http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55888
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> 2013-01-07
10:45:37 UTC ---
(gdb) call debug_bitmap_set (set)
debug[0] := { message_7(D) (0007), rv_26 (0024), _30 (0034), {plus_expr,i_62,1}
(0021), vntemp_50 (0044), {convert_expr,vntemp_50} (0069) }
but value_expressions[44] only contains len_31.
So the question is where we added vntemp_50 (well, the bisect shows us where).
This is a VN value-number created for an expression that might need to be
inserted somewhere ((const size_t) _41). We fail to add that to its value.
Alternatively we fail to do the valueization "properly" when translating
an SSA_NAME.
In fact as original the valueization after PHI-translating SSA names looks
superfluous. The fix for PR55862 probably simply made us prune sth from
the antic set which resolved the oscillation.
Back to the drawing-board for PR55862 ...
