[SCEV] Move canReuseInstruction() helper into SCEV (NFC)

To allow reusing it in IndVars.

1 files changed, 1 insertions, 63 deletions

diff --git a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp b/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
index 34597e6..58dbac0 100644
--- a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
+++ b/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
@@ -1363,68 +1363,6 @@ Value *SCEVExpander::expandCodeFor(const SCEV *SH, Type *Ty) {
   return V;
 }
 
-static bool
-canReuseInstruction(ScalarEvolution &SE, const SCEV *S, Instruction *I,
-                    SmallVectorImpl<Instruction *> &DropPoisonGeneratingInsts) {
-  // If the instruction cannot be poison, it's always safe to reuse.
-  if (programUndefinedIfPoison(I))
-    return true;
-
-  // Otherwise, it is possible that I is more poisonous that S. Collect the
-  // poison-contributors of S, and then check whether I has any additional
-  // poison-contributors. Poison that is contributed through poison-generating
-  // flags is handled by dropping those flags instead.
-  SmallPtrSet<const Value *, 8> PoisonVals;
-  SE.getPoisonGeneratingValues(PoisonVals, S);
-
-  SmallVector<Value *> Worklist;
-  SmallPtrSet<Value *, 8> Visited;
-  Worklist.push_back(I);
-  while (!Worklist.empty()) {
-    Value *V = Worklist.pop_back_val();
-    if (!Visited.insert(V).second)
-      continue;
-
-    // Avoid walking large instruction graphs.
-    if (Visited.size() > 16)
-      return false;
-
-    // Either the value can't be poison, or the S would also be poison if it
-    // is.
-    if (PoisonVals.contains(V) || isGuaranteedNotToBePoison(V))
-      continue;
-
-    auto *I = dyn_cast<Instruction>(V);
-    if (!I)
-      return false;
-
-    // Disjoint or instructions are interpreted as adds by SCEV. However, we
-    // can't replace an arbitrary add with disjoint or, even if we drop the
-    // flag. We would need to convert the or into an add.
-    if (auto *PDI = dyn_cast<PossiblyDisjointInst>(I))
-      if (PDI->isDisjoint())
-        return false;
-
-    // FIXME: Ignore vscale, even though it technically could be poison. Do this
-    // because SCEV currently assumes it can't be poison. Remove this special
-    // case once we proper model when vscale can be poison.
-    if (auto *II = dyn_cast<IntrinsicInst>(I);
-        II && II->getIntrinsicID() == Intrinsic::vscale)
-      continue;
-
-    if (canCreatePoison(cast<Operator>(I), /*ConsiderFlagsAndMetadata*/ false))
-      return false;
-
-    // If the instruction can't create poison, we can recurse to its operands.
-    if (I->hasPoisonGeneratingFlagsOrMetadata())
-      DropPoisonGeneratingInsts.push_back(I);
-
-    for (Value *Op : I->operands())
-      Worklist.push_back(Op);
-  }
-  return true;
-}
-
 Value *SCEVExpander::FindValueInExprValueMap(
     const SCEV *S, const Instruction *InsertPt,
     SmallVectorImpl<Instruction *> &DropPoisonGeneratingInsts) {
@@ -1452,7 +1390,7 @@ Value *SCEVExpander::FindValueInExprValueMap(
       continue;
 
     // Make sure reusing the instruction is poison-safe.
-    if (canReuseInstruction(SE, S, EntInst, DropPoisonGeneratingInsts))
+    if (SE.canReuseInstruction(S, EntInst, DropPoisonGeneratingInsts))
       return V;
     DropPoisonGeneratingInsts.clear();
   }