From 001ab12e620c6f117b2e93c77d188bd62fe7ba03 Mon Sep 17 00:00:00 2001 From: Frederik Harwath Date: Thu, 13 Feb 2020 07:30:16 +0100 Subject: [PATCH] openmp: ignore nowait if async execution is unsupported [PR93481] An OpenMP "nowait" clause on a target construct currently leads to a call to GOMP_OFFLOAD_async_run in the plugin that is used for offloading at execution time. The nvptx plugin contains only a stub of this function that always produces a fatal error if called. This commit changes the "nowait" implementation to ignore the clause if the executing device's plugin does not implement GOMP_OFFLOAD_async_run. The stub in the nvptx plugin is removed which effectively means that programs containing "nowait" can now be executed with nvptx offloading as if the clause had not been used. This behavior is consistent with the OpenMP specification which says that "[...] execution of the target task *may* be deferred" (emphasis added), cf. OpenMP 5.0, page 172. libgomp/ * plugin/plugin-nvptx.c: Remove GOMP_OFFLOAD_async_run stub. * target.c (gomp_load_plugin_for_device): Make "async_run" loading optional. (gomp_target_task_fn): Assert "devicep->async_run_func". (clear_unsupported_flags): New function to remove unsupported flags (right now only GOMP_TARGET_FLAG_NOWAIT) that can be be ignored. (GOMP_target_ext): Apply clear_unsupported_flags to flags. * testsuite/libgomp.c/target-33.c: Remove xfail for offload_target_nvptx. * testsuite/libgomp.c/target-34.c: Likewise. --- libgomp/plugin/plugin-nvptx.c | 7 +------ libgomp/target.c | 15 ++++++++++++++- libgomp/testsuite/libgomp.c/target-33.c | 3 --- libgomp/testsuite/libgomp.c/target-34.c | 3 --- 4 files changed, 15 insertions(+), 13 deletions(-) diff --git a/libgomp/plugin/plugin-nvptx.c b/libgomp/plugin/plugin-nvptx.c index 6033c71..ec103a2 100644 --- a/libgomp/plugin/plugin-nvptx.c +++ b/libgomp/plugin/plugin-nvptx.c @@ -1931,9 +1931,4 @@ GOMP_OFFLOAD_run (int ord, void *tgt_fn, void *tgt_vars, void **args) nvptx_stacks_free (stacks, teams * threads); } -void -GOMP_OFFLOAD_async_run (int ord, void *tgt_fn, void *tgt_vars, void **args, - void *async_data) -{ - GOMP_PLUGIN_fatal ("GOMP_OFFLOAD_async_run unimplemented"); -} +/* TODO: Implement GOMP_OFFLOAD_async_run. */ diff --git a/libgomp/target.c b/libgomp/target.c index 3df0072..0ff727d 100644 --- a/libgomp/target.c +++ b/libgomp/target.c @@ -2022,6 +2022,16 @@ GOMP_target (int device, void (*fn) (void *), const void *unused, gomp_unmap_vars (tgt_vars, true); } +static inline unsigned int +clear_unsupported_flags (struct gomp_device_descr *devicep, unsigned int flags) +{ + /* If we cannot run asynchronously, simply ignore nowait. */ + if (devicep != NULL && devicep->async_run_func == NULL) + flags &= ~GOMP_TARGET_FLAG_NOWAIT; + + return flags; +} + /* Like GOMP_target, but KINDS is 16-bit, UNUSED is no longer present, and several arguments have been added: FLAGS is a bitmask, see GOMP_TARGET_FLAG_* in gomp-constants.h. @@ -2054,6 +2064,8 @@ GOMP_target_ext (int device, void (*fn) (void *), size_t mapnum, size_t tgt_align = 0, tgt_size = 0; bool fpc_done = false; + flags = clear_unsupported_flags (devicep, flags); + if (flags & GOMP_TARGET_FLAG_NOWAIT) { struct gomp_thread *thr = gomp_thread (); @@ -2524,6 +2536,7 @@ gomp_target_task_fn (void *data) } ttask->state = GOMP_TARGET_TASK_READY_TO_RUN; + assert (devicep->async_run_func); devicep->async_run_func (devicep->target_id, fn_addr, actual_arguments, ttask->args, (void *) ttask); return true; @@ -3040,7 +3053,7 @@ gomp_load_plugin_for_device (struct gomp_device_descr *device, if (device->capabilities & GOMP_OFFLOAD_CAP_OPENMP_400) { DLSYM (run); - DLSYM (async_run); + DLSYM_OPT (async_run, async_run); DLSYM_OPT (can_run, can_run); DLSYM (dev2dev); } diff --git a/libgomp/testsuite/libgomp.c/target-33.c b/libgomp/testsuite/libgomp.c/target-33.c index 15d2d7e..1bed4b6 100644 --- a/libgomp/testsuite/libgomp.c/target-33.c +++ b/libgomp/testsuite/libgomp.c/target-33.c @@ -1,6 +1,3 @@ -/* { dg-xfail-run-if "GOMP_OFFLOAD_async_run not implemented" { offload_target_nvptx } } - Cf. https://gcc.gnu.org/PR81688. */ - extern void abort (void); int diff --git a/libgomp/testsuite/libgomp.c/target-34.c b/libgomp/testsuite/libgomp.c/target-34.c index 5a35964..66d9f54 100644 --- a/libgomp/testsuite/libgomp.c/target-34.c +++ b/libgomp/testsuite/libgomp.c/target-34.c @@ -1,6 +1,3 @@ -/* { dg-xfail-run-if "GOMP_OFFLOAD_async_run not implemented" { offload_target_nvptx } } - Cf. https://gcc.gnu.org/PR81688. */ - extern void abort (void); int -- 2.7.4