patch to fix PR55342

[Vladimir Makarov <vmakarov at redhat dot com>]

  The following patch solves

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55342

  LRA after spilling a pseudo tries to assign freed hard regno to other 
reload pseudos and chooses the best.  The more reload pseudos got the 
freed hard regno, the less cost of spilling.  But the reload pseudos 
could get another hard regno without spilling.  So LRA code before the 
patch incorrectly evaluated the cost of spilling.  The patch tries to 
allocate a hard reg to the other reload pseudos before and after 
spilling in order to correctly evaluate spilling cost.

  The patch was successfully bootstrapped on x86/x86-64.

  Committed as rev. 193588.

2012-11-17  Vladimir Makarov  <vmakarov@redhat.com>

        PR rtl-optimization/55342
        * lra-assigns.c (spill_for): Try to allocate other reload pseudos
        before and after spilling.

Attachment: pr55342.patch
Description: Text document