That is really important to note: the spread of the Cortex-M0 has been amazing for embedded software. Before, compilers were vendor-managed for their proprietary core, and now they are basically mainline GCC because of the uniform use of the ARM instruction set.

I remember using a vendor fork of GCC 2 (released in 1999) to compile for a specific microcontroller in 2015, but since that vendor now releases Cortex-M0's, the vendor-blessed compiler uses a near-mainline GCC.