+/// getBinOpIdentity - Return the identity for the given binary operation,
+/// i.e. a constant C such that X op C = X and C op X = X for every X. It
+/// returns null if the operator doesn't have an identity.
+Constant *ConstantExpr::getBinOpIdentity(unsigned Opcode, Type *Ty) {
+ switch (Opcode) {
+ default:
+ // Doesn't have an identity.
+ return 0;
+
+ case Instruction::Add:
+ case Instruction::Or:
+ case Instruction::Xor:
+ return Constant::getNullValue(Ty);
+
+ case Instruction::Mul:
+ return ConstantInt::get(Ty, 1);
+
+ case Instruction::And:
+ return Constant::getAllOnesValue(Ty);
+ }
+}
+
+/// getBinOpAbsorber - Return the absorbing element for the given binary
+/// operation, i.e. a constant C such that X op C = C and C op X = C for
+/// every X. For example, this returns zero for integer multiplication.
+/// It returns null if the operator doesn't have an absorbing element.
+Constant *ConstantExpr::getBinOpAbsorber(unsigned Opcode, Type *Ty) {
+ switch (Opcode) {
+ default:
+ // Doesn't have an absorber.
+ return 0;
+
+ case Instruction::Or:
+ return Constant::getAllOnesValue(Ty);
+
+ case Instruction::And:
+ case Instruction::Mul:
+ return Constant::getNullValue(Ty);
+ }
+}
+