2 files changed, 17 insertions, 58 deletions

diff --git a/contrib/llvm-project/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp b/contrib/llvm-project/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
index a1d7f0f9ba0f..a3951fdf8a15 100644
--- a/contrib/llvm-project/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
+++ b/contrib/llvm-project/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
@@ -1366,61 +1366,6 @@ 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;
-
-    // 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) {
@@ -1448,7 +1393,7 @@ 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();
   }
diff --git a/contrib/llvm-project/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp b/contrib/llvm-project/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
index 0ed3324a27b6..1b142f14d811 100644
--- a/contrib/llvm-project/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
+++ b/contrib/llvm-project/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
@@ -16,6 +16,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/ValueTracking.h"
 #include "llvm/IR/Dominators.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/Instructions.h"
@@ -713,8 +714,11 @@ bool SimplifyIndvar::replaceFloatIVWithIntegerIV(Instruction *UseInst) {
 bool SimplifyIndvar::eliminateIdentitySCEV(Instruction *UseInst,
                                            Instruction *IVOperand) {
   if (!SE->isSCEVable(UseInst->getType()) ||
-      (UseInst->getType() != IVOperand->getType()) ||
-      (SE->getSCEV(UseInst) != SE->getSCEV(IVOperand)))
+      UseInst->getType() != IVOperand->getType())
+    return false;
+
+  const SCEV *UseSCEV = SE->getSCEV(UseInst);
+  if (UseSCEV != SE->getSCEV(IVOperand))
     return false;
 
   // getSCEV(X) == getSCEV(Y) does not guarantee that X and Y are related in the
@@ -742,6 +746,16 @@ bool SimplifyIndvar::eliminateIdentitySCEV(Instruction *UseInst,
   if (!LI->replacementPreservesLCSSAForm(UseInst, IVOperand))
     return false;
 
+  // Make sure the operand is not more poisonous than the instruction.
+  if (!impliesPoison(IVOperand, UseInst)) {
+    SmallVector<Instruction *> DropPoisonGeneratingInsts;
+    if (!SE->canReuseInstruction(UseSCEV, IVOperand, DropPoisonGeneratingInsts))
+      return false;
+
+    for (Instruction *I : DropPoisonGeneratingInsts)
+      I->dropPoisonGeneratingFlagsAndMetadata();
+  }
+
   LLVM_DEBUG(dbgs() << "INDVARS: Eliminated identity: " << *UseInst << '\n');
 
   SE->forgetValue(UseInst);