Help with define_insn and constraints

[Ian Lance Taylor]

"Dave Korn" <dave.korn@artimi.com> writes:

> > -----Original Message-----
> > From: gcc-owner On Behalf Of Robert Baruch
> > Sent: 23 December 2004 21:21
> 
> > Well, after stepping through reload() a bunch of times, I determined
> > that first, the original instruction looks like this:
> > 
> > [ P56 + 1 ] <- [ R20 + 17 ]
> > 
> > where P56 is a pseudoreg, and R20 is my frame pointer.
> 
>  ?? In your first post, you said you had 19 hard regs.  Does this not imply
> you're trying to keep your frame pointer in a pseudo ??

In gcc, it's normal for the frame pointer to be a pseudo which is
eliminated to the stack pointer, or, in the case of a function which
calls alloca, to be eliminated to some hard register which serves as
the so-called hard frame pointer.  See FRAME_POINTER_REGNUM and
HARD_FRAME_POINTER_REGNUM.

Ian