[llvm] [VPlan] Don't rely on region check in isUniformAfterVectorization. (PR #137883)

[Florian Hahn via llvm-commits]

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@@ -39,18 +39,37 @@ const SCEV *getSCEVExprForVPValue(VPValue *V, ScalarEvolution &SE);
 
 /// Returns true if \p VPV is uniform after vectorization.
 inline bool isUniformAfterVectorization(const VPValue *VPV) {
+  auto IsKnownUniformOpcode = [](auto *R) -> bool {
+    return Instruction::isBinaryOp(R->getOpcode()) ||
+           Instruction::isCast(R->getOpcode()) ||
+           R->getOpcode() == Instruction::GetElementPtr ||
+           R->getOpcode() == Instruction::ICmp ||
+           R->getOpcode() == Instruction::FCmp;
+  };
+
   // A value defined outside the vector region must be uniform after
   // vectorization inside a vector region.
-  if (VPV->isDefinedOutsideLoopRegions())
+  if (VPV->isLiveIn())
     return true;
-  if (auto *Rep = dyn_cast<VPReplicateRecipe>(VPV))
-    return Rep->isUniform();
+  if (auto *Rep = dyn_cast<VPReplicateRecipe>(VPV)) {
+    const VPRegionBlock *ParentR = Rep->getParent()->getParent();
+    return Rep->isUniform() ||
+           (IsKnownUniformOpcode(Rep) &&
+            (!ParentR || !ParentR->isReplicator()) &&
+            all_of(Rep->operands(), isUniformAfterVectorization));
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fhahn wrote:

I moved the check out separately, although no uniform recipes should be in replicate regions

https://github.com/llvm/llvm-project/pull/137883