This seemed a bit harsh, but (after consulting Wikipedia) I'm guessing you're trying to say that even after doubling to 16, it still sucks compared with "common RISC processors (which typically have 32–64 registers) or VLIW-like machines such as the IA-64 (which has 128 registers)."
Sorry. I didn't want to sound harsh. The x86 ISA has a register starvation problem. I am sure the phone I am writing this on has a far more elegant and modern processor than the PC I'll return to after I finish lunch.
The sooner we can ditch x86 (and that includes amd64), the better.
The problem with IA64 being that Intel designed/patented it so that they could bring in royalties if/when everyone went to 64-bit and used their architecture. I'm thanking amd64 for saving us from creating a new generation of processors where everyone was paying an Intel tax. It may have a superior design, but I don't want every processor in a desktop/laptop out there to be a revenue generation machine for a single company, even when the processor's manufacturer is different.
I was using 64-bit processors and OSs a couple years before Intel shipped IA64. Try to google SPARC and MIPS.
What AMD did was to extend the x86 ISA with a handful extra registers and double the size of all of them. This allowed x86 to survive until these days, slowed down the migration towards 64-bit computing and confined much better architectures to specific niches.
