From: Tom de Vries <vries@codesourcery.com>
To: Zdenek Dvorak <rakdver@kam.mff.cuni.cz>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH, PR45098, 3/10]
Date: Wed, 18 May 2011 13:00:00 -0000 [thread overview]
Message-ID: <4DD39392.7000400@codesourcery.com> (raw)
In-Reply-To: <20110518072620.GA18720@kam.mff.cuni.cz>
Hi Zdenek,
thanks for the review.
On 05/18/2011 09:26 AM, Zdenek Dvorak wrote:
>> 2011-05-05 Tom de Vries <tom@codesourcery.com>
>>
>> PR target/45098
>> * tree-ssa-loop-ivopts.c (computation_cost): Prevent cost of 0.
>
> this looks strange. Something like
>
> cost = seq_cost (seq, speed);
> if (MEM_P (rslt))
> the current code;
> else
> cost += rtx_cost (rslt, SET, speed));
>
> would make more sense to me (if I understand correctly what you are
> trying to achieve).
>
Sorry for not putting an explanation in the first place.
I'm trying to achieve that the cost of forcing an int into a reg is not
0. Currently, if the expansion results in an rtx expression rather than
an insn, seq is NULL and seq_cost returns 0, after which
computation_cost returns 0:
...
(gdb) call debug_generic_expr (expr)
2000
(gdb) call debug_rtx (rslt)
(const_int 2000 [0x7d0])
(gdb) p seq
$5 = (rtx) 0x0
...
Using an assert on an x86_64 build, I found this case where seq != NULL_RTX:
...
gdb) call debug_generic_expr (expr)
(int) ((unsigned int) ivtmp.11 * 8)
(gdb) call debug_rtx (rslt)
(reg:SI 62)
(gdb) call debug_rtx (seq)
(insn 4 0 0 (parallel [
(set (reg:SI 62)
(ashift:SI (subreg:SI (reg:DI 59 [ ivtmp.11 ]) 0)
(const_int 3 [0x3])))
(clobber (reg:CC 17 flags))
]) -1
(nil))
...
we don't need to additionally count a regcopy of r62 on top of seq_cost
in this case.
How about:
...
@@ -2866,6 +2878,8 @@ computation_cost (tree expr, bool speed)
if (MEM_P (rslt))
cost += address_cost (XEXP (rslt, 0), TYPE_MODE (type),
TYPE_ADDR_SPACE (type), speed);
+ else if (!REG_P (rslt))
+ cost += (unsigned)rtx_cost (rslt, SET, speed);
return cost;
}
...
?
Thanks
- Tom
next prev parent reply other threads:[~2011-05-18 9:39 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-17 7:23 [PATCH, PR45098] Tom de Vries
2011-05-17 7:25 ` [PATCH, PR45098, 1/10] Tom de Vries
2011-05-19 11:17 ` [PATCH PR45098, 1/10] Proc object-size fix Tom de Vries
2011-05-17 8:12 ` [PATCH, PR45098, 2/10] Tom de Vries
2011-05-18 9:39 ` Zdenek Dvorak
2011-05-17 8:30 ` [PATCH, PR45098, 3/10] Tom de Vries
2011-05-18 10:10 ` Zdenek Dvorak
2011-05-18 13:00 ` Tom de Vries [this message]
[not found] ` <20110518152457.GA13360@kam.mff.cuni.cz>
2011-05-18 19:30 ` Tom de Vries
2011-05-17 8:32 ` [PATCH, PR45098, 4/10] Tom de Vries
2011-05-18 17:46 ` [PATCH PR45098, 4/10] Iv init cost Tom de Vries
2011-05-18 22:59 ` Zdenek Dvorak
2011-05-25 14:20 ` Richard Sandiford
2011-05-26 12:24 ` Tom de Vries
2011-05-31 15:22 ` Richard Sandiford
2011-05-17 8:37 ` [PATCH, PR45098, 5/10] Tom de Vries
2011-05-18 17:48 ` [PATCH PR45098, 5/10] Bound cost Tom de Vries
2011-05-19 4:45 ` Zdenek Dvorak
2011-05-17 8:42 ` [PATCH, PR45098, 6/10] Tom de Vries
2011-05-18 17:48 ` [PATCH PR45098, 6/10] Bound cost - test cases Tom de Vries
2011-05-17 8:58 ` [PATCH, PR45098, 7/10] Tom de Vries
2011-05-18 17:52 ` [PATCH PR45098, 7/10] Nowrap limits iterations Tom de Vries
2011-05-19 4:45 ` Zdenek Dvorak
2011-05-20 12:22 ` Tom de Vries
2011-05-21 18:54 ` Zdenek Dvorak
2011-05-21 22:53 ` Tom de Vries
2011-05-28 17:58 ` Tom de Vries
2011-05-30 15:12 ` Zdenek Dvorak
2011-05-31 9:07 ` Tom de Vries
2011-05-31 9:11 ` Zdenek Dvorak
2011-06-11 10:13 ` Tom de Vries
2011-06-12 1:17 ` Zdenek Dvorak
2011-05-23 14:50 ` H.J. Lu
2011-05-17 9:03 ` [PATCH, PR45098, 8/10] Tom de Vries
2011-05-18 18:23 ` [PATCH PR45098, 8/10] Nowrap limits iterations - test cases Tom de Vries
2011-05-18 18:27 ` [PATCH PR45098, 9/10] Cheap shift-add Tom de Vries
2011-05-19 5:33 ` Zdenek Dvorak
2011-05-20 11:32 ` Tom de Vries
2011-05-20 20:09 ` Zdenek Dvorak
2011-05-21 15:05 ` Eric Botcazou
2011-05-22 19:33 ` Tom de Vries
2011-05-22 20:22 ` Richard Guenther
2011-05-22 21:11 ` Eric Botcazou
2011-05-17 10:03 ` [PATCH, PR45098, 9/10] Tom de Vries
2011-05-17 10:30 ` [PATCH, PR45098, 10/10] Tom de Vries
2011-05-18 18:30 ` [PATCH PR45098, 10/10] Cheap shift-add - test case Tom de Vries
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