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From: "tnfchris at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/114932] Improvement in CHREC can give large performance gains
Date: Fri, 03 May 2024 08:09:53 +0000	[thread overview]
Message-ID: <bug-114932-4-SLkVgcTm3V@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-114932-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114932

--- Comment #3 from Tamar Christina <tnfchris at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #2)
> > which is harder for prefetchers to follow.
> 
> This seems like a limitation in the HW prefetcher rather than anything else.
> Maybe the cost model for addressing mode should punish base+index if so.
> Many HW prefetchers I know of are based on the final VA (or even PA) rather
> looking at the instruction to see if it increments or not ...

That was the first thing we tried, and even increasing the cost of
register_offset to something ridiculously high doesn't change a thing.

IVopts thinks it needs to use it and generates:

  _1150 = (voidD.26 *) _1148;
  _1152 = (sizetype) l0_78(D);
  _1154 = _1152 * 324;
  _1156 = _1154 + 216;
  # VUSE <.MEM_421>
  vect__349.614_1418 = MEM <vector(2) integer(kind=4)D.9> [(integer(kind=4)D.9
*)_1150 + _1156 * 1 clique 2 base 0];

Hence the bug report to see what's going on.

  parent reply	other threads:[~2024-05-03  8:09 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-05-03  5:51 [Bug tree-optimization/114932] New: " tnfchris at gcc dot gnu.org
2024-05-03  6:26 ` [Bug tree-optimization/114932] " rguenth at gcc dot gnu.org
2024-05-03  7:03 ` pinskia at gcc dot gnu.org
2024-05-03  8:09 ` tnfchris at gcc dot gnu.org [this message]
2024-05-03  8:41 ` tnfchris at gcc dot gnu.org
2024-05-03  8:44 ` tnfchris at gcc dot gnu.org
2024-05-03  8:45 ` tnfchris at gcc dot gnu.org
2024-05-03  9:12 ` rguenth at gcc dot gnu.org
2024-05-13  8:28 ` tnfchris at gcc dot gnu.org
2024-06-05  9:42 ` [Bug tree-optimization/114932] IVopts inefficient handling of signed IV used for addressing tnfchris at gcc dot gnu.org
2024-06-05 10:23 ` rguenth at gcc dot gnu.org
2024-06-05 19:02 ` tnfchris at gcc dot gnu.org
2024-06-06  6:17 ` rguenther at suse dot de
2024-06-06  6:40 ` tnfchris at gcc dot gnu.org
2024-06-06  7:55 ` rguenther at suse dot de
2024-06-06  8:01 ` tnfchris at gcc dot gnu.org

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