https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109403
Bug ID: 109403
Summary: Alignment of common blocks not reported correctly
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: ipa
Assignee: unassigned at gcc dot gnu.org
Reporter: jahns at dkrz dot de
CC: marxin at gcc dot gnu.org
Target Milestone: ---
When compiling a source file with -flto, the alignment of common blocks seems
to not be reported from gcc-nm:
$ cat >align-test.f90 <<EOF
MODULE CONFTEST_ALIGN
USE, INTRINSIC :: ISO_C_BINDING, ONLY: C_INT
IMPLICIT NONE
INTEGER(C_INT), PUBLIC, &
BIND(c, name='align_test_variable') :: align_test_variable
END MODULE CONFTEST_ALIGN
EOF
$ gfortran -flto -O2 -c -o align-test.o align-test.f90
$ gcc-nm align-test.o
00000000 C align_test_variable
Expected value was 4 byte alignment, but any value other than 0 would be
acceptable as long as it matches what the resulting DSO or program later
contains.
I tested this initially with gfortran 11.1 and 11.2 on Linux x86_64 because
that's what I have readily available and what I'm most interested in.
An equivalent C source exhibits the same problem:
$ echo "int align_test_variable __attribute__((common));" \
| gcc -c -flto -x c - -o align-test-c.o
$ gcc-nm align-test-c.o
00000000 C align_test_variable
Since no one seems to have reported similar experiences I expect to still find
this problem in most recent compiler versions.
