[Bug middle-end/49310] [4.7 Regression] Compile time hog in var-tracking emit

[Joost.VandeVondele at pci dot uzh.ch]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49310

--- Comment #7 from Joost VandeVondele <Joost.VandeVondele at pci dot uzh.ch> 2011-06-09 06:54:33 UTC ---
two more datapoints (depth=30 is still running):

max-vartrack-expr-depth=22: var-tracking emit     :5459.44 (99%) usr
max-vartrack-expr-depth=25: var-tracking emit     :42078.07 (100%) usr

these are the timings for the various -Ox

'-g -O0 -fbounds-check' : 14s
'-g -O1 -fbounds-check' : 2631s
'   -O1 -fbounds-check' : 44s
'-g -O2 -fbounds-check' : 43s

from this point of view, something at -O2 seems to be very good at cleaning up
these very long expressions very cheaply. Would it make sense to run that pass
also at -O1 (maybe only when these long expressions are observed) ?