1 files changed, 47 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index e4cb4574..07ad65c 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -5780,6 +5780,45 @@ Instruction *InstCombinerImpl::foldICmpWithMinMax(Instruction &I,
   return nullptr;
 }
 
+/// Match and fold patterns like:
+///   icmp eq/ne X, min(max(X, Lo), Hi)
+/// which represents a range check and can be repsented as a ConstantRange.
+///
+/// For icmp eq, build ConstantRange [Lo, Hi + 1) and convert to:
+///   (X - Lo) u< (Hi + 1 - Lo)
+/// For icmp ne, build ConstantRange [Hi + 1, Lo) and convert to:
+///   (X - (Hi + 1)) u< (Lo - (Hi + 1))
+Instruction *InstCombinerImpl::foldICmpWithClamp(ICmpInst &I, Value *X,
+                                                 MinMaxIntrinsic *Min) {
+  if (!I.isEquality() || !Min->hasOneUse() || !Min->isMin())
+    return nullptr;
+
+  const APInt *Lo = nullptr, *Hi = nullptr;
+  if (Min->isSigned()) {
+    if (!match(Min->getLHS(), m_OneUse(m_SMax(m_Specific(X), m_APInt(Lo)))) ||
+        !match(Min->getRHS(), m_APInt(Hi)) || !Lo->slt(*Hi))
+      return nullptr;
+  } else {
+    if (!match(Min->getLHS(), m_OneUse(m_UMax(m_Specific(X), m_APInt(Lo)))) ||
+        !match(Min->getRHS(), m_APInt(Hi)) || !Lo->ult(*Hi))
+      return nullptr;
+  }
+
+  ConstantRange CR = ConstantRange::getNonEmpty(*Lo, *Hi + 1);
+  ICmpInst::Predicate Pred;
+  APInt C, Offset;
+  if (I.getPredicate() == ICmpInst::ICMP_EQ)
+    CR.getEquivalentICmp(Pred, C, Offset);
+  else
+    CR.inverse().getEquivalentICmp(Pred, C, Offset);
+
+  if (!Offset.isZero())
+    X = Builder.CreateAdd(X, ConstantInt::get(X->getType(), Offset));
+
+  return replaceInstUsesWith(
+      I, Builder.CreateICmp(Pred, X, ConstantInt::get(X->getType(), C)));
+}
+
 // Canonicalize checking for a power-of-2-or-zero value:
 static Instruction *foldICmpPow2Test(ICmpInst &I,
                                      InstCombiner::BuilderTy &Builder) {
@@ -7467,10 +7506,14 @@ Instruction *InstCombinerImpl::foldICmpCommutative(CmpPredicate Pred,
     if (Instruction *NI = foldSelectICmp(Pred, SI, Op1, CxtI))
       return NI;
 
-  if (auto *MinMax = dyn_cast<MinMaxIntrinsic>(Op0))
+  if (auto *MinMax = dyn_cast<MinMaxIntrinsic>(Op0)) {
     if (Instruction *Res = foldICmpWithMinMax(CxtI, MinMax, Op1, Pred))
       return Res;
 
+    if (Instruction *Res = foldICmpWithClamp(CxtI, Op1, MinMax))
+      return Res;
+  }
+
   {
     Value *X;
     const APInt *C;
@@ -8527,6 +8570,9 @@ static Instruction *foldFCmpFSubIntoFCmp(FCmpInst &I, Instruction *LHSI,
             DenormalMode::getIEEE()) {
       CI.replaceOperand(I, 0, X);
       CI.replaceOperand(I, 1, Y);
+      I.setHasNoInfs(LHSI->hasNoInfs());
+      if (LHSI->hasNoNaNs())
+        I.setHasNoNaNs(true);
       return &I;
     }
     break;