View mode: basic / threaded / horizontal-split · Log in · Help
November 14, 2010
Compiler optimization breaks multi-threaded code
There is one question on SO which seems like a serious problem for atomic 
ops.

http://stackoverflow.com/questions/4165149/compiler-optimization-breaks-
multi-threaded-code

in short:

shared uint cnt;
void atomicInc  ( ) { uint o; while ( !cas( &cnt, o, o + 1 ) ) o = cnt; }

is compile with dmd -O to something like:

shared uint cnt;
void atomicInc  ( ) { while ( !cas( &cnt, cnt, cnt + 1 ) ) { } }

see the web page for details.
November 14, 2010
Re: Compiler optimization breaks multi-threaded code
On Sunday 14 November 2010 01:04:46 Michal Minich wrote:
> There is one question on SO which seems like a serious problem for atomic
> ops.
> 
> http://stackoverflow.com/questions/4165149/compiler-optimization-breaks-
> multi-threaded-code
> 
> in short:
> 
> shared uint cnt;
> void atomicInc  ( ) { uint o; while ( !cas( &cnt, o, o + 1 ) ) o = cnt; }
> 
> is compile with dmd -O to something like:
> 
> shared uint cnt;
> void atomicInc  ( ) { while ( !cas( &cnt, cnt, cnt + 1 ) ) { } }
> 
> see the web page for details.

Please repost this to the D list and/or create bug report: 
http://d.puremagic.com/issues/enter_bug.cgi?product=D

The Bugs list is not for posting to. It's for the bug tracker to send updates 
to. You sign up for it if you want to receive those updates, not to post 
information on bugs.

- Jonathan M Davis
Top | Discussion index | About this forum | D home