[Bug fortran/50327] New: [4.7 Regression] Front-end optimization generates wrong code for BLAS's srotmg

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50327

             Bug #: 50327
           Summary: [4.7 Regression] Front-end optimization generates
                    wrong code for BLAS's srotmg
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: major
          Priority: P3
         Component: fortran
        AssignedTo: unassig...@gcc.gnu.org
        ReportedBy: bur...@gcc.gnu.org
                CC: tkoe...@gcc.gnu.org


Created attachment 25227
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25227
Netlib BLAS's srotmg.f  (== lapack-3.3.1/BLAS/SRC/srotmg.f)

Compiling BLAS' srotmg.f with -ffrontend-optimize causes an endless loop:

$ gfortran -ffrontend-optimize  -c srotmg.f; gfortran -O0 test.f90 srotmg.o \
  && ./a.out
  CALLING: SROTMG

Without, it works:

$ gfortran -fno-frontend-optimize  -c srotmg.f; gfortran -O0 test.f90 srotmg.o
\
  && ./a.out
  CALLING: SROTMG
  DONE CALLING: SROTMG


FAILING: 2011-09-08, 2011-08-25-r178053, 05-28-r174379, 2011-05-10, 
WORKING: 2010-09-28-r164677  (with -O3, -ffrontend-optimize didn't exist yet)
Seemingly also working: Current 4.6 branch.


implicit none
real DTEMP(9)
EXTERNAL          SROTMG
DTEMP(1) = 2.00000003E-10
DTEMP(2) = 3.99999991E-02
DTEMP(3) = 100000.000
DTEMP(4) = 10.0000000
DTEMP(5) = 0.00000000
WRITE (*,*)' CALLING: SROTMG'
CALL SROTMG(DTEMP(1),DTEMP(2),DTEMP(3),DTEMP(4),DTEMP(5))
WRITE (*,*)' DONE CALLING: SROTMG'
end