OT: x86 machine code [Was: Re: Self modifying code, lambda calculus - Re: ENIAC programming]

Toby Thain toby at telegraphics.com.au
Fri Sep 18 08:06:32 CDT 2015

On 2015-09-18 7:06 AM, Pontus Pihlgren wrote:
> On Fri, Sep 18, 2015 at 06:58:24AM -0400, Mouse wrote:
>>> You have a lot of byte code virtual machines out there.
>> Such as every x86 processor since, what, the Pentium?  They're all RISC
>> cores (designed for and) running an x86 emulator.
> I've been told this more than a few times and read it in various places.
> It always make me wonder, could we not allow a mode in modern Intel
> processors that lets us bypass the x86 code emulation/translation and
> run "directly on the metal" (if there were such a thing).
> The purpose, of course, would be to gain performance. Certainly this
> would already have been done if there was any significant gain to be
> had?

Imho, there are some pretty big negatives to going this route that would 
have to be weighed against possible performance difference:

Intel would be extremely reluctant to expose trade secrets, or have 
customers tightly coupled to implementation details. It would impact 
everything from product development process to roadmap simply to have a 
customer using a non-x86 programmer model. The decoupling implied by an 
instruction set/architecture has always been of great advantage to 
chipmakers, as much as it is to end users.

Don't neglect the massive cost in supporting a new ISA or partial 
compilers, in tools, design, testing, porting, etc.

I think you answered your own question - the cost/benefit rules it out :)


> /P

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