RP2040MMIO: A hardware access layer for the RP2040

[ole (Ole Begemann)]

@rauhul

I'd suggest using a nightly toolchain to make sure you have these changes, as they dramatically improve compile times for very large macro uses.

Here's a quick comparison building @nikolai.ruhe's code with a nightly toolchain vs. Swift 5.9.2.

Environment:

• M1 Pro Macbook Pro, 10 cores, 32 GB RAM
• macOS 13.6.3
• Timing swift build (debug build) and swift build -c release (release build)
• Ran swift package clean before each build

	Swift 5.9.2	Nightly 2024-01-14	Factor
Debug	379 s (6:19 min)	309 s (5:09 min)	0.82×
Release	499 s (8:19 min)	404 s (6:44 min)	0.81×

Still (too) long, but a very nice speedup!

@rauhul

I was able to bring a ~10 minute compile down to ~10s with all of these changes combined.

Oh boy, that sounds almost too good to be true. Looking forward to these improvements!