1 files changed, 24 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp b/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
index f1048d9..cbb114f 100644
--- a/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
@@ -81,6 +81,7 @@ namespace {
     bool replaceIVUserWithLoopInvariant(Instruction *UseInst);
 
     bool eliminateOverflowIntrinsic(WithOverflowInst *WO);
+    bool eliminateSaturatingIntrinsic(SaturatingInst *SI);
     bool eliminateTrunc(TruncInst *TI);
     bool eliminateIVUser(Instruction *UseInst, Instruction *IVOperand);
     bool makeIVComparisonInvariant(ICmpInst *ICmp, Value *IVOperand);
@@ -477,6 +478,25 @@ bool SimplifyIndvar::eliminateOverflowIntrinsic(WithOverflowInst *WO) {
   return true;
 }
 
+bool SimplifyIndvar::eliminateSaturatingIntrinsic(SaturatingInst *SI) {
+  const SCEV *LHS = SE->getSCEV(SI->getLHS());
+  const SCEV *RHS = SE->getSCEV(SI->getRHS());
+  if (!willNotOverflow(SE, SI->getBinaryOp(), SI->isSigned(), LHS, RHS))
+    return false;
+
+  BinaryOperator *BO = BinaryOperator::Create(
+      SI->getBinaryOp(), SI->getLHS(), SI->getRHS(), SI->getName(), SI);
+  if (SI->isSigned())
+    BO->setHasNoSignedWrap();
+  else
+    BO->setHasNoUnsignedWrap();
+
+  SI->replaceAllUsesWith(BO);
+  DeadInsts.emplace_back(SI);
+  Changed = true;
+  return true;
+}
+
 bool SimplifyIndvar::eliminateTrunc(TruncInst *TI) {
   // It is always legal to replace
   //   icmp <pred> i32 trunc(iv), n
@@ -614,6 +634,10 @@ bool SimplifyIndvar::eliminateIVUser(Instruction *UseInst,
     if (eliminateOverflowIntrinsic(WO))
       return true;
 
+  if (auto *SI = dyn_cast<SaturatingInst>(UseInst))
+    if (eliminateSaturatingIntrinsic(SI))
+      return true;
+
   if (auto *TI = dyn_cast<TruncInst>(UseInst))
     if (eliminateTrunc(TI))
       return true;