Automerge: [SLP]Check if the first reduced value requires freeze/swap, if it may be too poisonous

If several reduced values are combined and the first reduced value is
just the original reduced value of the bool logical op, need to freeze
it to prevent the propagation of the poison value.

Fixes #114905

Author: alexey-bataev

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -19679,20 +19679,35 @@ class HorizontalReduction {
       return cast<Instruction>(ScalarCond);
     };
 
+    bool AnyBoolLogicOp = any_of(ReductionOps.back(), [](Value *V) {
+      return isBoolLogicOp(cast<Instruction>(V));
+    });
     // Return new VectorizedTree, based on previous value.
     auto GetNewVectorizedTree = [&](Value *VectorizedTree, Value *Res) {
       if (VectorizedTree) {
         // Update the final value in the reduction.
         Builder.SetCurrentDebugLocation(
             cast<Instruction>(ReductionOps.front().front())->getDebugLoc());
-        if ((isa<PoisonValue>(VectorizedTree) && !isa<PoisonValue>(Res)) ||
-            (isGuaranteedNotToBePoison(Res) &&
-             !isGuaranteedNotToBePoison(VectorizedTree))) {
-          auto It = ReducedValsToOps.find(Res);
-          if (It != ReducedValsToOps.end() &&
-              any_of(It->getSecond(),
-                     [](Instruction *I) { return isBoolLogicOp(I); }))
+        if (AnyBoolLogicOp) {
+
+          if (auto It = ReducedValsToOps.find(VectorizedTree);
+              It == ReducedValsToOps.end() ||
+              isGuaranteedNotToBePoison(VectorizedTree) ||
+              any_of(It->getSecond(), [&](Instruction *I) {
+                return isBoolLogicOp(I) &&
+                       getRdxOperand(I, 0) == VectorizedTree;
+              })) {
+            ;
+          } else if (auto It = ReducedValsToOps.find(Res);
+                     It == ReducedValsToOps.end() ||
+                     isGuaranteedNotToBePoison(Res) ||
+                     any_of(It->getSecond(), [&](Instruction *I) {
+                       return isBoolLogicOp(I) && getRdxOperand(I, 0) == Res;
+                     })) {
             std::swap(VectorizedTree, Res);
+          } else {
+            VectorizedTree = Builder.CreateFreeze(VectorizedTree);
+          }
         }
 
         return createOp(Builder, RdxKind, VectorizedTree, Res, "op.rdx",
@@ -19701,9 +19716,6 @@ class HorizontalReduction {
       // Initialize the final value in the reduction.
       return Res;
     };
-    bool AnyBoolLogicOp = any_of(ReductionOps.back(), [](Value *V) {
-      return isBoolLogicOp(cast<Instruction>(V));
-    });
     SmallDenseSet<Value *> IgnoreList(ReductionOps.size() *
                                       ReductionOps.front().size());
     for (ReductionOpsType &RdxOps : ReductionOps)

llvm/test/Transforms/SLPVectorizer/logical-ops-poisonous-repeated.ll

@@ -12,7 +12,8 @@ define i1 @test(<4 x i32> %x) {
 ; CHECK-NEXT:    [[C1:%.*]] = icmp slt i32 [[X1]], 0
 ; CHECK-NEXT:    [[C2:%.*]] = icmp sgt i32 [[X2]], 0
 ; CHECK-NEXT:    [[C3:%.*]] = icmp slt i32 [[X3]], 0
-; CHECK-NEXT:    [[OP_RDX:%.*]] = select i1 [[C3]], i1 [[C1]], i1 false
+; CHECK-NEXT:    [[TMP2:%.*]] = freeze i1 [[C3]]
+; CHECK-NEXT:    [[OP_RDX:%.*]] = select i1 [[TMP2]], i1 [[C1]], i1 false
 ; CHECK-NEXT:    [[OP_RDX1:%.*]] = select i1 [[OP_RDX]], i1 [[TMP1]], i1 false
 ; CHECK-NEXT:    ret i1 [[OP_RDX1]]
 ;