[patch] Merge cfo-branch, RTL sequence abstraction (part 1)

[Daniel Jacobowitz]

On Sat, Jan 07, 2006 at 11:12:25AM -0700, Roger Sayle wrote:
> This allows target backends to provide size information for their
> functionality.  On CISC architectures such as x86, vax, etc...
> this is the usual way that this size information is provided to
> the middle-end.  In recent years, the "length" insn attribute has
> been available for recognized instructions, but rtx_costs is used
> early during the compiler to estimate sizes prior to instruction
> selection or even RTL expansion.  i.e. rtx_cost(op) should the
> speed/size of operation op, even if it isn't representable in a
> single instruction.

Of course I'm aware of this (and most of the rest of your message);
that wasn't my point.  By the time we're doing CFO oughtn't we to have
established insns and their lengths?  We're after reload, we've
selected variants of everything by now.

Again: CFO is a size optimization.

> Gabor's current approach of assuming constant length for each INSN_P

I didn't suggest that.  I suggested using get_attr_length.

-- 
Daniel Jacobowitz
CodeSourcery