Compiling with -O is 30 times slower than with -Onot

[simonpj]

This is a performance bug. In 6.8.1, compiling Serge's DoCon package, the "DoCon test" does build under -O and -O2, but it builds 30 times slower that under -Onot. As a result: install.txt recommends -Onot for "making" the test.

The following two points are not bugs, but maybe, need investigation, I do not know.

• The size of the .a library for docon under -O remains almost 3/2 larger than in 6.6.1.
• -O remains a little better than -O2 for `making' docon, -O2 does not increase the code performance for docon.

All this can be reproduced by downloading

 http://www.botik.ru/pub/local/Mechveliani/docon/2.11-pre/

Serge

[simonpj]

See also #783, #1136

[simonpj]

Fixed at last

Wed Sep  3 13:02:28 BST 2008  simonpj@microsoft.com
  * Major change in compilation of instance declarations (fix Trac #955, #2328)

I'm assuming this is the same as #955, #2328.

Simon