[Bug fortran/19619] New: LAPACK optimisation error

["billingd at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>]

I have an LAPACK testuite failure with 20050124 gfortran on i686-pc-cygwin.

gcd.out has the failure
 CGV drivers: 64 out of   1092 tests failed to pass the threshold
with -O2 but not with -O0.

I have narrowed down the input file (below) to find a case that fails for a 
2x2 matrix.  I will work on isolating the bug and producing a self-contained 
test case.

To reproduce:
 - build LAPACK with -O2
 - ./xeigtstc <  cgd_bug.in > cgd_bug.out

####### cgd_bug.in #####
CGV               Data for the Complex Nonsymmetric Eigenvalue Driver
1                 Number of matrix dimensions
2                 Matrix dimensions  
1 1 1 2 1         Parameters NB, NBMIN, NXOVER, NS, NBCOL
10                Threshold for test ratios
.FALSE.           Put T to test the error exits
0                 Code to interpret the seed
CGV 26            Test all 26 matrix types

#### cgd_bug.out ###

 Tests of the Generalized Nonsymmetric Eigenvalue Problem Driver CGGEV

 LAPACK VERSION 3.0, released June 30, 1999 

 The following parameter values will be used:
    M:         2
    N:         2
    NB:        1
    NBMIN:     1
    NX:        1
    NS:        2
    MAXB:      1

 Relative machine underflow is taken to be    0.117549E-37
 Relative machine overflow  is taken to be    0.340282E+39
 Relative machine precision is taken to be    0.596046E-07

 Routines pass computational tests if test ratio is less than   10.00


 CGV -- Complex Generalized eigenvalue problem driver
 Matrix types (see CDRGEV for details): 
 Special Matrices:                       (J'=transposed Jordan block)
   1=(0,0)  2=(I,0)  3=(0,I)  4=(I,I)  5=(J',J')  6=(diag(J',I), diag(I,J'))
 Diagonal Matrices:  ( D=diag(0,1,2,...) )
   7=(D,I)   9=(large*D, small*I)  11=(large*I, small*D)  13=(large*D, large*I)
   8=(I,D)  10=(small*D, large*I)  12=(small*I, large*D)  14=(small*D, small*I)
  15=(D, reversed D)
 Matrices Rotated by Random Orthogonal Matrices U, V:
  16=Transposed Jordan Blocks             19=geometric alpha, beta=0,1
  17=arithm. alpha&beta                   20=arithmetic alpha, beta=0,1
  18=clustered alpha, beta=0,1            21=random alpha, beta=0,1
 Large & Small Matrices:
  22=(large, small)   23=(small,large)    24=(small,small)    25=(large,large)
  26=random O(1) matrices.

 Tests performed:    
 1 = max | ( b A - a B )'*l | / const.,
 2 = | |VR(i)| - 1 | / ulp,
 3 = max | ( b A - a B )*r | / const.
 4 = | |VL(i)| - 1 | / ulp,
 5 = 0 if W same no matter if r or l computed,
 6 = 0 if l same no matter if l computed,
 7 = 0 if r same no matter if r computed,
 
 Matrix order=    2, type=20, seed=1914,1677,3228,1473, result  5 is 8.389E+06
 Matrix order=    2, type=22, seed=2020,2295,3604,2829, result  5 is 8.389E+06
 Matrix order=    2, type=24, seed=3140, 353,1345, 653, result  5 is 8.389E+06
 Matrix order=    2, type=25, seed=3352,1849,3502,3661, result  5 is 8.389E+06
 Matrix order=    2, type=26, seed=2749,1691, 257,2573, result  5 is 8.389E+06
 CGV drivers:      5 out of    182 tests failed to pass the threshold

 -----------------------------------------------------------------------


 End of tests
 Total time used =         0.00 seconds

-- 
           Summary: LAPACK optimisation error
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: billingd at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-cygwin
  GCC host triplet: i686-pc-cygwin
GCC target triplet: i686-pc-cygwin
OtherBugsDependingO 5900
             nThis:


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19619