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Subject: [Bug rtl-optimization/51821] [4.5/4.6/4.7 Regression] 64bit > 32bit conversion produces incorrect results with optimizations
Date: Wed, 11 Jan 2012 22:03:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51821

Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
         AssignedTo|unassigned at gcc dot       |ebotcazou at gcc dot
                   |gnu.org                     |gnu.org

--- Comment #7 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2012-01-11 22:03:16 UTC ---
> RTL infrastructure bug, adding some CCs that might find it interesting.

Ugh.  The problem is that the df_simulate_* routines don't correctly handle
hard registers.  Oddly enough, there is an isolated use of hard_regno_nregs in
the df_simulate_one_insn_forwards routine, but with no comment whatsoever.

We need to do something, but the impact of the change isn't very clear.