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s390{,x} ABI incompatibility between gcc 4.0 and 4.1
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Ulrich Weigand <uweigand at de dot ibm dot com>, Joern RENNECKE <joern dot rennecke at st dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: Mon, 28 Nov 2005 09:49:23 -0500
- Subject: s390{,x} ABI incompatibility between gcc 4.0 and 4.1
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
Hi!
There are several g*dg/compat/ tests failing that show ABI
incompatibilities:
FAIL: tmpdir-g++.dg-struct-layout-1/t024 cp_compat_x_tst.o-cp_compat_y_alt.o execute
FAIL: tmpdir-g++.dg-struct-layout-1/t024 cp_compat_x_alt.o-cp_compat_y_tst.o execute
FAIL: tmpdir-g++.dg-struct-layout-1/t026 cp_compat_x_tst.o-cp_compat_y_alt.o execute
FAIL: tmpdir-g++.dg-struct-layout-1/t026 cp_compat_x_alt.o-cp_compat_y_tst.o execute
FAIL: tmpdir-g++.dg-struct-layout-1/t027 cp_compat_x_tst.o-cp_compat_y_alt.o execute
FAIL: tmpdir-g++.dg-struct-layout-1/t027 cp_compat_x_alt.o-cp_compat_y_tst.o execute
FAIL: tmpdir-g++.dg-struct-layout-1/t028 cp_compat_x_tst.o-cp_compat_y_alt.o execute
FAIL: tmpdir-g++.dg-struct-layout-1/t028 cp_compat_x_alt.o-cp_compat_y_tst.o execute
FAIL: tmpdir-gcc.dg-struct-layout-1/t025 c_compat_x_tst.o-c_compat_y_alt.o execute
FAIL: tmpdir-gcc.dg-struct-layout-1/t025 c_compat_x_alt.o-c_compat_y_tst.o execute
FAIL: tmpdir-gcc.dg-struct-layout-1/t027 c_compat_x_tst.o-c_compat_y_alt.o execute
FAIL: tmpdir-gcc.dg-struct-layout-1/t027 c_compat_x_alt.o-c_compat_y_tst.o execute
FAIL: tmpdir-gcc.dg-struct-layout-1/t028 c_compat_x_tst.o-c_compat_y_alt.o execute
FAIL: tmpdir-gcc.dg-struct-layout-1/t028 c_compat_x_alt.o-c_compat_y_tst.o execute
I have looked just at one failure, but maybe all of them are the same thing.
typedef char __attribute__((vector_size (16))) v16qi;
int i = __alignof__ (v16qi);
with GCC 4.0 sets i to 8 (s390{,x} have BIGGEST_ALIGNMENT 64), but
GCC 4.1 sets i to 16.
The changes that created this binary incompatibility are
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23467
I think. layout_type sets TYPE_ALIGN to 128 bits (size of v16qi)
and in 4.0 and earlier finalize_type_size used to decrease the size
to GET_MODE_ALIGNMENT (TImode), which is 64 on s390{,x}.
Was this change intentional? If yes, I think it should be documented in 4.1
release notes, but I still hope it wasn't intentional.
Jakub