[PatternMatch] Use m_Not instead of m_c_Xor with m_AllOnes() (#96837)

Author: AZero13

llvm/include/llvm/IR/PatternMatch.h

@@ -2309,6 +2309,22 @@ m_UnordFMin(const LHS &L, const RHS &R) {
   return MaxMin_match<FCmpInst, LHS, RHS, ufmin_pred_ty>(L, R);
 }
 
+/// Matches a 'Not' as 'xor V, -1' or 'xor -1, V'.
+/// NOTE: we first match the 'Not' (by matching '-1'),
+/// and only then match the inner matcher!
+template <typename ValTy>
+inline BinaryOp_match<cst_pred_ty<is_all_ones>, ValTy, Instruction::Xor, true>
+m_Not(const ValTy &V) {
+  return m_c_Xor(m_AllOnes(), V);
+}
+
+template <typename ValTy>
+inline BinaryOp_match<cst_pred_ty<is_all_ones, false>, ValTy, Instruction::Xor,
+                      true>
+m_NotForbidPoison(const ValTy &V) {
+  return m_c_Xor(m_AllOnesForbidPoison(), V);
+}
+
 //===----------------------------------------------------------------------===//
 // Matchers for overflow check patterns: e.g. (a + b) u< a, (a ^ -1) <u b
 // Note that S might be matched to other instructions than AddInst.
@@ -2343,13 +2359,13 @@ struct UAddWithOverflow_match {
         return L.match(AddLHS) && R.match(AddRHS) && S.match(ICmpRHS);
 
     Value *Op1;
-    auto XorExpr = m_OneUse(m_Xor(m_Value(Op1), m_AllOnes()));
-    // (a ^ -1) <u b
+    auto XorExpr = m_OneUse(m_Not(m_Value(Op1)));
+    // (~a) <u b
     if (Pred == ICmpInst::ICMP_ULT) {
       if (XorExpr.match(ICmpLHS))
         return L.match(Op1) && R.match(ICmpRHS) && S.match(ICmpLHS);
     }
-    //  b > u (a ^ -1)
+    //  b > u (~a)
     if (Pred == ICmpInst::ICMP_UGT) {
       if (XorExpr.match(ICmpRHS))
         return L.match(Op1) && R.match(ICmpLHS) && S.match(ICmpRHS);
@@ -2659,22 +2675,6 @@ m_NSWNeg(const ValTy &V) {
   return m_NSWSub(m_ZeroInt(), V);
 }
 
-/// Matches a 'Not' as 'xor V, -1' or 'xor -1, V'.
-/// NOTE: we first match the 'Not' (by matching '-1'),
-/// and only then match the inner matcher!
-template <typename ValTy>
-inline BinaryOp_match<cst_pred_ty<is_all_ones>, ValTy, Instruction::Xor, true>
-m_Not(const ValTy &V) {
-  return m_c_Xor(m_AllOnes(), V);
-}
-
-template <typename ValTy>
-inline BinaryOp_match<cst_pred_ty<is_all_ones, false>, ValTy, Instruction::Xor,
-                      true>
-m_NotForbidPoison(const ValTy &V) {
-  return m_c_Xor(m_AllOnesForbidPoison(), V);
-}
-
 /// Matches an SMin with LHS and RHS in either order.
 template <typename LHS, typename RHS>
 inline MaxMin_match<ICmpInst, LHS, RHS, smin_pred_ty, true>

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -30557,7 +30557,7 @@ static std::pair<Value *, BitTestKind> FindSingleBitChange(Value *V) {
     bool Not = false;
     // Check if we have a NOT
     Value *PeekI;
-    if (match(I, m_c_Xor(m_Value(PeekI), m_AllOnes())) ||
+    if (match(I, m_Not(m_Value(PeekI))) ||
         match(I, m_Sub(m_AllOnes(), m_Value(PeekI)))) {
       Not = true;
       I = dyn_cast<Instruction>(PeekI);

llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp

@@ -216,7 +216,7 @@ dropRedundantMaskingOfLeftShiftInput(BinaryOperator *OuterShift,
   // ((1 << MaskShAmt) - 1)
   auto MaskA = m_Add(m_Shl(m_One(), m_Value(MaskShAmt)), m_AllOnes());
   // (~(-1 << maskNbits))
-  auto MaskB = m_Xor(m_Shl(m_AllOnes(), m_Value(MaskShAmt)), m_AllOnes());
+  auto MaskB = m_Not(m_Shl(m_AllOnes(), m_Value(MaskShAmt)));
   // (-1 l>> MaskShAmt)
   auto MaskC = m_LShr(m_AllOnes(), m_Value(MaskShAmt));
   // ((-1 << MaskShAmt) l>> MaskShAmt)