[Patch] libstdc++/21172

[Paolo Carlini]

Hi,

the below is my best try at fixing this long standing issue. Apparently, 
the performance impact is minimal, because already at tree-level it's 
clear that (__len - 1) / 2 is computed only once before the main loop. 
Also, division by two is certainly cheap.

I'm taking the occasion to fix a few minor issues in the file: most 
puzzling a couple of commented out __glibcxx_requires_heap: I'm CC-ing 
Doug, in case he has any insight, otherwise, given succesuful tests with 
_GLIBCXX_DEBUG defined, I'm assuming a trivial typo.

Tested x86-linux, will wait until tomorrow.

Paolo.

///////////////////
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: CL_21172_2
URL: <http://gcc.gnu.org/pipermail/libstdc++/attachments/20070211/7f2b5b22/attachment.ksh>
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: patch_21172_2
URL: <http://gcc.gnu.org/pipermail/libstdc++/attachments/20070211/7f2b5b22/attachment-0001.ksh>