTebbs33 wrote:

Ah yes, sorry, definitely done now.

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