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Re: intermodule optimisation patch
- From: <tm_gccmail at mail dot kloo dot net>
- To: Chris Lattner <sabre at nondot dot org>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Fri, 30 May 2003 21:52:26 -0700 (PDT)
- Subject: Re: intermodule optimisation patch
On Thu, 29 May 2003, Chris Lattner wrote:
> > Both the SGI cc and Digital cc seem to be derived from Fredrick Chow's
> > Master thesis compiler uses UCSD Pascal P-code internally. When configured
> > for IPO, they output the p-code into the output files and let the linker
> > do the rest of the code generation and linking.
>
> Do you know where to get information about the form that pcode actually
> uses (such as what kind of operations it includes, etc). I'm interested
> to see what type of representation is, but haven't run across any concrete
> details about it...
>
> Thanks!
>
> -Chris
It's the stack-based virtual machine used by the UCSD Pascal
implementation from the early 80s. There were versions on multiple
platforms including VAXen, Apple II (Apple Pascal), and Western Digital
even built a hardware implementation of the VM called the pEngine.
It's a basic virtual stack machine. Load from memory, push onto stack. Pop
from stack, store in memory. Add top two items on stack. The usual stuff.
IIRC There's documentation in multiple places including the appendix of
Fredrick Chow's thesis.
Toshi