http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46703
Summary: Wrong I/O output (only) when running under valgrind
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: fortran
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: bur...@gcc.gnu.org
CC: jvdeli...@gcc.gnu.org
There is something odd with the following program. It shows (here) always the
correct output -- except I run it through valgrind.
(The program is from
http://groups.google.com/group/comp.lang.fortran/msg/cb8e13e6226bc6c5 (part of
the c.l.f thread
http://groups.google.com/group/comp.lang.fortran/browse_thread/thread/1b907e3b7b6f3461).
James reports that it fails on MinGW with the www.equation.com version but not
with the MinGW version.)
Without valgrind, the program prints (with GCC 4.6 and 4.5 and any optimization
level):
3.36210314311209350626E-4912
...
3.36210314311209350626E-4912
1.18973149535723176502E+4932
...
1.18973149535723176502E+4932
However, using valgrind I get:
0.0000000000000000000
...
0.0000000000000000000
i.f E+0000
...
i.f E+0000
But otherwise no warning and no leakage.
Using GCC 4.5, I get with valgrind "0.0000" and "+Infinity".
The issue seems to be in libgfortran as the result depends on the library and
not on the FE compiler. I am also not sure whether there is a real issue or
whether it is just a side effect of valgrind.
program bugs2
implicit none
integer, parameter :: ep = 10
real(ep) x
integer i
x = tiny(x)
write(*,*) x
do i = 1, 10
x = 100*x
write(*,*) x
end do
x = huge(x)
write(*,*) x
do i = 1, 10
x = x/1.0e100_ep
write(*,*) x
end do
end program bugs2
