This is the mail archive of the gcc@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: rtx_cost of insns


On Mon, Jun 29, 2015 at 09:34:40AM -0500, Segher Boessenkool wrote:
> On Mon, Jun 29, 2015 at 05:16:39PM +0930, Alan Modra wrote:
> > Note that we already have insn_rtx_cost, and it returns a minimum cost
> > for a SET, so register move insns get a cost of 1 insn.  However,
> > despite insn_rtx_cost starting life in combine.c, even combine doesn't
> > use it in all whole insn cases.  :-(
> 
> In what cases does it not?

Practically all of the occurrences of set_src_cost in combine.c can be
called on whole insns.  By "whole insn" I mean of course the right
hand side of a set, or a single set inside a parallel.  I'm not saying
that this causes trouble, since I haven't seen a register move there
(but I haven't looked very hard either).

-- 
Alan Modra
Australia Development Lab, IBM


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]