[tree-ssa] Mainline merge plan

[law@redhat.com]

In message <404422B7.6080404@specifixinc.com>, Jim Wilson writes:
 >Al Stone wrote:
 >> Probably true.  Mainline has not bootstrapped on
 >> ia64 for a couple of weeks; the day job has been
 >
 >I am not aware of any lingering bootstrap problem, and messages to the 
 >gcc-testresults mailing list seem to confirm that.  There is a 
 >successful report on Feb 27.
 >
 >I did an update and bootstrap today, and it did fail.  I tracked it down 
 >to a problem in global.c.  The list of registers to allocate had two of 
 >them swapped.  This is presumably a problem with allocno_compare, which 
 >does some FP arithmetic.  I see Steve Ellcey checked in a patch which 
 >enabled inline FP divides by default.  If I disable that (by changing 
 >TARGET_DEFAULT), then the bootstrap succeeds.
 >
 >So the inline FP divide code is somehow causing allocno_compare in 
 >global.c to be miscompiled.  I haven't had a chance to look at why yet.
FWIW, one of the allocators has an unstable sort when presented with a
small number of qtys to allocate.  That may (or may not) be related.

jeff