Frame pointers on armv8-m

Using gcc eabi 8.2.1 for armv8-m (Cortex M33). Compiling with -fno-omit-frame-pointer does not seem to store the frame pointer in any register. Is this not supported for the armv8-m architecture? I don't see an explicit FP defined for that architecture, but could a register still be reserved and used as FP?

  • It depends on what instruction set the compiler is set to. For thumb instruction codes, it is R7. For ARM instruction codes it is R11. I am working with an Atmel Cortex M7 that is compiling into thumb instructions. Do a disassembly and see what register interacts with the SP register at the beginning of the function.