What compiler is used for the new Nano 33 boards (IoT, BLE, BLE Sense)?

I've got a two part question.

  1. How do I find out what compiler is being used by the Arduino IDE to compile sketches for a given board? I know the Atmel AVR based boards use AVR-GCC, but what about the ARM based boards? How can I verify this information?

Reason I'm asking is...

  1. I'm working on a library for implementing optimal control algorithms and I would like to know what standard math.h functions from GCC 8.1.0 will port over to the Nano 33 BLE via the target compiler. Is there any documentation for the compiler that is used for these boards?

Thanks!

I don't know the answer but the following should reveal it.

Install the board packages if not already done so.
2)
Enable verbose output during compilation in file->preferences
3)
Compile a sketch and analyse the output; it should show the compiler.

Thank you!

So it turns out the GNU ARM embedded toolchain is used; in particular the 7-2017-q4-major release. Verbose output also gives you all the relevant directories you'll need.