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From: "Dave Korn" <dave DOT korn AT artimi DOT com>
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Subject: RE: gcc bug
Date: Wed, 21 Nov 2007 15:57:15 -0000
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On 21 November 2007 15:43, Samuel Thibault wrote:

> Ok, so cygwin has it too. It's fixed in HEAD, see
>
http://www.nabble.com/-Bug-c-34130---New%3A-the-builtin-abs%28%29-gives-wrong-
result-when-used-in-some-expression-tf4824981.html#a13808833

  Now why didn't you just say "PR34130" in the first place?  Yep, fixed on
HEAD certainly wouldn't mean "fixed in a couple of years' old release
version"!

  Interesting:

http://gcc.gnu.org/viewcvs/trunk/gcc/fold-const.c?view=log&pathrev=130258

Revision 91373 - (view) (download) - [select for diffs]
Modified Sat Nov 27 10:13:56 2004 UTC (2 years, 11 months ago) by jakub
File length: 352911 byte(s)
Diff to previous 91170 (colored)

	* fold-const.c (extract_muldiv_1) <case ABS_EXPR>: If ctype is
	unsigned and type signed, build ABS_EXPR with signed_type (ctype)
	and only afterwards convert to ctype.


  That's probably where it got introduced.  I could always backport the fix to
3.4.4 and spin a fresh release, and to be fair, I wasn't planning to, but
that's a scary enough bug that I feel like I want to.

    cheers,
      DaveK
-- 
Can't think of a witty .sigline today....


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