The Operation 2*i with short integers (KIND=3, KIND=6) give incorrect values if
the result exeeds the definded range for this types. The program example
compiled with
g77 test.f
give the following results:
integer*1: 100+100=-56, 2*100=200
integer*2: 20000+20000=-25536, 2*20000=40000
The second one of each line ist mathematical correct, but outside the valid
range of the data type.
Test System was a Redhat Linux 4 Enterprise on Dual Opteron
gcc-Version 3.4.3 20041212 (Red Hat 3.4.3-9.EL4)
Also seen with gcc 3.3.1 on Suse Linux 9.1 on Pentium M, and with
cygwin gcc 3.3.3 on Xeon System.
program short_int_test
implicit none
integer*1 i1
integer*2 i2
i1=100
print*, i1+i1, 2*i1
i2=20000
print*, i2+i2, 2*i2
end
--
Summary: false arithmetic with short integers
Product: gcc
Version: 3.4.3
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: fortran
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: ralph dot doering at web dot de
CC: gcc-bugs at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20473
