On 25/06/15 17:27, Jeff Law wrote:
> On 06/25/2015 06:28 AM, Richard Earnshaw wrote:
>> On 24/06/15 17:47, Jeff Law wrote:
>>> On 06/24/2015 03:18 AM, Alan Modra wrote:
So in these examples we'd really like register moves to cost one
insn. Hmm, at least, moves from hard regs ought t
On 06/25/2015 06:28 AM, Richard Earnshaw wrote:
On 24/06/15 17:47, Jeff Law wrote:
On 06/24/2015 03:18 AM, Alan Modra wrote:
So in these examples we'd really like register moves to cost one
insn. Hmm, at least, moves from hard regs ought to cost something.
The more I think about it, the more
On 24/06/15 17:47, Jeff Law wrote:
> On 06/24/2015 03:18 AM, Alan Modra wrote:
>>
>> So in these examples we'd really like register moves to cost one
>> insn. Hmm, at least, moves from hard regs ought to cost something.
> The more I think about it, the more I think that's a reasonable step.
> Noth
On 06/24/2015 03:18 AM, Alan Modra wrote:
So in these examples we'd really like register moves to cost one
insn. Hmm, at least, moves from hard regs ought to cost something.
The more I think about it, the more I think that's a reasonable step.
Nothing should have cost 0.
Jeff
-Original Message-
From: gcc-ow...@gcc.gnu.org [mailto:gcc-ow...@gcc.gnu.org] On Behalf Of Richard
Kenner
Sent: Wednesday, June 24, 2015 9:28 PM
To: l...@redhat.com
Cc: gcc@gcc.gnu.org
Subject: Re: set_src_cost lying comment
> These are good examples of things the costing model sim
> These are good examples of things the costing model
> simply wasn't ever designed to consider -- because they weren't
> significant issues on the m68k, vax and other ports in the gcc-1 era.
>
> So I don't really know how to tell you to proceed -- I've considered the
> costing models fundamen
-Original Message-
From: gcc-ow...@gcc.gnu.org [mailto:gcc-ow...@gcc.gnu.org] On Behalf Of Jeff Law
Sent: Wednesday, June 24, 2015 10:36 AM
To: gcc@gcc.gnu.org
Subject: Re: set_src_cost lying comment
On 06/21/2015 11:57 PM, Alan Modra wrote:
> set_src_cost says it is supposed
On 06/24/2015 03:18 AM, Alan Modra wrote:
On Tue, Jun 23, 2015 at 11:05:45PM -0600, Jeff Law wrote:
I certainly agree that the cost of a move, logicals and arithmetic is
essentially the same at the chip level for many processors. But a copy has
other properties that make it "cheaper" -- namely
On Tue, Jun 23, 2015 at 11:05:45PM -0600, Jeff Law wrote:
> I certainly agree that the cost of a move, logicals and arithmetic is
> essentially the same at the chip level for many processors. But a copy has
> other properties that make it "cheaper" -- namely we can often propagate it
> away or arr
On 06/21/2015 11:57 PM, Alan Modra wrote:
set_src_cost says it is supposed to
/* Return the cost of moving X into a register, relative to the cost
of a register move. SPEED_P is true if optimizing for speed rather
than size. */
Now, set_src_cost of a register move (set (reg1) (reg2)),
set_src_cost says it is supposed to
/* Return the cost of moving X into a register, relative to the cost
of a register move. SPEED_P is true if optimizing for speed rather
than size. */
Now, set_src_cost of a register move (set (reg1) (reg2)), is zero.
Why? Well, set_src_cost is used just
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