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Re: RFC -- update_equiv_regs and friends
- To: John Wehle <john at feith dot com>
- Subject: Re: RFC -- update_equiv_regs and friends
- From: Jeffrey A Law <law at redhat dot com>
- Date: Fri, 02 Mar 2001 01:29:12 -0700
- cc: amylaar at cambridge dot redhat dot com, gcc at gcc dot gnu dot org, rth at redhat dot com
- Reply-To: law at redhat dot com
In message <200103020244.VAA00565@jwlab.FEITH.COM>you write:
> > > 2) Change update_equiv_regs so it doesn't promote a REG_EQUAL note
> > > to a REG_EQUIV if there's a register mentioned.
> >
> > Promoting REG_EQUAL to REG_EQUIV is an important optimization for some
> > procesors for sums involving the stack pointer, the frame pointer,
> > virtual_stack_var_rtx and the argument pointer.
>
> So allow the promation if the register is FIXED_REGISTERS?
If it's fixed, or otherwise globally live and unchanging. So for example
we can include the frame pointer, even if it isn't fixed. It's a little
more difficult to determine if we can use the arg pointer :-)
jeff