1. A system, comprising: one or more computing devices; wherein the one or more computing devices are configured to: obtain an indication of one or more user-mode software programs to be deployed at a constrained computing environment, wherein a deployment policy of the constrained computing environment indicates the particular user-mode software programs whose execution is permitted at the constrained computing environment; determine, based at least in part on a statement-level analysis of source code of at least one user-mode software program of the one or more user-mode software programs, (a) a retention set of operating system source code sections, and (b) an expendable set of operating system source code sections, wherein the retention set corresponds to operations to be performed on behalf of the one or more user-mode software programs in the constrained computing environment, wherein the expendable set corresponds to operations which are not expected to be performed on behalf of the one or more user-mode software programs, wherein the retention set comprises a particular statement of a particular function, and wherein the expendable set comprises a different statement of the particular function; generate, using a source code repository of an operating system, a space-optimized binary version of at least a portion of an operating system to be deployed for use by the one or more user-mode software programs at the constrained computing environment, wherein the space-optimized binary version (a) includes executable code corresponding to the retention set and (b) does not include at least some executable code corresponding to the expendable set; and cause a deployment of at least the space-optimized binary version to the constrained computing environment.