When I joined the iPhone dev team, about a week after the first iPhone came out, I came in as an experienced reverse-engineer on x86/PPC but had never touched A

When I joined the iPhone dev team, about a week after the first iPhone came out, I came in as an experienced reverse-engineer on x86/PPC but had never touched ARM. Within a few weeks (after writing a dead simple decompiler, among other things), it became one of my favorite ISAs. Why? Conditional execution and free shifting. They touch on conditional execution, but they don't really point out how amazing it is. It makes conditional math code, if nothing else, insanely simple and elegant, not to mention fast as hell. As for the free shifts, I'm sort of amazed they aren't touched on in the article -- they make life very easy. In ARM, you can do a shift on the result of most instructions. E.g. you can do add r0, r1, r2, LSL #4, which is equivalent to r0 = (r1 + r2) << 4. If you're commonly dealing with powers of two, this is an absolute godsend.