[llvm] [clang-tools-extra] [flang] [mlir] [libcxx] [clang] [LV] Improve AnyOf reduction codegen. (PR #78304)

[via cfe-commits]

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@@ -9110,6 +9111,41 @@ void LoopVectorizationPlanner::adjustRecipesForReductions(
       continue;
 
     const RecurrenceDescriptor &RdxDesc = PhiR->getRecurrenceDescriptor();
+    // Adjust AnyOf reductions; replace the reduction phi for the selected value
+    // with a boolean reduction phi node to check if the condition is true in
+    // any iteration. The final value is selected by the final
+    // ComputeReductionResult.
+    if (RecurrenceDescriptor::isAnyOfRecurrenceKind(
+            RdxDesc.getRecurrenceKind())) {
+      auto *Select = cast<VPRecipeBase>(*find_if(PhiR->users(), [](VPUser *U) {
+        return isa<VPWidenSelectRecipe>(U) ||
+               (isa<VPReplicateRecipe>(U) &&
+                cast<VPReplicateRecipe>(U)->getUnderlyingInstr()->getOpcode() ==
+                    Instruction::Select);
+      }));
+      VPValue *Cmp = Select->getOperand(0);
+      // If the compare is checking the reduction PHI node, adjust it to check
+      // the start value.
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ayalz wrote:

Hmm, either the true or false values of the select should use PhiR, but only it? The condition of an AnyOf reduction should be any boolean-expression predicate that depends on the current iteration only, i.e., should be a recipe (if it's live-in the entire select should be LICM'd), independent of AnyOf's PhiR, neither directly nor indirectly?

https://github.com/llvm/llvm-project/pull/78304