[llvm] [LV] Autovectorization for the all-in-one histogram intrinsic (PR #91458)

[Paschalis Mpeis via llvm-commits]

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@@ -8406,6 +8416,34 @@ VPWidenRecipe *VPRecipeBuilder::tryToWiden(Instruction *I,
   };
 }
 
+VPHistogramRecipe *
+VPRecipeBuilder::tryToWidenHistogram(const HistogramInfo *HI,
+                                     ArrayRef<VPValue *> Operands) {
+  // FIXME: Support other operations.
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paschalis-mpeis wrote:

There seems to be some partial support for 'sub' in other places? ie
- in `AccessAnalysis::findHistograms`, and
- in `LoopVectorizationCostModel::getInstructionCost`

https://github.com/llvm/llvm-project/pull/91458