A lot of hobbyist ones, e.g. But even for mainstream compilers, arm has been a second-class citizen where developers would not necessarily test on arm. E.g. I used to work on V8, and we had partners at ARM who would help support the 32- and 64-bit ports. While I often did go ahead and port my changes to arm, it wasn't always required, as they could do heavy lifting and debugging for us, sometimes. We didn't have arm hardware on our desks to test; V8 literally has its own CPU simulators built into it, just for running the generated code from its own JITs. We had good regression testing infrastructure, but there is nothing quite like having first-class, on-desk hardware to test with, preferrably to develop directly on.