https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86757
Bug ID: 86757
Summary: [og8,nvptx] gangprivate related regressions
Product: gcc
Version: 8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: cesar at gcc dot gnu.org
Target Milestone: ---
The goacc_parlevel patches have been backported to openacc-gcc-8-branch in git
revision 6781e2dd99. For the most part, the patches applied cleanly, however, I
had to xfail the following tests in libgomp.oacc-c-c++-common because they fail
with -O0:
loop-gwv-1.c
loop-red-gwv-1.c
loop-red-w-2.c
These tests work on trunk at -O0. I believe the problem was introduced with the
gangprivate patch. When I deactivated the gangprivate patch by modifying
nvptx.c:nvptx_goacc_expand_accel_var to always return NULL_RTX, those test
cases started passing.
I suspect this bug crept into og8 because those aforementioned tests were
originally skipped altogether at -O0 because they contained inline PTX assembly
code, which wasn't optimized away by the host compiler unless the program is
built with -O1 or greater. The goacc_parlevel changes replace the inline PTX
code with builtin functions that get expanded by the backend, which enables
those tests to run at -O0.
