Richi reported occassional hangs with taskwait-depend-nowait-1.*
tests and I've finally manged to reproduce. The problem is if
taskwait depend without nowait is encountered soon after
taskwait depend nowait and the former depends on the latter and there
is no other work to do, the taskwait depend without nowait is put
to sleep, but the empty_task optimization in
gomp_task_run_post_handle_dependers wouldn't wake it up in that
case. gomp_task_run_post_handle_dependers normally does some wakeups
because it schedules more work (another task), which is not the
case of empty_task, but we need to do the wakeups that would be done
upon task completion so that we awake sleeping threads when the
last child is done.
So, the taskwait-depend-nowait-1.* testcase is fixed with the
else if (__builtin_expect (task->parent_depends_on, 0) part of
the patch.
The new testcase can hang on another problem, if the empty task
is the last task of a taskgroup, we need to use atomic store
like elsewhere to decrease the counter to 0, and wake up taskgroup
end if needed.
Yet another spot which can sleep is normal taskwait (without depend),
but I believe nothing needs to be done for that - in that case we
await solely until the children's queue has no tasks, tasks still
waiting for dependencies aren't accounted in that, but the reason
is that if taskwait should wait for something, there needs to be at least
one active child doing something (in the children queue), which then
possibly awakes some of its siblings when the dependencies are met,
or in the empty task case awakes further dependencies, but in any
case the child that finished is still handled as active child and
will awake taskwait at the end if there is nothing further to
do.
Last sleeping case are barriers, but that is handled by ++ret and
awaking the barrier.
2022-05-25 Jakub Jelinek <jakub@redhat.com>
* task.c (gomp_task_run_post_handle_dependers): If empty_task
is the last task taskwait depend depends on, wake it up.
Similarly if it is the last child of a taskgroup, use atomic
store instead of decrement and awak taskgroup wait if any.
* testsuite/libgomp.c-c++-common/taskwait-depend-nowait-2.c: New test.
This adds architecture options and multilibs for the AMD GFX90a GPUs.
It also tidies up some of the ISA selection code, and corrects a few small
mistake in the gfx908 naming.
gcc/ChangeLog:
* config.gcc (amdgcn): Accept --with-arch=gfx908 and gfx90a.
* config/gcn/gcn-opts.h (enum gcn_isa): New.
(TARGET_GCN3): Use enum gcn_isa.
(TARGET_GCN3_PLUS): Likewise.
(TARGET_GCN5): Likewise.
(TARGET_GCN5_PLUS): Likewise.
(TARGET_CDNA1): New.
(TARGET_CDNA1_PLUS): New.
(TARGET_CDNA2): New.
(TARGET_CDNA2_PLUS): New.
(TARGET_M0_LDS_LIMIT): New.
(TARGET_PACKED_WORK_ITEMS): New.
* config/gcn/gcn.cc (gcn_isa): Change to enum gcn_isa.
(gcn_option_override): Recognise CDNA ISA variants.
(gcn_omp_device_kind_arch_isa): Support gfx90a.
(gcn_expand_prologue): Make m0 init optional.
Add support for packed work items.
(output_file_start): Support gfx90a.
(gcn_hsa_declare_function_name): Support gfx90a metadata.
* config/gcn/gcn.h (TARGET_CPU_CPP_BUILTINS):Add __CDNA1__ and
__CDNA2__.
* config/gcn/gcn.md (<su>mulsi3_highpart): Use TARGET_GCN5_PLUS.
(<su>mulsi3_highpart_imm): Likewise.
(<su>mulsidi3): Likewise.
(<su>mulsidi3_imm): Likewise.
* config/gcn/gcn.opt (gpu_type): Add gfx90a.
* config/gcn/mkoffload.cc (EF_AMDGPU_MACH_AMDGCN_GFX90a): New.
(main): Support gfx90a.
* config/gcn/t-gcn-hsa: Add gfx90a multilib.
* config/gcn/t-omp-device: Add gfx90a isa.
libgomp/ChangeLog:
* plugin/plugin-gcn.c (EF_AMDGPU_MACH): Add
EF_AMDGPU_MACH_AMDGCN_GFX90a.
(gcn_gfx90a_s): New.
(isa_hsa_name): Support gfx90a.
(isa_code): Likewise.
This patch adds support for (so far C/C++)
#pragma omp taskwait nowait depend(...)
directive, which is like
#pragma omp task depend(...)
;
but slightly optimized on the library side, so that it creates
the task only for the purpose of dependency tracking and doesn't actually
schedule it and wait for it when the dependencies are satisfied, instead
makes its dependencies satisfied right away.
2022-05-24 Jakub Jelinek <jakub@redhat.com>
PR c/105378
gcc/
* omp-builtins.def (BUILT_IN_GOMP_TASKWAIT_DEPEND_NOWAIT): New
builtin.
* gimplify.cc (gimplify_omp_task): Diagnose taskwait with nowait
clause but no depend clauses.
* omp-expand.cc (expand_taskwait_call): Use
BUILT_IN_GOMP_TASKWAIT_DEPEND_NOWAIT rather than
BUILT_IN_GOMP_TASKWAIT_DEPEND if nowait clause is present.
gcc/c/
* c-parser.cc (OMP_TASKWAIT_CLAUSE_MASK): Add nowait clause.
gcc/cp/
* parser.cc (OMP_TASKWAIT_CLAUSE_MASK): Add nowait clause.
gcc/testsuite/
* c-c++-common/gomp/taskwait-depend-nowait-1.c: New test.
libgomp/
* libgomp_g.h (GOMP_taskwait_depend_nowait): Declare.
* libgomp.map (GOMP_taskwait_depend_nowait): Export at GOMP_5.1.1.
* task.c (empty_task): New function.
(gomp_task_run_post_handle_depend_hash): Declare earlier.
(gomp_task_run_post_handle_depend): Declare.
(GOMP_task): Optimize fn == empty_task if there is nothing to wait
for.
(gomp_task_run_post_handle_dependers): Optimize task->fn == empty_task.
(GOMP_taskwait_depend_nowait): New function.
* testsuite/libgomp.c-c++-common/taskwait-depend-nowait-1.c: New test.
For allocatable/pointer arrays, a firstprivate to a device
not only needs to privatize the descriptor but also the actual
data. This is implemented as:
firstprivate(x) firstprivate(x.data) attach(x [bias: &x.data-&x)
where the address of x in device memory is saved in hostaddrs[i]
by libgomp and the middle end actually passes hostaddrs[i]' to
attach.
As side effect, has_device_addr(array_desc) had to be changed:
before, it was converted to firstprivate in the front end; now
it is handled in omp-low.cc as has_device_addr requires a shallow
firstprivate (not touching the data pointer) while the normal
firstprivate requires (now) a deep firstprivate.
gcc/fortran/ChangeLog:
PR fortran/104949
* f95-lang.cc (LANG_HOOKS_OMP_ARRAY_SIZE): Redefine.
* trans-openmp.cc (gfc_omp_array_size): New.
(gfc_trans_omp_variable_list): Never turn has_device_addr
to firstprivate.
* trans.h (gfc_omp_array_size): New.
gcc/ChangeLog:
PR fortran/104949
* langhooks-def.h (lhd_omp_array_size): New.
(LANG_HOOKS_OMP_ARRAY_SIZE): Define.
(LANG_HOOKS_DECLS): Add it.
* langhooks.cc (lhd_omp_array_size): New.
* langhooks.h (struct lang_hooks_for_decls): Add hook.
* omp-low.cc (scan_sharing_clauses, lower_omp_target):
Handle GOMP_MAP_FIRSTPRIVATE for array descriptors.
libgomp/ChangeLog:
PR fortran/104949
* target.c (gomp_map_vars_internal, copy_firstprivate_data):
Support attach for GOMP_MAP_FIRSTPRIVATE.
* testsuite/libgomp.fortran/target-firstprivate-1.f90: New test.
* testsuite/libgomp.fortran/target-firstprivate-2.f90: New test.
* testsuite/libgomp.fortran/target-firstprivate-3.f90: New test.
This patch adds two new OpenMP runtime routines: omp_target_memcpy_async and
omp_target_memcpy_rect_async. Both functions are introduced in OpenMP 5.1 as
asynchronous variants of omp_target_memcpy and omp_target_memcpy_rect.
In contrast to the synchronous variants, the asynchronous functions have two
additional function parameters to allow the specification of task dependences:
int depobj_count
omp_depend_t *depobj_list
integer(c_int), value :: depobj_count
integer(omp_depend_kind), optional :: depobj_list(*)
The implementation splits the synchronous functions into two parts: (a) check
and (b) copy. Then (a) is used in the asynchronous functions for the sequential
part, and the actual copy process (b) is executed in a new created task. The
sequential part (a) takes into account the requirements for the return values:
"The routine returns zero if successful. Otherwise, it returns a non-zero
value." (omp_target_memcpy_async, OpenMP 5.1 spec, section 3.8.7)
"An application can determine the number of inclusive dimensions supported by an
implementation by passing NULL pointers (or C_NULL_PTR, for Fortran) for both
dst and src. The routine returns the number of dimensions supported by the
implementation for the specified device numbers. No copy operation is
performed." (omp_target_memcpy_rect_async, OpenMP 5.1 spec, section 3.8.8)
Due to asynchronicity an error is thrown if the asynchronous memcpy is not
successful (in contrast to the synchronous functions which use a return
value unequal to zero).
gcc/ChangeLog:
* omp-low.cc (omp_runtime_api_call): Added target_memcpy_async and
target_memcpy_rect_async to omp_runtime_apis array.
libgomp/ChangeLog:
* libgomp.map: Added omp_target_memcpy_async and
omp_target_memcpy_rect_async.
* libgomp.texi: Both functions are now supported.
* omp.h.in: Added omp_target_memcpy_async and
omp_target_memcpy_rect_async.
* omp_lib.f90.in: Added interfaces for both new functions.
* omp_lib.h.in: Likewise.
* target.c (ialias_redirect): Added for GOMP_task.
(omp_target_memcpy): Restructured into check and copy part.
(omp_target_memcpy_check): New helper function for omp_target_memcpy and
omp_target_memcpy_async that checks requirements.
(omp_target_memcpy_copy): New helper function for omp_target_memcpy and
omp_target_memcpy_async that performs the memcpy.
(omp_target_memcpy_async_helper): New helper function that is used in
omp_target_memcpy_async for the asynchronous task.
(omp_target_memcpy_async): Added.
(omp_target_memcpy_rect): Restructured into check and copy part.
(omp_target_memcpy_rect_check): New helper function for
omp_target_memcpy_rect and omp_target_memcpy_rect_async that checks
requirements.
(omp_target_memcpy_rect_copy): New helper function for
omp_target_memcpy_rect and omp_target_memcpy_rect_async that performs
the memcpy.
(omp_target_memcpy_rect_async_helper): New helper function that is used
in omp_target_memcpy_rect_async for the asynchronous task.
(omp_target_memcpy_rect_async): Added.
* task.c (ialias): Added for GOMP_task.
* testsuite/libgomp.c-c++-common/target-memcpy-async-1.c: New test.
* testsuite/libgomp.c-c++-common/target-memcpy-async-2.c: New test.
* testsuite/libgomp.c-c++-common/target-memcpy-rect-async-1.c: New test.
* testsuite/libgomp.c-c++-common/target-memcpy-rect-async-2.c: New test.
* testsuite/libgomp.fortran/target-memcpy-async-1.f90: New test.
* testsuite/libgomp.fortran/target-memcpy-async-2.f90: New test.
* testsuite/libgomp.fortran/target-memcpy-rect-async-1.f90: New test.
* testsuite/libgomp.fortran/target-memcpy-rect-async-2.f90: New test.
OpenMP 5.2 added
"When called from within a target region the effect is unspecified."
restriction to omp_display_env, so it is ok not to support it in
target regions (worst case we could add an empty implementation
or one with __builtin_trap in there).
2022-05-17 Jakub Jelinek <jakub@redhat.com>
* libgomp.texi (OpenMP 5.1): Remove "Not inside target regions"
comment for omp_display_env feature.
This patch adds support for inoutset depend-kind in depend
clauses. It is very similar to the in depend-kind in that
a task with a dependency with that depend-kind is dependent
on all previously created sibling tasks with matching address
unless they have the same depend-kind.
In the in depend-kind case everything is dependent except
for in -> in dependency, for inoutset everything is
dependent except for inoutset -> inoutset dependency.
mutexinoutset is also similar (everything is dependent except
for mutexinoutset -> mutexinoutset dependency), but there is
also the additional restriction that only one task with
mutexinoutset for each address can be scheduled at once (i.e.
mutual exclusitivty). For now we support mutexinoutset
the same as inout/out, but the inoutset support is full.
In order not to bump the ABI for dependencies each time
(we've bumped it already once, the old ABI supports only
inout/out and in depend-kind, the new ABI supports
inout/out, mutexinoutset, in and depobj), this patch arranges
for inoutset to be at least for the time being always handled
as if it was specified through depobj even when it is not.
So it uses the new ABI for that and inoutset are represented
like depobj - pointer to a pair of pointers where the first one
will be the actual address of the object mentioned in depend
clause and second pointer will be (void *) GOMP_DEPEND_INOUTSET.
2022-05-17 Jakub Jelinek <jakub@redhat.com>
gcc/
* tree-core.h (enum omp_clause_depend_kind): Add
OMP_CLAUSE_DEPEND_INOUTSET.
* tree-pretty-print.cc (dump_omp_clause): Handle
OMP_CLAUSE_DEPEND_INOUTSET.
* gimplify.cc (gimplify_omp_depend): Likewise.
* omp-low.cc (lower_depend_clauses): Likewise.
gcc/c-family/
* c-omp.cc (c_finish_omp_depobj): Handle
OMP_CLAUSE_DEPEND_INOUTSET.
gcc/c/
* c-parser.cc (c_parser_omp_clause_depend): Parse
inoutset depend-kind.
(c_parser_omp_depobj): Likewise.
gcc/cp/
* parser.cc (cp_parser_omp_clause_depend): Parse
inoutset depend-kind.
(cp_parser_omp_depobj): Likewise.
* cxx-pretty-print.cc (cxx_pretty_printer::statement): Handle
OMP_CLAUSE_DEPEND_INOUTSET.
gcc/testsuite/
* c-c++-common/gomp/all-memory-1.c (boo): Add test with
inoutset depend-kind.
* c-c++-common/gomp/all-memory-2.c (boo): Likewise.
* c-c++-common/gomp/depobj-1.c (f1): Likewise.
(f2): Adjusted expected diagnostics.
* g++.dg/gomp/depobj-1.C (f4): Adjust expected diagnostics.
include/
* gomp-constants.h (GOMP_DEPEND_INOUTSET): Define.
libgomp/
* libgomp.h (struct gomp_task_depend_entry): Change is_in type
from bool to unsigned char.
* task.c (gomp_task_handle_depend): Handle GOMP_DEPEND_INOUTSET.
Ignore dependencies where
task->depend[i].is_in && task->depend[i].is_in == ent->is_in
rather than just task->depend[i].is_in && ent->is_in. Remember
whether GOMP_DEPEND_IN loop is needed and guard the loop with that
conditional.
(gomp_task_maybe_wait_for_dependencies): Handle GOMP_DEPEND_INOUTSET.
Ignore dependencies where elem.is_in && elem.is_in == ent->is_in
rather than just elem.is_in && ent->is_in.
* testsuite/libgomp.c-c++-common/depend-1.c (test): Add task with
inoutset depend-kind.
* testsuite/libgomp.c-c++-common/depend-2.c (test): Likewise.
* testsuite/libgomp.c-c++-common/depend-3.c (test): Likewise.
* testsuite/libgomp.c-c++-common/depend-inoutset-1.c: New test.
This patch adds support for list items in the has_device_addr clause which type
is given by C++ template parameters.
gcc/cp/ChangeLog:
* pt.cc (tsubst_omp_clauses): Added OMP_CLAUSE_HAS_DEVICE_ADDR.
* semantics.cc (finish_omp_clauses): Added template decl processing.
libgomp/ChangeLog:
* testsuite/libgomp.c++/target-has-device-addr-7.C: New test.
* testsuite/libgomp.c++/target-has-device-addr-8.C: New test.
* testsuite/libgomp.c++/target-has-device-addr-9.C: New test.
For a non-descriptor array, map(A(n:m)) was mapped as
map(tofrom:A[n-1] [len: ...]) map(alloc:A [pointer assign, bias: ...])
with this patch, it is changed to
map(tofrom:A[n-1] [len: ...]) map(firstprivate:A [pointer assign, bias: ...])
The latter avoids an alloc - and also avoids the race condition with
nowait in the enclosed testcase. (Note: predantically, the testcase is
invalid since OpenMP 5.1, violating the map clause restriction at [354:10-13].
gcc/fortran/ChangeLog:
* trans-openmp.cc (gfc_trans_omp_clauses): When mapping nondescriptor
array sections, use GOMP_MAP_FIRSTPRIVATE_POINTER instead of
GOMP_MAP_POINTER for the pointer attachment.
libgomp/ChangeLog:
* testsuite/libgomp.fortran/target-nowait-array-section.f90: New test.
Including the GCC-shipped 'include/cuda/cuda.h' vs. system <cuda.h> and
'dlopen'ing the CUDA Driver library vs. linking it are separate concerns.
libgomp/
* plugin/Makefrag.am: Handle 'PLUGIN_NVPTX_DYNAMIC'.
* plugin/configfrag.ac (PLUGIN_NVPTX_DYNAMIC): Change
'AC_DEFINE_UNQUOTED' into 'AM_CONDITIONAL'.
* plugin/plugin-nvptx.c: Split 'PLUGIN_NVPTX_DYNAMIC' into
'PLUGIN_NVPTX_INCLUDE_SYSTEM_CUDA_H' and
'PLUGIN_NVPTX_LINK_LIBCUDA'.
* Makefile.in: Regenerate.
* config.h.in: Likewise.
* configure: Likewise.
The ugly part is that OpenMP 5.1 made omp_all_memory a reserved identifier
which isn't allowed to be used anywhere but in the depend clause, this is
against how everything else has been handled in OpenMP so far (where
some identifiers could have special meaning in some OpenMP clauses or
pragmas but not elsewhere).
The patch handles it by making it a conditional keyword (for -fopenmp
only) and emitting a better diagnostics when it is used in a primary
expression. Having a nicer diagnostics when e.g. trying to do
int omp_all_memory;
or
int *omp_all_memory[10];
etc. would mean changing too many spots and hooking into name lookups
to reject declaring any such symbols would be too ugly and I'm afraid
there are way too many spots where one can introduce a name
(variables, functions, namespaces, struct, enum, enumerators, template
arguments, ...).
Otherwise, the handling is quite simple, normal depend clauses lower
into addresses of variables being handed over to the library, for
omp_all_memory I'm using NULL pointers. omp_all_memory can only be
used with inout or out depend kinds and means that a task is dependent
on all previously created sibling tasks that have any dependency (of
any depend kind) and that any later created sibling tasks will be
dependent on it if they have any dependency.
2022-05-12 Jakub Jelinek <jakub@redhat.com>
gcc/
* gimplify.cc (gimplify_omp_depend): Don't build_fold_addr_expr
if null_pointer_node.
(gimplify_scan_omp_clauses): Likewise.
* tree-pretty-print.cc (dump_omp_clause): Print null_pointer_node
as omp_all_memory.
gcc/c-family/
* c-common.h (enum rid): Add RID_OMP_ALL_MEMORY.
* c-omp.cc (c_finish_omp_depobj): Don't build_fold_addr_expr
if null_pointer_node.
gcc/c/
* c-parser.cc (c_parse_init): Register omp_all_memory as keyword
if flag_openmp.
(c_parser_postfix_expression): Diagnose uses of omp_all_memory
in postfix expressions.
(c_parser_omp_variable_list): Handle omp_all_memory in depend
clause.
* c-typeck.cc (c_finish_omp_clauses): Handle omp_all_memory
keyword in depend clause as null_pointer_node, diagnose invalid
uses.
gcc/cp/
* lex.cc (init_reswords): Register omp_all_memory as keyword
if flag_openmp.
* parser.cc (cp_parser_primary_expression): Diagnose uses of
omp_all_memory in postfix expressions.
(cp_parser_omp_var_list_no_open): Handle omp_all_memory in depend
clause.
* semantics.cc (finish_omp_clauses): Handle omp_all_memory
keyword in depend clause as null_pointer_node, diagnose invalid
uses.
* pt.cc (tsubst_omp_clause_decl): Pass through omp_all_memory.
gcc/testsuite/
* c-c++-common/gomp/all-memory-1.c: New test.
* c-c++-common/gomp/all-memory-2.c: New test.
* c-c++-common/gomp/all-memory-3.c: New test.
* g++.dg/gomp/all-memory-1.C: New test.
* g++.dg/gomp/all-memory-2.C: New test.
libgomp/
* libgomp.h (struct gomp_task): Add depend_all_memory member.
* task.c (gomp_init_task): Initialize depend_all_memory.
(gomp_task_handle_depend): Handle omp_all_memory.
(gomp_task_run_post_handle_depend_hash): Clear
parent->depend_all_memory if equal to current task.
(gomp_task_maybe_wait_for_dependencies): Handle omp_all_memory.
* testsuite/libgomp.c-c++-common/depend-1.c: New test.
* testsuite/libgomp.c-c++-common/depend-2.c: New test.
* testsuite/libgomp.c-c++-common/depend-3.c: New test.
This is only active if GCC is 'configure'd with '--with-hsa-runtime=[...]' or
'--with-hsa-runtime-include=[...]', '--with-hsa-runtime-lib=[...]' -- which
nobody really is doing, as far as I can tell.
Originally changed for the libgomp HSA plugin in
commit b8d89b03db (r242749)
"Remove build dependence on HSA run-time", and later propagated into the GCN
plugin, these are no longer built against system-provided HSA Runtime library.
Instead, unconditionally built against the GCC-shipped 'include/hsa*.h' header
files, and at run time does 'dlopen("libhsa-runtime64.so.1")'. It thus doesn't
make sense to consider references to system-provided HSA Runtime library during
libgomp GCN plugin build.
libgomp/
* plugin/configfrag.ac (HSA_RUNTIME_CPPFLAGS)
(HSA_RUNTIME_LDFLAGS): Remove.
* configure: Regenerate.
This is only active if GCC is 'configure'd with '--with-hsa-runtime=[...]' or
'--with-hsa-runtime-lib=[...]' -- which nobody really is doing, as far as I can
tell.
'libgomp/testsuite/lib/libgomp.exp:libgomp_init' states:
# For build-tree testing, also consider the library paths used for builing.
# For installed testing, we assume all that to be provided in the sysroot.
if { $blddir != "" } {
[...]
global hsa_runtime_lib
if { $hsa_runtime_lib != "" } {
append always_ld_library_path ":$hsa_runtime_lib"
}
}
However, the libgomp GCN plugin is unconditionally built against the
GCC-shipped 'include/hsa*.h' header files, and at run time does
'dlopen("libhsa-runtime64.so.1")', so there is no system-provided HSA Runtime
library "used for builing". It thus doesn't make sense to amend
'LD_LIBRARY_PATH' for system-provided HSA Runtime library.
libgomp/
* testsuite/lib/libgomp.exp (libgomp_init): Don't
'append always_ld_library_path ":$hsa_runtime_lib"'.
* testsuite/libgomp-test-support.exp.in (hsa_runtime_lib): Don't set.
Fix-up for recent commit r13-116-g3f8c389fe90bf565a6221a46bb7fb745dd4c1510
"OpenMP: Fix use_device_{addr,ptr} with in-data-sharing arg", where we
currently get:
libgomp: use_device_ptr pointer wasn't mapped
FAIL: libgomp.fortran/use_device_addr-5.f90 -O execution test
libgomp/
* testsuite/libgomp.fortran/use_device_addr-5.f90: Fix up
multi-device testing.
While -foffload=-<flag> works (never documented legacy feature),
the documented way is to use -foffload-options=.
libgomp/ChangeLog:
* plugin/plugin-gcn.c (isa_matches_agent): Suggest -foffload-options.
For array-descriptor vars, the descriptor is assigned to a temporary. However,
this failed when the clause's argument was in turn in a data-sharing clause
as the outer context's VALUE_EXPR wasn't used.
gcc/ChangeLog:
* omp-low.cc (lower_omp_target): Fix use_device_{addr,ptr} with list
item that is in an outer data-sharing clause.
libgomp/ChangeLog:
* testsuite/libgomp.fortran/use_device_addr-5.f90: New test.
Last fall I've changed struct gomp_work_share, so that it doesn't have
__attribute__((aligned (64))) lock member in the middle unless the target has
non-emulated aligned allocator, otherwise it just makes sure the first and
second halves are 64 bytes appart for cache line reasons, but doesn't make
the struct 64-byte aligned itself and so we can use normal allocators for it.
When the struct isn't 64-byte aligned, the amount of tail padding significantly
decreases, to 0 or 4 bytes or so. The library uses that tail padding when
the ordered_teams_ids array (array of uints) and/or the memory for lastprivate
conditional temporaries (the latter wants to guarantee long long alignment).
The problem with it on ia32 darwin9 is that while the struct contains
long long members, long long is just 4 byte aligned while __alignof__(long long)
is 8. That causes problems in gomp_init_work_share, where we currently rely on
if offsetof (struct gomp_work_share, inline_ordered_team_ids) is long long
aligned, then that tail array will be aligned at runtime and so no extra
memory for dynamic realignment will be needed (that is false when the whole
struct doesn't have long long alignment). And also in the remaining hunks
causes another problem, where we compute INLINE_ORDERED_TEAM_IDS_OFF
as the above offsetof aligned up to long long boundary and subtract
sizeof (struct gomp_work_share) and INLINE_ORDERED_TEAM_IDS_OFF.
When unlucky, the former isn't multiple of 8 and the latter is 4 bigger
than that and as the subtraction is done in size_t, we end up with (size_t) -4,
so the comparison doesn't really work.
The fixes add additional conditions to make it work properly, but all of them
should be evaluated at compile time when optimizing and so shouldn't slow
anything.
2022-04-26 Jakub Jelinek <jakub@redhat.com>
PR libgomp/105358
* work.c (gomp_init_work_share): Don't mask of adjustment for
dynamic long long realignment if struct gomp_work_share has smaller
alignof than long long.
* loop.c (GOMP_loop_start): Don't use inline_ordered_team_ids if
struct gomp_work_share has smaller alignof than long long or if
sizeof (struct gomp_work_share) is smaller than
INLINE_ORDERED_TEAM_IDS_OFF.
* loop_ull.c (GOMP_loop_ull_start): Likewise.
* sections.c (GOMP_sections2_start): Likewise.
Tobias Burnus
GCC Administrator
Jakub Jelinek
Andrew Stubbs
Marcel Vollweiler
Thomas Schwinge
Sandra Loosemore