[PatternMatch] Add m_BinOp/m_c_BinOp with specific opcode

[rampitec]

Inherit from BinaryOp_match instead of duplication of match.

[rampitec]

Make tidy happy.

[spatel]

LGTM - there may be more potential uses in functions like InstCombinerImpl::SimplifyUsingDistributiveLaws() or other reassociation folds.

[rampitec]

In D113508#3132309, @spatel wrote:

LGTM - there may be more potential uses in functions like InstCombinerImpl::SimplifyUsingDistributiveLaws() or other reassociation folds.

D114038 adds 2 more places. That's all I found.

I can also add the same matcher to the m_UnOp for completeness, but I didn't find a use for it (and that also means there is no code which would test template instantiation).

llvm/include/llvm/IR/PatternMatch.h

 inline OverflowingBinaryOp_match<LHS, RHS, Instruction::Shl,
                                  OverflowingBinaryOperator::NoUnsignedWrap>
 m_NUWShl(const LHS &L, const RHS &R) {
   return OverflowingBinaryOp_match<LHS, RHS, Instruction::Shl,
                                    OverflowingBinaryOperator::NoUnsignedWrap>(
       L, R);
 }
 
+template <typename LHS_t, typename RHS_t, bool Commutable = false>
+struct SpecificBinaryOp_match {
+  unsigned Opcode;
+  LHS_t L;
+  RHS_t R;
+
+  // The evaluation order is always stable, regardless of Commutability.
+  // The LHS is always matched first.
+  SpecificBinaryOp_match(unsigned Opcode, const LHS_t &LHS, const RHS_t &RHS)
+      : Opcode(Opcode), L(LHS), R(RHS) {}
+
+  template <typename OpTy> bool match(OpTy *V) {
+    if (V->getValueID() == Value::InstructionVal + Opcode) {
+      auto *I = cast<BinaryOperator>(V);
+      return (L.match(I->getOperand(0)) && R.match(I->getOperand(1))) ||
+             (Commutable && L.match(I->getOperand(1)) &&
+              R.match(I->getOperand(0)));
+    }
+    if (auto *CE = dyn_cast<ConstantExpr>(V))
+      return CE->getOpcode() == Opcode &&
+             ((L.match(CE->getOperand(0)) && R.match(CE->getOperand(1))) ||
+              (Commutable && L.match(CE->getOperand(1)) &&
+               R.match(CE->getOperand(0))));
+    return false;
+  }
+};
+
+/// Matches a specific opcode.
+template <typename LHS, typename RHS>
+inline SpecificBinaryOp_match<LHS, RHS> m_BinOp(unsigned Opcode, const LHS &L,
+                                                const RHS &R) {
+  return SpecificBinaryOp_match<LHS, RHS>(Opcode, L, R);
+}
+
 //===----------------------------------------------------------------------===//
 // Class that matches a group of binary opcodes.
 //
 template <typename LHS_t, typename RHS_t, typename Predicate>
 struct BinOpPred_match : Predicate {
   LHS_t L;
   RHS_t R;
 

 /// Swaps the predicate if operands are commuted.
 template <typename LHS, typename RHS>
 inline CmpClass_match<LHS, RHS, ICmpInst, ICmpInst::Predicate, true>
 m_c_ICmp(ICmpInst::Predicate &Pred, const LHS &L, const RHS &R) {
   return CmpClass_match<LHS, RHS, ICmpInst, ICmpInst::Predicate, true>(Pred, L,
                                                                        R);
 }
 
+/// Matches a specific opcode with LHS and RHS in either order.
+template <typename LHS, typename RHS>
+inline SpecificBinaryOp_match<LHS, RHS, true>
+m_c_BinOp(unsigned Opcode, const LHS &L, const RHS &R) {
+  return SpecificBinaryOp_match<LHS, RHS, true>(Opcode, L, R);
+}
+
 /// Matches a Add with LHS and RHS in either order.
 template <typename LHS, typename RHS>
 inline BinaryOp_match<LHS, RHS, Instruction::Add, true> m_c_Add(const LHS &L,
                                                                 const RHS &R) {
   return BinaryOp_match<LHS, RHS, Instruction::Add, true>(L, R);
 }
 
 /// Matches a Mul with LHS and RHS in either order.

llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

static Instruction *reassociateFCmps(BinaryOperator &BO,
   // There are 4 commuted variants of the pattern. Canonicalize operands of this
   // logic op so an fcmp is operand 0 and a matching logic op is operand 1.
   Value *Op0 = BO.getOperand(0), *Op1 = BO.getOperand(1), *X;
   FCmpInst::Predicate Pred;
   if (match(Op1, m_FCmp(Pred, m_Value(), m_AnyZeroFP())))
     std::swap(Op0, Op1);
 
   // Match inner binop and the predicate for combining 2 NAN checks into 1.
-  BinaryOperator *BO1;
+  Value *BO10, *BO11;
   FCmpInst::Predicate NanPred = Opcode == Instruction::And ? FCmpInst::FCMP_ORD
                                                            : FCmpInst::FCMP_UNO;
   if (!match(Op0, m_FCmp(Pred, m_Value(X), m_AnyZeroFP())) || Pred != NanPred ||
-      !match(Op1, m_BinOp(BO1)) || BO1->getOpcode() != Opcode)
+      !match(Op1, m_BinOp(Opcode, m_Value(BO10), m_Value(BO11))))
     return nullptr;
 
   // The inner logic op must have a matching fcmp operand.
-  Value *BO10 = BO1->getOperand(0), *BO11 = BO1->getOperand(1), *Y;
+  Value *Y;
   if (!match(BO10, m_FCmp(Pred, m_Value(Y), m_AnyZeroFP())) ||
       Pred != NanPred || X->getType() != Y->getType())
     std::swap(BO10, BO11);
 
   if (!match(BO10, m_FCmp(Pred, m_Value(Y), m_AnyZeroFP())) ||
       Pred != NanPred || X->getType() != Y->getType())
     return nullptr;
 
if (match(Op0, m_OneUse(m_Not(m_Value(A)))) &&
     return BinaryOperator::CreateNot(AndOr);
   }
 
   // The 'not' ops may require reassociation.
   // (A & ~B) & ~C --> A & ~(B | C)
   // (~B & A) & ~C --> A & ~(B | C)
   // (A | ~B) | ~C --> A | ~(B & C)
   // (~B | A) | ~C --> A | ~(B & C)
-  BinaryOperator *BO;
-  if (match(Op0, m_OneUse(m_BinOp(BO))) && BO->getOpcode() == Opcode) {
-    Value *C;
-    if (match(BO, m_c_BinOp(m_Value(A), m_Not(m_Value(B)))) &&
-        match(Op1, m_Not(m_Value(C)))) {
-      Value *FlippedBO = Builder.CreateBinOp(FlippedOpcode, B, C);
-      return BinaryOperator::Create(Opcode, A, Builder.CreateNot(FlippedBO));
-    }
-  }
+  if (match(Op0, m_OneUse(m_c_BinOp(Opcode, m_Value(A), m_Not(m_Value(B))))) &&
 
   return nullptr;
 }
 
 bool InstCombinerImpl::shouldOptimizeCast(CastInst *CI) {
   Value *CastSrc = CI->getOperand(0);
 
   // Noop casts and casts of constants should be eliminated trivially.