On 7/10/25 4:41 AM, Gopi Kumar Bulusu wrote:
namaskaaram
Hi Gopi!
Please find the patch attached. This addresses regression for MicroBlaze
(PR118280)
Neal Frager posted a different patch (or an RFC) to address pr118280 on
7/1/25: https://www.mail-archive.com/gcc-patches@gcc.gnu.org/msg376017.html
The patches are different. Is your patch a replacement for Neal's?
Can you either reconcile the differences or tell me which patch is
correct or better?
You might also update the PR with this patch and a comment.
pr118280 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118280
Atomic support enhanced to fix existing atomic_compare_and_swapsi pattern
to handle side effects; new patterns atomic_fetch_op and atomic_test_and_set
added. As MicroBlaze has no QImode test/set instruction, use shift magic
to implement atomic_test_and_set. Make -mxl-barrel-shift the default to keep
the default atomics code tight.
Include the PR which is resolved in the patch comments.
I'm not quite sure what you mean by "keep the default atomics code tight".
Neal suggested making -mxl-barrel-shift default for linux, but not
default for bare-metal. This might be better for backward
compatibility, but depends on whether there are any MB configurations
which do not include a barrel shifter. If someone does have a MB config
without a barrel shifter and tries to recompile after this patch, it's
possible that invalid code would be silently generated.
Files Changed
* gcc/config/microblaze/iterators.md: New
* microblaze-protos.h/microblaze.cc : Add microblaze_subword_address
* gcc/config/microblaze/microblaze.md: constants: Add UNSPECV_CAS_BOOL,
UNSPECV_CAS_MEM, UNSPECV_CAS_VAL, UNSPECV_ATOMIC_FETCH_OP
type: add atomic
* gcc/config/microblaze/microblaze.h: TARGET_DEFAULT : Add MASK_BARREL_SHIFT
* gcc/config/microblaze/sync.md: Add atomic_fetch_<atomic_optab>si
atomic_test_and_set
Target Checked
microblazeel-amd-linux
Testing
deja-g++
=== g++ Summary ===
# of expected passes 237906
# of unexpected failures 4165
# of unexpected successes 3
# of expected failures 2180
# of unresolved testcases 645
# of unsupported tests 2658
deja-libstdcpp
=== libstdc++ Summary ===
# of expected passes 18180
# of unexpected failures 311
# of expected failures 133
# of unresolved testcases 18
# of unsupported tests 853
Includes Test case 29_atomics/atomic_flag/clear/1.cc (which checks for
atomic_test_and_set)
I don't have a baseline to compare these test results with, or test
results before applying this patch, so the results don't have any
meaning to me. Was the test case 29 failing before applying the patch
and succeeding after? Were there any other differences?
Neal indicated that patch was tested using buildroot with
target=microblazeel-buildroot-linux-gnu. It looks like you have
target=microblazeel-amd-linux. How are you running the test suite?
--
Michael Eager
