With gfortran 20050129 I get a testsuite failure at -O2 that I don't see at -
O0. The failure is in the CGT tests in ctest.in:
CGT: General tridiagonal
Matrix types (1-6 have specified condition numbers):
1. Diagonal 7. Random, unspecified CNDNUM
2. Random, CNDNUM = 2 8. First column zero
3. Random, CNDNUM = sqrt(0.1/EPS) 9. Last column zero
4. Random, CNDNUM = 0.1/EPS 10. Last n/2 columns zero
5. Scaled near underflow 11. Scaled near underflow
6. Scaled near overflow 12. Scaled near overflow
Test ratios:
1: norm( L * U - A ) / ( N * norm(A) * EPS )
2: norm( B - A * X ) / ( norm(A) * norm(X) * EPS )
3: norm( X - XACT ) / ( norm(XACT) * CNDNUM * EPS )
4: norm( X - XACT ) / ( norm(XACT) * CNDNUM * EPS ), refined
5: norm( X - XACT ) / ( norm(XACT) * (error bound) )
6: (backward error) / EPS
7: RCOND * CNDNUM - 1.0
Messages:
NORM ='O', N = 1, type 5, test( 7) = 0.16777E+08
NORM ='I', N = 1, type 5, test( 7) = 0.16777E+08
TRANS='N', N = 1, NRHS= 1, type 5, test( 3) =
I have reduced it to the miscompilation of routine cgtts2.f at -O2. I have
isolated a single failing case, but if I try to change the routine the problem
evaporates.
Attached is:
- driv.f: a small driver program
- cgtts2.f: the LAPACK routine with the problem.
To reproduce:
gfortran -o pass.exe -O0 driv.f cgtts2.f
gfortran -o fail.exe -O0 driv.f cgtts2.f
./pass
B(1,1) = ( 4.0564819E+31, 0.000000 )
./fail
At line 15 of file driv.f
Internal Error: printf is broken
B(1,1) = (
Note: The internal error is PR 19363
--
Summary: optimization problem with LAPACK routine cgtts2.f
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
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19693
