[InstSimplify] Extract commutative and folds into helper (NFCI)

There are a number of and folds that are repeated for both
operand orders. Move these into a helper that is invoked with
both orders.

This is conceptually NFC, but may not be entirely so, as the order
of folds may change.

Author: nikic

llvm/lib/Analysis/InstructionSimplify.cpp

@@ -1993,6 +1993,48 @@ static Value *simplifyLogicOfAddSub(Value *Op0, Value *Op1,
   return nullptr;
 }
 
+// Commutative patterns for and that will be tried with both operand orders.
+static Value *simplifyAndCommutative(Value *Op0, Value *Op1,
+                                     const SimplifyQuery &Q,
+                                     unsigned MaxRecurse) {
+  // ~A & A =  0
+  if (match(Op0, m_Not(m_Specific(Op1))))
+    return Constant::getNullValue(Op0->getType());
+
+  // (A | ?) & A = A
+  if (match(Op0, m_c_Or(m_Specific(Op1), m_Value())))
+    return Op1;
+
+  // (X | ~Y) & (X | Y) --> X
+  Value *X, *Y;
+  if (match(Op0, m_c_Or(m_Value(X), m_Not(m_Value(Y)))) &&
+      match(Op1, m_c_Or(m_Deferred(X), m_Deferred(Y))))
+    return X;
+
+  // If we have a multiplication overflow check that is being 'and'ed with a
+  // check that one of the multipliers is not zero, we can omit the 'and', and
+  // only keep the overflow check.
+  if (isCheckForZeroAndMulWithOverflow(Op0, Op1, true))
+    return Op1;
+
+  // -A & A = A if A is a power of two or zero.
+  if (match(Op0, m_Neg(m_Specific(Op1))) &&
+      isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT))
+    return Op1;
+
+  // This is a similar pattern used for checking if a value is a power-of-2:
+  // (A - 1) & A --> 0 (if A is a power-of-2 or 0)
+  if (match(Op0, m_Add(m_Specific(Op1), m_AllOnes())) &&
+      isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT))
+    return Constant::getNullValue(Op1->getType());
+
+  if (Value *V =
+          simplifyAndOrWithICmpEq(Instruction::And, Op0, Op1, Q, MaxRecurse))
+    return V;
+
+  return nullptr;
+}
+
 /// Given operands for an And, see if we can fold the result.
 /// If not, this returns null.
 static Value *simplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
@@ -2020,33 +2062,18 @@ static Value *simplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
   if (match(Op1, m_AllOnes()))
     return Op0;
 
-  // A & ~A  =  ~A & A  =  0
-  if (match(Op0, m_Not(m_Specific(Op1))) || match(Op1, m_Not(m_Specific(Op0))))
-    return Constant::getNullValue(Op0->getType());
-
-  // (A | ?) & A = A
-  if (match(Op0, m_c_Or(m_Specific(Op1), m_Value())))
-    return Op1;
-
-  // A & (A | ?) = A
-  if (match(Op1, m_c_Or(m_Specific(Op0), m_Value())))
-    return Op0;
-
-  // (X | Y) & (X | ~Y) --> X (commuted 8 ways)
-  Value *X, *Y;
-  if (match(Op0, m_c_Or(m_Value(X), m_Not(m_Value(Y)))) &&
-      match(Op1, m_c_Or(m_Deferred(X), m_Deferred(Y))))
-    return X;
-  if (match(Op1, m_c_Or(m_Value(X), m_Not(m_Value(Y)))) &&
-      match(Op0, m_c_Or(m_Deferred(X), m_Deferred(Y))))
-    return X;
+  if (Value *Res = simplifyAndCommutative(Op0, Op1, Q, MaxRecurse))
+    return Res;
+  if (Value *Res = simplifyAndCommutative(Op1, Op0, Q, MaxRecurse))
+    return Res;
 
   if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::And))
     return V;
 
   // A mask that only clears known zeros of a shifted value is a no-op.
   const APInt *Mask;
   const APInt *ShAmt;
+  Value *X, *Y;
   if (match(Op1, m_APInt(Mask))) {
     // If all bits in the inverted and shifted mask are clear:
     // and (shl X, ShAmt), Mask --> shl X, ShAmt
@@ -2074,42 +2101,6 @@ static Value *simplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
       return ConstantInt::getNullValue(Op1->getType());
   }
 
-  // If we have a multiplication overflow check that is being 'and'ed with a
-  // check that one of the multipliers is not zero, we can omit the 'and', and
-  // only keep the overflow check.
-  if (isCheckForZeroAndMulWithOverflow(Op0, Op1, true))
-    return Op1;
-  if (isCheckForZeroAndMulWithOverflow(Op1, Op0, true))
-    return Op0;
-
-  // A & (-A) = A if A is a power of two or zero.
-  if (match(Op0, m_Neg(m_Specific(Op1))) ||
-      match(Op1, m_Neg(m_Specific(Op0)))) {
-    if (isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI,
-                               Q.DT))
-      return Op0;
-    if (isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI,
-                               Q.DT))
-      return Op1;
-  }
-
-  // This is a similar pattern used for checking if a value is a power-of-2:
-  // (A - 1) & A --> 0 (if A is a power-of-2 or 0)
-  // A & (A - 1) --> 0 (if A is a power-of-2 or 0)
-  if (match(Op0, m_Add(m_Specific(Op1), m_AllOnes())) &&
-      isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT))
-    return Constant::getNullValue(Op1->getType());
-  if (match(Op1, m_Add(m_Specific(Op0), m_AllOnes())) &&
-      isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT))
-    return Constant::getNullValue(Op0->getType());
-
-  if (Value *V =
-          simplifyAndOrWithICmpEq(Instruction::And, Op0, Op1, Q, MaxRecurse))
-    return V;
-  if (Value *V =
-          simplifyAndOrWithICmpEq(Instruction::And, Op1, Op0, Q, MaxRecurse))
-    return V;
-
   if (Value *V = simplifyAndOrOfCmps(Q, Op0, Op1, true))
     return V;