Target configuration with ct-ng and configurability of the resulting toolchain (regarding target)

Target configuration with ct-ng and configurability of the resulting toolchain (regarding target)

[Erik Leunissen]

Hi,

Can someone please enlighten me about how the choices in ct-ng regarding 
target options, affect the targets or architectures that the resulting 
toolchain can generate code for?

Context: I'm in the process of making a toolchain that supports arm 
architectures as generically as possible, while still being able to 
generate code that is tuned for a specific cpu, by make choices that 
deviate from the ct-ng configuration when invoking the compiler (using 
options like -march -m32/64 -mtune, -mcpu, -mfpu). At the very least I'd 
like to generate code specifically tuned/optimised for cortex-a53 and 
cortex-a8.


Examples:

Suppose I configure the target as "arm", and specify "cortex-a53" for 
"Emit assembly for CPU" (in the category "toolchain optimisations"). Can 
I still use the resulting toolchain to generate code for cortex-a8 by 
specifying "-march=cortex-a8" on the compiler command line?

Likewise:
Suppose I configure the toolchain for 64-Bitness. Can I still use the 
resulting toolchain to generate code for 32-bit architectures by 
specifying "-m32" on the command line? And how about the converse case?

Again, likewise:
Suppose I configure the toolchain for software floating point 
("softfp"). Can I still use the resulting toolchain to generate code 
using hardware fp by specifying "-mfpu=neon-vfpv3" on the command line?


Thanks in advance for any insights or pointers,
Erik Leunissen.