[Bug tree-optimization/54027] [4.8 Regression] possible mis-optimization of signed left shift in c89 mode

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54027

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
           Keywords|                            |wrong-code
   Last reconfirmed|                            |2012-07-20
          Component|c                           |tree-optimization
         AssignedTo|unassigned at gcc dot       |rguenth at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1
            Summary|possible mis-optimization   |[4.8 Regression] possible
                   |of signed left shift in c89 |mis-optimization of signed
                   |mode                        |left shift in c89 mode
   Target Milestone|---                         |4.8.0

--- Comment #3 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-07-20 
09:37:54 UTC ---
Mine.  This is VRPs handling of left-shifts via the multiplication code.  I
didn't know this was implementation defined.