Hacker News new | ask | show | jobs
by pyre 6083 days ago
IIRC 64-bit isn't just about memory size. x86_64 is a chance to use things like SSE for floating point rather than x87. The older floating point units are still on the processors, but in a depreciated fashion (Windows/Linux ABI don't use them). You can use SSE for floating point on a 32-bit system if you compile all of your apps yourself (ala Gentoo), but then the resulting binaries are not 'x86-compatible' because every x86 processor is not guaranteed to have SSE support.

As you can see, x86-64 isn't just about memory size.
1 comments
_cbsz 6083 days ago
You also get a ton more registers, 64-bit registers, and other nice processor features.
link
rbanffy 6082 days ago
A ton as in "8", right?

It's not a ton by any measure...

link
ZeroGravitas 6082 days ago
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)."
link
rbanffy 6082 days ago
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.

link
pyre 6082 days ago
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.
link
rbanffy 6082 days ago
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.

No, I will not thank AMD for that.

link