Re: Was: Debug optimized code; Now: How many compiler bugs have you seen?

Chris F Clark <cfc@shell01.TheWorld.com>
Thu, 25 Sep 2008 18:16:12 -0400

          From comp.compilers
Related articles
[4 earlier articles]
Was: Debug optimized code; Now: How many compiler bugs have you seen? cfc@shell01.TheWorld.com (Chris F Clark) (2008-09-24)
Re: Was: Debug optimized code; Now: How many compiler bugs have you se ArarghMail809@Arargh.com (2008-09-24)
Re: Was: Debug optimized code; Now: How many compiler bugs have you se n.pipenbrinck@cubic.org (Nils) (2008-09-25)
Re: Was: Debug optimized code; Now: How many compiler bugs have you se sh006d3592@blueyonder.co.uk (Stephen Horne) (2008-09-25)
Re: Was: Debug optimized code; Now: How many compiler bugs have you se gneuner2@comcast.net (George Neuner) (2008-09-25)
Re: Was: Debug optimized code; Now: How many compiler bugs have you se dot@dotat.at (Tony Finch) (2008-09-25)
Re: Was: Debug optimized code; Now: How many compiler bugs have you se cfc@shell01.TheWorld.com (Chris F Clark) (2008-09-25)
Re: Was: Debug optimized code; Now: How many compiler bugs have you se jfc@mit.edu (2008-10-02)
| List of all articles for this month |
From: Chris F Clark <cfc@shell01.TheWorld.com>
Newsgroups: comp.compilers
Date: Thu, 25 Sep 2008 18:16:12 -0400
Organization: The World Public Access UNIX, Brookline, MA
References: 08-09-076 08-09-105 08-09-110 08-09-115 08-09-119 08-09-124
Keywords: errors
Posted-Date: 26 Sep 2008 07:47:53 EDT

Talk about Karma, George Neuner wrote:
> Prime Pascal (circa 1986)
> - if the numeric labels of a case statement were sparsely
> distributed, the compiler would generate a kind of binary
> search through them. But if the labels were "too sparse", the
> search code would never match the last label.


That bug would have been mine. Some time in the 80's, I wrote the
part of the code generator/optimizer that generated switch tables and
binary searches for the Prime compilers, which included their Pascal
compiler. There probably was an off-by-one type of bug that caused it
to get the binary search wrong for very sparse cases.


Mea culpa,
-Chris


******************************************************************************
Chris Clark Internet: christopher.f.clark@compiler-resources.com
Compiler Resources, Inc. or: compres@world.std.com
23 Bailey Rd Web Site: http://world.std.com/~compres
Berlin, MA 01503 voice: (508) 435-5016
USA fax: (978) 838-0263 (24 hours)

Post a followup to this message

Return to the comp.compilers page.
Search the comp.compilers archives again.