Hi!
On 1/13/23 16:38, Jakub Jelinek wrote:
On Wed, Jan 11, 2023 at 03:18:06PM +0100, Christophe Lyon via Gcc-patches wrote:
While working on enabling DFP for AArch64, I noticed new failures in
gcc.dg/compat/struct-layout-1.exp (t028) which were not actually
caused by DFP types handling. These tests are generated during 'make
check' and enabling DFP made generation different (not sure if new
non-DFP tests are generated, or if existing ones are generated
differently, the tests in question are huge and difficult to compare).
Anyway, I reduced the problem to what I attach at the end of the new
gcc.target/aarch64/aapcs64/va_arg-17.c test and rewrote it in the same
scheme as other va_arg* AArch64 tests. Richard Sandiford further
reduced this to a non-vararg function, added as a second testcase.
This is a tough case mixing bit-fields and alignment, where
aarch64_function_arg_alignment did not follow what its descriptive
comment says: we want to use the natural alignment of the bit-field
type only if the user didn't reduce the alignment for the bit-field
itself.
The patch also adds a comment and assert that would help someone who
has to look at this area again.
The fix would be very small, except that this introduces a new ABI
break, and we have to warn about that. Since this actually fixes a
problem introduced in GCC 9.1, we keep the old computation to detect
when we now behave differently.
This patch adds two new tests (va_arg-17.c and
pr105549.c). va_arg-17.c contains the reduced offending testcase from
struct-layout-1.exp for reference. We update some tests introduced by
the previous patch, where parameters with bit-fields and packed
attribute now emit a different warning.
I'm seeing
+FAIL: g++.target/aarch64/bitfield-abi-warning-align16-O2.C
scan-assembler-times and\\tw0, w1, 1 10
+FAIL: g++.target/aarch64/bitfield-abi-warning-align32-O2.C
scan-assembler-times and\\tw0, w1, 1 10
+FAIL: g++.target/aarch64/bitfield-abi-warning-align8-O2.C scan-assembler-times
and\\tw0, w0, 1 11
+FAIL: g++.target/aarch64/bitfield-abi-warning-align8-O2.C scan-assembler-times
and\\tw0, w1, 1 18
+FAIL: gcc.target/aarch64/sve/pcs/struct_3_128.c -march=armv8.2-a+sve (internal
compiler error: in aarch64_layout_arg, at config/aarch64/aarch64.cc:7696)
+FAIL: gcc.target/aarch64/sve/pcs/struct_3_128.c -march=armv8.2-a+sve (test for
excess errors)
+FAIL: gcc.target/aarch64/sve/pcs/struct_3_256.c -march=armv8.2-a+sve (internal
compiler error: in aarch64_layout_arg, at config/aarch64/aarch64.cc:7696)
+FAIL: gcc.target/aarch64/sve/pcs/struct_3_256.c -march=armv8.2-a+sve (test for
excess errors)
+FAIL: gcc.target/aarch64/sve/pcs/struct_3_512.c -march=armv8.2-a+sve (internal
compiler error: in aarch64_layout_arg, at config/aarch64/aarch64.cc:7696)
+FAIL: gcc.target/aarch64/sve/pcs/struct_3_512.c -march=armv8.2-a+sve (test for
excess errors)
regressions with this change.
Really deeply sorry for this :-(
aarch64.cc:7696 is for me the newly added:
+ gcc_assert (alignment <= 16 * BITS_PER_UNIT
+ && (!alignment || abi_break < alignment)
+ && (!abi_break_packed || alignment < abi_break_packed));
assert.
Details in
https://kojipkgs.fedoraproject.org//work/tasks/2857/96062857/build.log
(configure line etc.), plus if you
wget https://kojipkgs.fedoraproject.org//work/tasks/2857/96062857/build.log
sed -n '/^begin /,/^end/p' build.log | uuencode > you get a compressed tarball
with the testsuite *.log files.
Thanks I managed to download this (you meant uudecode rather than
uuencode ;-) )
I see the scan-assembler-times are also failing in gcc.target, I guess
you just forgot to paste them?
From your other message, it seems you are building with stack-protector
enabled by default, but I can't see that in the configure lines?
Indeed I just checked the generated code with/without
-fstack-protector-all, and it obviously changes a lot, thus breaking the
fragile scan-assembler directives. As you said, it's easy to avoid with
-fno-stack-protector.
I'll check the problem with the assert.
Thanks and sorry,
Christophe
Jakub
