1. A computer system for compiling a source code into an object code, the computer system comprising: a memory storing instructions; and a processor configured to execute the instructions to implement: a first converter configured to convert the source code into an intermediate code; a first generator configured to generate a modified-intermediate code by replacing a first command among commands included in the intermediate code, with a conditional branch command, in response to the intermediate code satisfying: a first condition in which a first result of the first command is handled as a constant; a second condition in which the first result of the first command and a second result of a second command among the commands are concurrently used in a third command among the commands; a third condition in which a third result of the third command is determined by the constant regardless of the second result of the second command; and a fourth condition in which the second result of the second command and an intermediate result of the second command are not used in the commands other than the third command in the intermediate code; and a second converter configured to convert the modified-intermediate code into the object code, wherein the first command does not exist in the modified-intermediate code after the first command is replaced with the conditional branch command.