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* [Bug tree-optimization/10520] induction variable analysis not used to eliminate comparisons
[not found] <bug-10520-4@http.gcc.gnu.org/bugzilla/>
@ 2014-03-13 11:05 ` rguenth at gcc dot gnu.org
2022-01-05 23:39 ` pinskia at gcc dot gnu.org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: rguenth at gcc dot gnu.org @ 2014-03-13 11:05 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10520
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
First of all number-of-iteration analysis would need to figure out that
the vars don't overflow ... (thus that the loop terminates). It cannot
even compute the number of iterations symbolically.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/10520] induction variable analysis not used to eliminate comparisons
[not found] <bug-10520-4@http.gcc.gnu.org/bugzilla/>
2014-03-13 11:05 ` [Bug tree-optimization/10520] induction variable analysis not used to eliminate comparisons rguenth at gcc dot gnu.org
@ 2022-01-05 23:39 ` pinskia at gcc dot gnu.org
2022-01-05 23:45 ` pinskia at gcc dot gnu.org
2023-02-18 4:10 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-01-05 23:39 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=10520
--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Here is the current IR at optimized:
<bb 3> [local count: 958878296]:
# n_in_42 = PHI <n_in_31(4), 0(2)>
# n_out_43 = PHI <n_out_32(4), 0(2)>
# n_in1_44 = PHI <n_in1_33(4), 1(2)>
# n_out1_45 = PHI <n_out1_34(4), 1(2)>
n_in.0_1 = (int) n_in_42;
_3 = n_in.0_1 w* 4;
_4 = buf_fast_28(D) + _3;
n_out.1_5 = (int) n_out_43;
_7 = n_out.1_5 w* 4;
_8 = buf_fast_28(D) + _7;
_9 = *_4;
*_8 = _9;
n_in1.2_10 = (int) n_in1_44;
_12 = n_in1.2_10 w* 4;
_13 = buf_fast_28(D) + _12;
n_out1.3_14 = (int) n_out1_45;
_16 = n_out1.3_14 w* 4;
_17 = buf_fast_28(D) + _16;
_18 = *_13;
*_17 = _18;
n_in_31 = n_in_42 + 4;
n_out_32 = n_out_43 + 2;
n_in1_33 = n_in1_44 + 4;
n_out1_34 = n_out1_45 + 2;
_24 = MAX_EXPR <n_in_31, n_out_32>;
if (_24 < _tmp0_27(D))
goto <bb 4>; [94.50%]
else
goto <bb 5>; [5.50%]
<bb 4> [local count: 906139990]:
_25 = MAX_EXPR <n_in1_33, n_out1_34>;
if (_25 < _tmp0_27(D))
goto <bb 3>; [94.50%]
else
goto <bb 5>; [5.50%]
We should figure out that:
_24 = MAX_EXPR <n_in_31, n_out_32>;
Is just as n_in_31 is being incremented by 4 each time through the loop while
n_out_32 only by 2
_24 = n_in_31
And:
_25 = MAX_EXPR <n_in1_33, n_out1_34>;
Is just (same logic as above)
_25 = n_in1_33
And then we have:
if (n_in_31 < _tmp0_27(D))
goto <bb 4>; [94.50%]
else
goto <bb 5>; [5.50%]
<bb 4> [local count: 906139990]:
if (n_in1_33 < _tmp0_27(D))
goto <bb 3>; [94.50%]
else
goto <bb 5>; [5.50%]
Where n_in1_33 = n_in_31+1
There for we should reduce it to just:
<bb 4> [local count: 906139990]:
if (n_in1_33 < _tmp0_27(D))
goto <bb 3>; [94.50%]
else
goto <bb 5>; [5.50%]
(hopefully I did this correctly).
Of course this depends on if they are not going to be overflowed .... Which we
know they won't because they are being used for pointer accesses.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/10520] induction variable analysis not used to eliminate comparisons
[not found] <bug-10520-4@http.gcc.gnu.org/bugzilla/>
2014-03-13 11:05 ` [Bug tree-optimization/10520] induction variable analysis not used to eliminate comparisons rguenth at gcc dot gnu.org
2022-01-05 23:39 ` pinskia at gcc dot gnu.org
@ 2022-01-05 23:45 ` pinskia at gcc dot gnu.org
2023-02-18 4:10 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-01-05 23:45 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=10520
--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Hmm, shouldn't we convert:
_24 = MAX_EXPR <n_in_31, n_out_32>;
if (_24 < _tmp0_27(D))
goto <bb 4>; [94.50%]
else
goto <bb 5>; [5.50%]
<bb 4> [local count: 906139990]:
_25 = MAX_EXPR <n_in1_33, n_out1_34>;
if (_25 < _tmp0_27(D))
goto <bb 3>; [94.50%]
else
goto <bb 5>; [5.50%]
Which is:
if (MAX_EXPR <n_in_31, n_out_32> < _tmp0_27 && MAX_EXPR <n_in1_33, n_out1_34> <
_tmp0_27) goto 3 else goto 5
Into:
if (MAX_EXPR<MAX_EXPR <n_in_31, n_out_32>, MAX_EXPR <n_in1_33, n_out1_34> > <
_tmp0_27) goto 3 else goto 5
Also? To simplify things a little more?
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/10520] induction variable analysis not used to eliminate comparisons
[not found] <bug-10520-4@http.gcc.gnu.org/bugzilla/>
` (2 preceding siblings ...)
2022-01-05 23:45 ` pinskia at gcc dot gnu.org
@ 2023-02-18 4:10 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-02-18 4:10 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=10520
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
See Also| |https://gcc.gnu.org/bugzill
| |a/show_bug.cgi?id=108841
--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #6)
> Also? To simplify things a little more?
I filed PR 108841 for that.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/10520] induction variable analysis not used to eliminate comparisons
[not found] <20030428130601.10520.bsamwel@xs4all.nl>
@ 2004-08-09 2:07 ` pinskia at gcc dot gnu dot org
0 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2004-08-09 2:07 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2004-08-09 02:07 -------
There is some hope for this to be done as there is some code on the LNO branch to do it but it is not
fully done yet.
--
What |Removed |Added
----------------------------------------------------------------------------
Component|rtl-optimization |tree-optimization
Last reconfirmed|2004-05-10 16:38:29 |2004-08-09 02:07:55
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10520
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2023-02-18 4:10 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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[not found] <bug-10520-4@http.gcc.gnu.org/bugzilla/>
2014-03-13 11:05 ` [Bug tree-optimization/10520] induction variable analysis not used to eliminate comparisons rguenth at gcc dot gnu.org
2022-01-05 23:39 ` pinskia at gcc dot gnu.org
2022-01-05 23:45 ` pinskia at gcc dot gnu.org
2023-02-18 4:10 ` pinskia at gcc dot gnu.org
[not found] <20030428130601.10520.bsamwel@xs4all.nl>
2004-08-09 2:07 ` pinskia at gcc dot gnu dot org
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