Opened 12 years ago

Closed 11 years ago

Last modified 10 years ago

#1875 closed bug (fixed)

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

Reported by: simonpj Owned by:
Priority: normal Milestone: 6.10.1
Component: Compiler Version: 6.8.1
Keywords: performance Cc:
Operating System: Unknown/Multiple Architecture: Unknown/Multiple
Type of failure: Compile-time performance bug Test Case:
Blocked By: Blocking:
Related Tickets: Differential Rev(s):
Wiki Page:

Description

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

Change History (8)

comment:1 Changed 12 years ago by simonpj

See also #783, #1136

comment:2 Changed 12 years ago by igloo

Keywords: performance added

comment:3 Changed 12 years ago by simonmar

Type: bugcompile-time performance bug

comment:4 Changed 11 years ago by igloo

Milestone: 6.8.36.10.1

comment:5 Changed 11 years ago by simonpj

Resolution: fixed
Status: newclosed

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

comment:6 Changed 11 years ago by simonmar

Architecture: UnknownUnknown/Multiple

comment:7 Changed 11 years ago by simonmar

Operating System: UnknownUnknown/Multiple

comment:8 Changed 10 years ago by simonmar

Type of failure: Compile-time performance bug
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