1. A computer-implemented method for executing a native code module, comprising: loading the native code module into a secure runtime environment of a computing system, including loading the native code module in a valid memory region for the native code module; and constraining store instructions in the native code module, including bounding the valid memory region for the native code module with one or more guard regions, wherein the one or more guard regions are large enough to prevent a store address of at least one multi-register addressing mode of the store instructions from being outside of the one or more guard regions.