[llvm] [LV] Convert scatter w/uniform addr and mask being header mask to scalar store. (PR #172799)

[Elvis Wang via llvm-commits]

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@@ -1602,6 +1602,90 @@ void VPlanTransforms::simplifyRecipes(VPlan &Plan) {
   }
 }
 
+void VPlanTransforms::narrowScatters(VPlan &Plan, VPCostContext &Ctx,
+                                     VFRange &Range,
+                                     const bool &FoldTailWithEVL) {
+  if (Plan.hasScalarVFOnly())
+    return;
+
+  for (VPBasicBlock *VPBB : VPBlockUtils::blocksOnly<VPBasicBlock>(
+           vp_depth_first_shallow(Plan.getVectorLoopRegion()->getEntry()))) {
+    for (VPRecipeBase &R : make_early_inc_range(reverse(*VPBB))) {
+      if (!isa<VPWidenStoreRecipe>(&R))
+        continue;
+      // Convert an unmasked or header masked scatter with an uniform address
+      // into extract-last-lane + scalar store.
+      // TODO: Add a profitability check comparing the cost of a scatter vs.
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ElvisWang123 wrote:

Removed, thanks!

https://github.com/llvm/llvm-project/pull/172799