Abstract: Techniques to facilitate modifications to program execution in an application at runtime are disclosed herein. In at least one implementation, a copy of a code block associated with code is created. A flag associated with the copy of the code block is modified to mark the copy of the code block as having a native code version of the code. Metadata associated with the copy of the code block is modified to identify alternative code to run instead of the native code version of the code. A pointer associated with the code block is modified to point to a trampoline function. The trampoline function checks whether the code block is associated with a modification, and when the code block is associated with the modification, then the trampoline function calls the copy of the code block to invoke the alternative code by virtue of the flag and the metadata.

Abstract: Techniques to facilitate previewing changes to visual elements of a mobile application at different display sizes are disclosed herein. In at least one implementation, screenshot capture instructions provided by an application development and optimization platform are received that indicate at least one requested display size at which to provide a view of the mobile application. An actual screenshot of the view of the mobile application is captured, and a virtual screenshot of the view is rendered by resizing the actual screenshot to the requested display size indicated in the screenshot capture instructions. The actual screenshot of the view and the virtual screenshot of the view rendered at the requested display size are transferred for delivery to the application development and optimization platform.

Abstract: Techniques to facilitate prevention of just-in-time (JIT) translations of application functions are disclosed herein. In at least one implementation, a JIT translation function of an operating system is modified in memory to redirect the JIT translation function to execute alternative code when the JIT translation function is called. When the JIT translation function is called for an application function, the alternative code is executed to determine whether the application function has been modified. When the alternative code determines that the application function has been modified, the JIT translation function is prevented from translating the application function into a native machine code version. When the alternative code determines that the application function has not been modified, the JIT translation function is allowed to translate the application function into the native machine code version.

Abstract: Techniques to bypass system context checks to facilitate opening shared-object libraries are disclosed herein. In at least one implementation, a copy of a header of a shared-object library loaded by a runtime system is created. The header of the shared-object library loaded by the runtime system is patched with code configured to call an open function, wherein the code patched into the header of the shared-object library executes and calls the open function from the shared-object library loaded by the runtime system, the call to the open function is recognized as within a context of the runtime system, and the shared-object library is allowed to be opened. A pointer to the shared-object library opened in memory is received, and the header of the shared-object library is restored to an original version using the copy of the header of the shared-object library.

Abstract: Techniques to facilitate prevention of just-in-time (JIT) translations of application functions are disclosed herein. In at least one implementation, a JIT translation function of an operating system is modified in memory to redirect the JIT translation function to execute alternative code when the JIT translation function is called. When the JIT translation function is called for an application function, the alternative code is executed to determine whether the application function has been modified. When the alternative code determines that the application function has been modified, the JIT translation function is prevented from translating the application function into a native machine code version. When the alternative code determines that the application function has not been modified, the JIT translation function is allowed to translate the application function into the native machine code version.

Abstract: Techniques to bypass system context checks to facilitate opening shared-object libraries are disclosed herein. In at least one implementation, a copy of a header of a shared-object library loaded by a runtime system is created. The header of the shared-object library loaded by the runtime system is patched with code configured to call an open function, wherein the code patched into the header of the shared-object library executes and calls the open function from the shared-object library loaded by the runtime system, the call to the open function is recognized as within a context of the runtime system, and the shared-object library is allowed to be opened. A pointer to the shared-object library opened in memory is received, and the header of the shared-object library is restored to an original version using the copy of the header of the shared-object library.

Abstract: Techniques to facilitate previewing changes to visual elements of a mobile application at different display sizes are disclosed herein. In at least one implementation, screenshot capture instructions provided by an application development and optimization platform are received that indicate at least one requested display size at which to provide a view of the mobile application. An actual screenshot of the view of the mobile application is captured, and a virtual screenshot of the view is rendered by resizing the actual screenshot to the requested display size indicated in the screenshot capture instructions. The actual screenshot of the view and the virtual screenshot of the view rendered at the requested display size are transferred for delivery to the application development and optimization platform.