This option enforces ARM-only code. The compiler behaves as if Thumb is absent from the target architecture.
The compiler propagates the --arm_only option to the assembler and the linker.
Default
For targets that support the ARM instruction set, the default is --arm. For targets that do not support the ARM instruction set, the default is --thumb.
Example
armcc --arm_only myprog.c
Note
If you specify armcc --arm_only --thumb myprog.c, this does not mean that the compiler checks your code to ensure that no Thumb code is present. It means that --thumb overrides --arm_only, because of command-line ordering.