The following code shows the problem:
program test
common /abc/ mwkx(80)
dimension listpr(20),lisbit(10),lispat(8)
* This is badly compiled
* ======================
equivalence (listpr(10),lisbit(1),mwkx(10))
+, (listpr(10),lispat(1))
do i = 1,20
listpr(i) = 0
enddo
do i = 1,10
lisbit(i) = i
enddo
do j = 3,4
lisbit(j) = 0
enddo
print *, '======================================================'
print *, 'wrong result:'
print '(20i4)', listpr
call sub1
call sub2
stop
end
subroutine sub1
common /abc/ mwkx(80)
dimension listpr(20),lisbit(10),lispat(8)
* This is a workaround
* ====================
equivalence (listpr(10),lisbit(1)), (listpr(10),mwkx(10))
+, (listpr(10),lispat(1))
do i = 1,20
listpr(i) = 0
enddo
do i = 1,10
lisbit(i) = i
enddo
do j = 3,4
lisbit(j) = 0
enddo
print *, '======================================================'
print *, 'correct result:'
print '(20i4)', listpr
end
subroutine sub2
* This gives correct results
* ==========================
dimension mwkx(80)
dimension listpr(20),lisbit(10),lispat(8)
equivalence (listpr(10),lisbit(1),mwkx(10))
+, (listpr(10),lispat(1))
do i = 1,20
listpr(i) = 0
enddo
do i = 1,10
lisbit(i) = i
enddo
do j = 3,4
lisbit(j) = 0
enddo
print *, '======================================================'
print *, 'correct result (common replaced by dimension):'
print '(20i4)', listpr
end
This yields the following output:
======================================================
wrong result:
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0
======================================================
correct result:
0 0 0 0 0 0 0 0 0 1 2 0 0 5 6 7 8 9 10
0
======================================================
correct result (common replaced by dimension):
0 0 0 0 0 0 0 0 0 1 2 0 0 5 6 7 8 9 10
0
--
Summary: equivalence to common block array broken
Product: gcc
Version: 4.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: harald dot vogt at desy dot de
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25395
