Bug 17097 - Large DATA initialization terminally slow
Summary: Large DATA initialization terminally slow
Status: RESOLVED DUPLICATE of bug 13465
Alias: None
Product: gcc
Classification: Unclassified
Component: fortran (show other bugs)
Version: 4.0.0
: P2 normal
Target Milestone: ---
Assignee: Not yet assigned to anyone
URL:
Keywords: compile-time-hog, monitored
Depends on:
Blocks:
 
Reported: 2004-08-19 10:23 UTC by Richard Henderson
Modified: 2004-08-19 14:13 UTC (History)
2 users (show)

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Host:
Target:
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Known to work:
Known to fail:
Last reconfirmed: 2004-08-19 11:36:53

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Description Richard Henderson 2004-08-19 10:23:48 UTC 
The following fragment

      PROGRAM APSI
      IMPLICIT DOUBLE PRECISION (A-H, O-Z)
      DIMENSION WORK(1200000)
      DATA WORK/1200000*0.0D0/
      END

does not compile in under 7.5 hours.  I have no idea how long it does take,
as I stopped the process.
Comment 1 Volker Reichelt 2004-08-19 11:36:49 UTC 
Confirmed.

Here are some timings. The first column is the array length:
4000:    1.0s
5000:    2.1s
6000:    3.5s
7000:    5.0s
8000:    7.0s
9000:    9.0s
10000:  11.5s
11000:  14.0s
12000:  17.0s

This is worse than quadratic! Only assuming quadratic behavior, the original
example would take about 2 days on my machine.
Comment 2 Andrew Pinski 2004-08-19 14:13:57 UTC 

*** This bug has been marked as a duplicate of 13465 ***
Comment 3 Toon Moene 2004-08-19 19:45:51 UTC 
Subject: Re:  Large DATA initialization terminally slow

pinskia at gcc dot gnu dot org wrote:

> ------- Additional Comments From pinskia at gcc dot gnu dot org  2004-08-19 14:13 -------
> 
> 
> *** This bug has been marked as a duplicate of 13465 ***
> 

Indeed, and - Andrew - I'd pedantically add: It's dupe, dammit - if you 
want Slashdot, you know where to find it !