How to Use arm Instruction Set in Apple llvm3.0

In the llvm gcc4.2 compiler, Apple uses the prompt interface in xcode to explicitly provide programmers with options for compiling the target code into arm. In Apple llvm3.0, this option is missing.

Because the apple A4/A5 processor using the armv7a architecture has the thumb-2 instruction set, the thumb Code further improves the computing capability while ensuring the closeness. Therefore, Apple sets the project configuration to compile as thumb code by default.

Since llvm compilation options are basically compatible with GCC, we only need to manually add-marm to the compilation options.

However, the traditional GCC compilation option is-mthumb. By default, it compiles the code into an arm instruction set. Therefore, the-marm compilation option may not be provided. But-marm does work in Apple llvm3.0. Hehaoha