Currently, this is a rather useless patch - even though it helps to reduce
the number of local patches I have. Due to the printed sorry, adding a
testcase with -fdump-tree-* is also not possible, yet.
For reverse offload, the plan is to call
GOMP_target_ext
inside the on the device, passing
'device(omp_initial_device)'
alias device(GOMP_DEVICE_HOST_FALLBACK) to the
target device's libgomp.
The pointer to the generated target-region function is then
passed as argument. However, that only works if that function
is not nullified ...
The reason that nullifying was added is:
https://gcc.gnu.org/PR100573
https://gcc.gnu.org/r12-1066-g95d67762171f83277a5700b270c0d1e2756f83f4
https://gcc.gnu.org/pipermail/gcc-patches/2021-May/571285.html
Note: Instead of just checking for GOMP_DEVICE_HOST_FALLBACK,
more effort could be done, e.g. by setting some attribute on the
generated function and then check for check for it. Example:
'omp target device_ancestor' + using lookup_attribute).
That's what's done in the second variant.
OK for mainline (which variant)? Or do you prefer to wait for
a more complete patch?
Tobias
PS: Reverse offload - still to do:
- 'requires' patch
- Generate two variants of the target-region function:
an empty version on the device (just to have a pointer address
in the offload_func table) and the full version (on the host only)
Those together are sufficient for a omp_get_num_device() == 0 version
(implied by 'required reverse_offload' not being fulfilled by any device).
For a more useful implementation, more work inside libgomp is required.
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OpenMP: Prepare omp-* for ancestor:1 handling
gcc/ChangeLog:
* omp-expand.cc (expand_omp_target): Set device to
GOMP_DEVICE_HOST_FALLBACK for ancestor.
* omp-offload.cc (pass_omp_target_link::execute): Don't
nullify function pointer for ancestor:1.
gcc/omp-expand.cc | 6 +++++-
gcc/omp-offload.cc | 4 ++++
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/gcc/omp-expand.cc b/gcc/omp-expand.cc
index 1023c56fc3d..dc0a963e9e3 100644
--- a/gcc/omp-expand.cc
+++ b/gcc/omp-expand.cc
@@ -10005,7 +10005,11 @@ expand_omp_target (struct omp_region *region)
need_device_adjustment = true;
device_loc = OMP_CLAUSE_LOCATION (c);
if (OMP_CLAUSE_DEVICE_ANCESTOR (c))
- sorry_at (device_loc, "%<ancestor%> not yet supported");
+ {
+ device = build_int_cst (integer_type_node,
+ GOMP_DEVICE_HOST_FALLBACK);
+ sorry_at (device_loc, "%<ancestor%> not yet supported");
+ }
}
else
{
diff --git a/gcc/omp-offload.cc b/gcc/omp-offload.cc
index 3a89119371c..d72c1ac23f3 100644
--- a/gcc/omp-offload.cc
+++ b/gcc/omp-offload.cc
@@ -2803,6 +2803,10 @@ pass_omp_target_link::execute (function *fun)
{
if (gimple_call_builtin_p (gsi_stmt (gsi), BUILT_IN_GOMP_TARGET))
{
+ tree dev = gimple_call_arg (gsi_stmt (gsi), 0);
+ if (TREE_CODE (dev) == INTEGER_CST
+ && wi::to_wide (dev) == GOMP_DEVICE_HOST_FALLBACK)
+ continue; /* ancestor:1 */
/* Nullify the second argument of __builtin_GOMP_target_ext. */
gimple_call_set_arg (gsi_stmt (gsi), 1, null_pointer_node);
update_stmt (gsi_stmt (gsi));
OpenMP: Prepare omp-* for ancestor:1 handling
gcc/ChangeLog:
* omp-expand.cc (expand_omp_target): Set device to
GOMP_DEVICE_HOST_FALLBACK for ancestor.
* omp-low.cc (scan_omp_target): Add 'omp target device_ancestor'
attribute to generated target-region function for ancestor:1.
* omp-offload.cc (pass_omp_target_link::execute): Don't nullify
function pointer for ancestor:1.
gcc/omp-expand.cc | 6 +++++-
gcc/omp-low.cc | 6 ++++++
gcc/omp-offload.cc | 9 +++++++++
3 files changed, 20 insertions(+), 1 deletion(-)
diff --git a/gcc/omp-expand.cc b/gcc/omp-expand.cc
index 1023c56fc3d..dc0a963e9e3 100644
--- a/gcc/omp-expand.cc
+++ b/gcc/omp-expand.cc
@@ -10005,7 +10005,11 @@ expand_omp_target (struct omp_region *region)
need_device_adjustment = true;
device_loc = OMP_CLAUSE_LOCATION (c);
if (OMP_CLAUSE_DEVICE_ANCESTOR (c))
- sorry_at (device_loc, "%<ancestor%> not yet supported");
+ {
+ device = build_int_cst (integer_type_node,
+ GOMP_DEVICE_HOST_FALLBACK);
+ sorry_at (device_loc, "%<ancestor%> not yet supported");
+ }
}
else
{
diff --git a/gcc/omp-low.cc b/gcc/omp-low.cc
index b9d5529f212..140ef229cc0 100644
--- a/gcc/omp-low.cc
+++ b/gcc/omp-low.cc
@@ -3094,6 +3094,12 @@ scan_omp_target (gomp_target *stmt, omp_context *outer_ctx)
if (offloaded)
{
create_omp_child_function (ctx, false);
+ tree c = omp_find_clause (gimple_omp_target_clauses (ctx->stmt),
+ OMP_CLAUSE_DEVICE);
+ if (c && OMP_CLAUSE_DEVICE_ANCESTOR (c))
+ DECL_ATTRIBUTES (ctx->cb.dst_fn)
+ = tree_cons (get_identifier ("omp target device_ancestor"),
+ NULL_TREE, DECL_ATTRIBUTES (ctx->cb.dst_fn));
gimple_omp_target_set_child_fn (stmt, ctx->cb.dst_fn);
}
diff --git a/gcc/omp-offload.cc b/gcc/omp-offload.cc
index 3a89119371c..a6c108aef30 100644
--- a/gcc/omp-offload.cc
+++ b/gcc/omp-offload.cc
@@ -2803,6 +2803,15 @@ pass_omp_target_link::execute (function *fun)
{
if (gimple_call_builtin_p (gsi_stmt (gsi), BUILT_IN_GOMP_TARGET))
{
+ tree dev = gimple_call_arg (gsi_stmt (gsi), 0);
+ tree fn = gimple_call_arg (gsi_stmt (gsi), 1);
+ if (POINTER_TYPE_P (TREE_TYPE (fn)))
+ fn = TREE_OPERAND (fn, 0);
+ if (TREE_CODE (dev) == INTEGER_CST
+ && wi::to_wide (dev) == GOMP_DEVICE_HOST_FALLBACK
+ && lookup_attribute ("omp target device_ancestor",
+ DECL_ATTRIBUTES (fn)) != NULL_TREE)
+ continue; /* ancestor:1 */
/* Nullify the second argument of __builtin_GOMP_target_ext. */
gimple_call_set_arg (gsi_stmt (gsi), 1, null_pointer_node);
update_stmt (gsi_stmt (gsi));
