[Bug c++/68023] 4.8.4 generates good code where 5.2 generates bad code

2015-10-20 Thread paolo.carlini at oracle dot com 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68023

Paolo Carlini  changed:

   What|Removed |Added

 Status|UNCONFIRMED |WAITING
   Last reconfirmed||2015-10-20
 Ever confirmed|0   |1

[Bug c++/68023] 4.8.4 generates good code where 5.2 generates bad code

2015-10-20 Thread barto at cambridgesemantics dot com 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68023

David Barto  changed:

   What|Removed |Added

 Status|WAITING |RESOLVED
 Resolution|--- |WONTFIX

--- Comment #5 from David Barto  ---
The code uses so many un-aligned access operations (legal in x86 code) that
using -fsanitize=undefined causes the code to stop execution very early in the
startup.

If, after fixing this, the problem still exists, I'll be back to re-open the
bug.

[Bug c++/68023] 4.8.4 generates good code where 5.2 generates bad code

2015-10-20 Thread trippels at gcc dot gnu.org 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68023

Markus Trippelsdorf  changed:

   What|Removed |Added

 CC||trippels at gcc dot gnu.org

--- Comment #4 from Markus Trippelsdorf  ---
Could you please provide a simple standalone testcase that shows the issue?

You may also compile your code with -fsanitize=undefined and see if
anything pops up at runtime.

[Bug c++/68023] 4.8.4 generates good code where 5.2 generates bad code

2015-10-19 Thread barto at cambridgesemantics dot com 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68023

--- Comment #3 from David Barto  ---
Created attachment 36546
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36546&action=edit
Compressed gcc 5.2 output

[Bug c++/68023] 4.8.4 generates good code where 5.2 generates bad code

2015-10-19 Thread barto at cambridgesemantics dot com 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68023

--- Comment #2 from David Barto  ---
Created attachment 36545
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36545&action=edit
compressed gcc 4.8 output

[Bug c++/68023] 4.8.4 generates good code where 5.2 generates bad code

2015-10-19 Thread barto at cambridgesemantics dot com 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68023

--- Comment #1 from David Barto  ---
Created attachment 36544
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36544&action=edit
Configuration for GCC 5.2