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[Bug rtl-optimization/17088] New: poor optimisation at -O2/3 and -fnew-ra


GNU F95 version 3.5.0 20040818 (experimental) (i686-pc-linux-gnu)
        compiled by GNU C version 3.5.0 20040818 (experimental).

the attached program (generated code to perform small matrix multiply) 
illustrates interesting behaviour. The third number printed is the timing of 
the MULT subroutine and is the one of interest (the other times the MATMUL 
built-in and the first measures the numerical error).

ifc -O2 test.f90               : 0.38 ! reference
gfortran -O1 test.f90          : 0.26 ! nice, faster than intel
gfortran -O2 test.f90          : 0.50 ! 2x slower than -O1
gfortran -O3 test.f90          : 0.50 ! idem
gfortran -O2 -fnew-ra test.f90 : 7.78 ! 30x slower than -O1

I have no idea what the magical switch would be to good code at e.g. -O2

-- 
           Summary: poor optimisation at -O2/3 and -fnew-ra
           Product: gcc
           Version: 3.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: rtl-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jv244 at cam dot ac dot uk
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17088


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