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

[Florian Hahn via flang-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.
+      if (VPRecipeBase *CmpR = Cmp->getDefiningRecipe()) {
+        for (unsigned I = 0; I != CmpR->getNumOperands(); ++I)
+          if (CmpR->getOperand(I) == PhiR)
+            CmpR->setOperand(I, PhiR->getStartValue());
+      }
+      VPBuilder::InsertPointGuard Guard(Builder);
+      Builder.setInsertPoint(Select);
+
+      // If the true value of the select is the reduction phi, the new value is
+      // selected if the negated condition is true in any iteration.
+      if (Select->getOperand(1) == PhiR)
+        Cmp = Builder.createNot(Cmp);
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fhahn wrote:

Yes, this could be handled like that, but I think then we would need to support both patterns here and also in codegen, so negating seems simpler (and the negation should be removable by instcombine). Left as is for now, but happy to adjust if needed. But then it should probably be modeled as AllOf directly in the reduction descriptor.

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