[Bug middle-end/55585] New: compile time hog at -O1 -fboundscheck -g

Joost.VandeVondele at mat dot ethz.ch gcc-bugzilla@gcc.gnu.org
Tue Dec 4 08:22:00 GMT 2012


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55585

             Bug #: 55585
           Summary: compile time hog at -O1 -fboundscheck -g
    Classification: Unclassified
           Product: gcc
           Version: 4.7.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: Joost.VandeVondele@mat.ethz.ch


Created attachment 28870
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28870
gzipped testcase

With 4.4.6 the following timings are seen:

time /usr/bin/gfortran -c -O0 slow.f90 
real    0m2.299s
time /usr/bin/gfortran -c -O1 -fbounds-check slow.f90 
real    0m16.560s
time /usr/bin/gfortran -c -g -O2 -fbounds-check slow.f90 
real    0m32.841s


With 4.7 I see significant slowdowns at -O1 -fbounds-check, being extreme with
-g

time gfortran -c -O0 slow.f90 
real    0m3.355s
time gfortran -c -O1 -fbounds-check slow.f90 
real    0m43.057s
time gfortran -c -g -O1 -fbounds-check slow.f90 
real    3m42.117s
time gfortran -c -g -O2 -fbounds-check  slow.f90 
real    0m20.102s


I wonder if whatever pass makes -O2 so fast should not be implied at -O1
-fbounds-check.



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