Made suggested changes but couldn't generalize to div/rem as suggested

"If it is the case, you should generalize it to handle most of binops (excluding div/rem), then use simplifyBinOp and simplifyBinaryIntrinsic to check if min/max(c1 binop c2, c3) folds to c3."

Author: Charukesh827

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

@@ -1172,75 +1172,75 @@ static Instruction *moveAddAfterMinMax(IntrinsicInst *II,
                   : BinaryOperator::CreateNUWAdd(NewMinMax, Add->getOperand(1));
 }
 
-//Try canonicalize min/max(x << shamt, c<<shamt) into max(x, c) << shamt
-static Instruction *moveShiftAfterMinMax(IntrinsicInst *II, InstCombiner::BuilderTy &Builder) {
+// Try canonicalize max(max(X,C1) binop C2, C3) -> max(X binop C2, C3)
+static Instruction *moveShiftAfterMinMax(IntrinsicInst *II,
+                                         InstCombiner::BuilderTy &Builder) {
   Intrinsic::ID MinMaxID = II->getIntrinsicID();
-  assert((MinMaxID == Intrinsic::smax || MinMaxID == Intrinsic::smin ||
-    MinMaxID == Intrinsic::umax || MinMaxID == Intrinsic::umin) &&
-   "Expected a min or max intrinsic");
-  
+  assert(isa<MinMaxIntrinsic>(II) &&
+         "Expected a min or max intrinsic");
+
   Value *Op0 = II->getArgOperand(0), *Op1 = II->getArgOperand(1);
   Value *InnerMax;
   const APInt *C;
-  if (!match(Op0, m_OneUse(m_BinOp(m_Value(InnerMax), m_APInt(C)))) || 
+  if (!match(Op0, m_OneUse(m_BinOp(m_Value(InnerMax), m_APInt(C)))) ||
       !match(Op1, m_APInt(C)))
-      return nullptr;
-  
-  auto* BinOpInst = cast<BinaryOperator>(Op0);
+    return nullptr;
+    
+  auto *BinOpInst = cast<BinaryOperator>(Op0);
   Instruction::BinaryOps BinOp = BinOpInst->getOpcode();
-  Value *X;
+
   InnerMax = BinOpInst->getOperand(0);
-  // std::cout<< InnerMax->dump() <<std::endl;
-  if(!match(InnerMax,m_OneUse(m_Intrinsic<Intrinsic::umax>(m_Value(X),m_APInt(C))))){
-  if(!match(InnerMax,m_OneUse(m_Intrinsic<Intrinsic::smax>(m_Value(X),m_APInt(C))))){
-  if(!match(InnerMax,m_OneUse(m_Intrinsic<Intrinsic::umin>(m_Value(X),m_APInt(C))))){
-  if(!match(InnerMax,m_OneUse(m_Intrinsic<Intrinsic::smin>(m_Value(X),m_APInt(C))))){
-     return nullptr;
-  }}}}
-  
-  auto *InnerMaxInst = cast<IntrinsicInst>(InnerMax);
 
-  bool IsSigned = MinMaxID == Intrinsic::smax || MinMaxID == Intrinsic::smin;
-  if((IsSigned && !BinOpInst->hasNoSignedWrap()) ||
-     (!IsSigned && !BinOpInst->hasNoUnsignedWrap())) 
-     return nullptr;
+  auto *InnerMinMaxInst = dyn_cast<MinMaxIntrinsic>(BinOpInst->getOperand(0));
+
+  if (!InnerMinMaxInst || !InnerMinMaxInst->hasOneUse()) 
+    return nullptr;
+
+  bool IsSigned = InnerMinMaxInst->isSigned();
+  if (InnerMinMaxInst->getIntrinsicID() != MinMaxID)
+    return nullptr;
+
+  if ((IsSigned && !BinOpInst->hasNoSignedWrap()) ||
+      (!IsSigned && !BinOpInst->hasNoUnsignedWrap()))
+    return nullptr;
 
   // Check if BinOp is a left shift
   if (BinOp != Instruction::Shl) {
     return nullptr;
   }
 
-  APInt C2=llvm::dyn_cast<llvm::ConstantInt>(BinOpInst->getOperand(1))->getValue() ;
-  APInt C3=llvm::dyn_cast<llvm::ConstantInt>(II->getArgOperand(1))->getValue();
-  APInt C1=llvm::dyn_cast<llvm::ConstantInt>(InnerMaxInst->getOperand(1))->getValue();
+  APInt C2 =llvm::dyn_cast<llvm::ConstantInt>(BinOpInst->getOperand(1))->getValue();
+  APInt C3 =llvm::dyn_cast<llvm::ConstantInt>(II->getArgOperand(1))->getValue();
+  APInt C1 = llvm::dyn_cast<llvm::ConstantInt>(InnerMinMaxInst->getOperand(1))->getValue();
 
   // Compute C1 * 2^C2
   APInt Two = APInt(C2.getBitWidth(), 2);
-  APInt Pow2C2 = Two.shl(C2); // 2^C2
+  APInt Pow2C2 = Two.shl(C2);        // 2^C2
   APInt C1TimesPow2C2 = C1 * Pow2C2; // C1 * 2^C2
 
   // Check C3 >= C1 * 2^C2
   if (C3.ult(C1TimesPow2C2)) {
     return nullptr;
   }
 
-  //Create new x binop c2
-  Value *NewBinOp = Builder.CreateBinOp(BinOp, InnerMaxInst->getOperand(0), BinOpInst->getOperand(1) );
-  
-  //Create new min/max intrinsic with new binop and c3
-  
-    if(IsSigned){
-      cast<Instruction>(NewBinOp) -> setHasNoSignedWrap(true);
-      cast<Instruction>(NewBinOp) -> setHasNoUnsignedWrap(false);
-    }else{
-      cast<Instruction>(NewBinOp) -> setHasNoUnsignedWrap(true);
-      cast<Instruction>(NewBinOp) -> setHasNoSignedWrap(false);
+  // Create new x binop c2
+  Value *NewBinOp = Builder.CreateBinOp(BinOp, InnerMinMaxInst->getOperand(0),
+                                        BinOpInst->getOperand(1));
+
+  // Create new min/max intrinsic with new binop and c3
+  if (auto *NewBinInst = dyn_cast<Instruction>(NewBinOp))
+    if (IsSigned) {
+      cast<Instruction>(NewBinOp)->setHasNoSignedWrap(true);
+      cast<Instruction>(NewBinOp)->setHasNoUnsignedWrap(false);
+    } else {
+      cast<Instruction>(NewBinOp)->setHasNoUnsignedWrap(true);
+      cast<Instruction>(NewBinOp)->setHasNoSignedWrap(false);
     }
-  
 
   // Get the intrinsic function for MinMaxID
   Type *Ty = II->getType();
-  Function *MinMaxFn = Intrinsic::getDeclaration(II->getModule(), MinMaxID, {Ty});
+  Function *MinMaxFn =
+      Intrinsic::getDeclaration(II->getModule(), MinMaxID, {Ty});
 
   // Create new min/max intrinsic: MinMaxID(NewBinOp, C3) (not inserted)
   Value *Args[] = {NewBinOp, Op1};
@@ -1249,6 +1249,8 @@ static Instruction *moveShiftAfterMinMax(IntrinsicInst *II, InstCombiner::Builde
   return NewMax;
 }
 
+
+
 /// Match a sadd_sat or ssub_sat which is using min/max to clamp the value.
 Instruction *InstCombinerImpl::matchSAddSubSat(IntrinsicInst &MinMax1) {
   Type *Ty = MinMax1.getType();