Using ARMv6 instructions

By default, qcc provides only ARMv4 instructions. This ensures that all compiled code will run on any supported ARM processor.

The ARMv6 processor introduces a number of new instructions that may provide performance benefits for certain code. For example, DSP algorithms can take advantage of the new media instructions.

This requires the correct gcc and binutils versions that implement ARMv6 migration:

gcc 4.2
binutils 2.18

There are a number of ways you can optimize ARMv6 operations:

implement the ARMv6-specific operations in assembler files
modify the compiler flags so that the compiler can use ARMv6 instructions where appropriate.
If you're using the QNX recursive Makefile structure:
- Compile globally for ARMv6, and add the following to the lowest level Makefile:
```
   CCFLAGS += -march=armv6
       
```
- Compile specific object files only for ARMv6, and add the following to the file common.mk:
```
   CCFLAGS_<name>_arm = -march=armv6
   CCFLAGS += $(CCFLAGS_$(basename $@)_$(CPU))
```

CAUTION:

The object files, libraries, and binaries that are compiled to use ARMv6 instructions can only run on a target with an ARMv6 CPU. On a non-ARMv6 CPU, this causes an undefined instruction exception (SIGILL signal) or may result in unpredictable behavior.