[mlir][OpenMP] allow cancellation to not be directly nested #134084
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omp.cancel and omp.cancellationpoint contain an attribute describing the
type of parent construct which should be cancelled. e.g.
```
!$omp cancel do
```
Must be inside of a wsloop. Previously the verifer required the
immediate parent to be this operation. This is not quite right because
something like the following is valid:
```
!$omp parallel do
do i = 1, N
if (cond) then
!$omp cancel do
endif
enddo
```
This patch relaxes the verifier to only require that some parent
operation matches (not necessarily the immediate parent).
|
@llvm/pr-subscribers-mlir-openmp @llvm/pr-subscribers-flang-openmp Author: Tom Eccles (tblah) Changesomp.cancel and omp.cancellationpoint contain an attribute describing the type of parent construct which should be cancelled. e.g. Must be inside of a wsloop. Previously the verifer required the immediate parent to be this operation. This is not quite right because something like the following is valid: This patch relaxes the verifier to only require that some parent operation matches (not necessarily the immediate parent). Full diff: https://github.com/llvm/llvm-project/pull/134084.diff 2 Files Affected:
diff --git a/mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp b/mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp
index 882bc4071482f..e45d6d9fb3831 100644
--- a/mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp
+++ b/mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp
@@ -3103,22 +3103,15 @@ void CancelOp::build(OpBuilder &builder, OperationState &state,
LogicalResult CancelOp::verify() {
ClauseCancellationConstructType cct = getCancelDirective();
- Operation *parentOp = (*this)->getParentOp();
-
- if (!parentOp) {
- return emitOpError() << "must be used within a region supporting "
- "cancel directive";
- }
+ Operation *thisOp = (*this).getOperation();
if ((cct == ClauseCancellationConstructType::Parallel) &&
- !isa<ParallelOp>(parentOp)) {
+ !thisOp->getParentOfType<ParallelOp>()) {
return emitOpError() << "cancel parallel must appear "
<< "inside a parallel region";
}
if (cct == ClauseCancellationConstructType::Loop) {
- auto loopOp = dyn_cast<LoopNestOp>(parentOp);
- auto wsloopOp = llvm::dyn_cast_if_present<WsloopOp>(
- loopOp ? loopOp->getParentOp() : nullptr);
+ auto wsloopOp = thisOp->getParentOfType<WsloopOp>();
if (!wsloopOp) {
return emitOpError()
@@ -3134,12 +3127,12 @@ LogicalResult CancelOp::verify() {
}
} else if (cct == ClauseCancellationConstructType::Sections) {
- if (!(isa<SectionsOp>(parentOp) || isa<SectionOp>(parentOp))) {
+ auto sectionsOp = thisOp->getParentOfType<SectionsOp>();
+ if (!sectionsOp) {
return emitOpError() << "cancel sections must appear "
<< "inside a sections region";
}
- if (isa_and_nonnull<SectionsOp>(parentOp->getParentOp()) &&
- cast<SectionsOp>(parentOp->getParentOp()).getNowaitAttr()) {
+ if (sectionsOp.getNowait()) {
return emitError() << "A sections construct that is canceled "
<< "must not have a nowait clause";
}
@@ -3159,25 +3152,20 @@ void CancellationPointOp::build(OpBuilder &builder, OperationState &state,
LogicalResult CancellationPointOp::verify() {
ClauseCancellationConstructType cct = getCancelDirective();
- Operation *parentOp = (*this)->getParentOp();
-
- if (!parentOp) {
- return emitOpError() << "must be used within a region supporting "
- "cancellation point directive";
- }
+ Operation *thisOp = (*this).getOperation();
if ((cct == ClauseCancellationConstructType::Parallel) &&
- !(isa<ParallelOp>(parentOp))) {
+ !thisOp->getParentOfType<ParallelOp>()) {
return emitOpError() << "cancellation point parallel must appear "
<< "inside a parallel region";
}
if ((cct == ClauseCancellationConstructType::Loop) &&
- (!isa<LoopNestOp>(parentOp) || !isa<WsloopOp>(parentOp->getParentOp()))) {
+ !thisOp->getParentOfType<WsloopOp>()) {
return emitOpError() << "cancellation point loop must appear "
<< "inside a worksharing-loop region";
}
if ((cct == ClauseCancellationConstructType::Sections) &&
- !(isa<SectionsOp>(parentOp) || isa<SectionOp>(parentOp))) {
+ !thisOp->getParentOfType<SectionsOp>()) {
return emitOpError() << "cancellation point sections must appear "
<< "inside a sections region";
}
diff --git a/mlir/test/Dialect/OpenMP/ops.mlir b/mlir/test/Dialect/OpenMP/ops.mlir
index a5cf789402726..378a841ae62df 100644
--- a/mlir/test/Dialect/OpenMP/ops.mlir
+++ b/mlir/test/Dialect/OpenMP/ops.mlir
@@ -2201,6 +2201,48 @@ func.func @omp_cancel_sections() -> () {
return
}
+func.func @omp_cancel_parallel_nested(%if_cond : i1) -> () {
+ omp.parallel {
+ scf.if %if_cond {
+ // CHECK: omp.cancel cancellation_construct_type(parallel)
+ omp.cancel cancellation_construct_type(parallel)
+ }
+ // CHECK: omp.terminator
+ omp.terminator
+ }
+ return
+}
+
+func.func @omp_cancel_wsloop_nested(%lb : index, %ub : index, %step : index,
+ %if_cond : i1) {
+ omp.wsloop {
+ omp.loop_nest (%iv) : index = (%lb) to (%ub) step (%step) {
+ scf.if %if_cond {
+ // CHECK: omp.cancel cancellation_construct_type(loop)
+ omp.cancel cancellation_construct_type(loop)
+ }
+ // CHECK: omp.yield
+ omp.yield
+ }
+ }
+ return
+}
+
+func.func @omp_cancel_sections_nested(%if_cond : i1) -> () {
+ omp.sections {
+ omp.section {
+ scf.if %if_cond {
+ // CHECK: omp.cancel cancellation_construct_type(sections)
+ omp.cancel cancellation_construct_type(sections)
+ }
+ omp.terminator
+ }
+ // CHECK: omp.terminator
+ omp.terminator
+ }
+ return
+}
+
func.func @omp_cancellationpoint_parallel() -> () {
omp.parallel {
// CHECK: omp.cancellation_point cancellation_construct_type(parallel)
@@ -2241,6 +2283,46 @@ func.func @omp_cancellationpoint_sections() -> () {
return
}
+func.func @omp_cancellationpoint_parallel_nested(%if_cond : i1) -> () {
+ omp.parallel {
+ scf.if %if_cond {
+ // CHECK: omp.cancellation_point cancellation_construct_type(parallel)
+ omp.cancellation_point cancellation_construct_type(parallel)
+ }
+ omp.terminator
+ }
+ return
+}
+
+func.func @omp_cancellationpoint_wsloop_nested(%lb : index, %ub : index, %step : index, %if_cond : i1) {
+ omp.wsloop {
+ omp.loop_nest (%iv) : index = (%lb) to (%ub) step (%step) {
+ scf.if %if_cond {
+ // CHECK: omp.cancellation_point cancellation_construct_type(loop)
+ omp.cancellation_point cancellation_construct_type(loop)
+ }
+ // CHECK: omp.yield
+ omp.yield
+ }
+ }
+ return
+}
+
+func.func @omp_cancellationpoint_sections_nested(%if_cond : i1) -> () {
+ omp.sections {
+ omp.section {
+ scf.if %if_cond {
+ // CHECK: omp.cancellation_point cancellation_construct_type(sections)
+ omp.cancellation_point cancellation_construct_type(sections)
+ }
+ omp.terminator
+ }
+ // CHECK: omp.terminator
+ omp.terminator
+ }
+ return
+}
+
// CHECK-LABEL: @omp_taskgroup_no_tasks
func.func @omp_taskgroup_no_tasks() -> () {
|
|
@llvm/pr-subscribers-mlir Author: Tom Eccles (tblah) Changesomp.cancel and omp.cancellationpoint contain an attribute describing the type of parent construct which should be cancelled. e.g. Must be inside of a wsloop. Previously the verifer required the immediate parent to be this operation. This is not quite right because something like the following is valid: This patch relaxes the verifier to only require that some parent operation matches (not necessarily the immediate parent). Full diff: https://github.com/llvm/llvm-project/pull/134084.diff 2 Files Affected:
diff --git a/mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp b/mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp
index 882bc4071482f..e45d6d9fb3831 100644
--- a/mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp
+++ b/mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp
@@ -3103,22 +3103,15 @@ void CancelOp::build(OpBuilder &builder, OperationState &state,
LogicalResult CancelOp::verify() {
ClauseCancellationConstructType cct = getCancelDirective();
- Operation *parentOp = (*this)->getParentOp();
-
- if (!parentOp) {
- return emitOpError() << "must be used within a region supporting "
- "cancel directive";
- }
+ Operation *thisOp = (*this).getOperation();
if ((cct == ClauseCancellationConstructType::Parallel) &&
- !isa<ParallelOp>(parentOp)) {
+ !thisOp->getParentOfType<ParallelOp>()) {
return emitOpError() << "cancel parallel must appear "
<< "inside a parallel region";
}
if (cct == ClauseCancellationConstructType::Loop) {
- auto loopOp = dyn_cast<LoopNestOp>(parentOp);
- auto wsloopOp = llvm::dyn_cast_if_present<WsloopOp>(
- loopOp ? loopOp->getParentOp() : nullptr);
+ auto wsloopOp = thisOp->getParentOfType<WsloopOp>();
if (!wsloopOp) {
return emitOpError()
@@ -3134,12 +3127,12 @@ LogicalResult CancelOp::verify() {
}
} else if (cct == ClauseCancellationConstructType::Sections) {
- if (!(isa<SectionsOp>(parentOp) || isa<SectionOp>(parentOp))) {
+ auto sectionsOp = thisOp->getParentOfType<SectionsOp>();
+ if (!sectionsOp) {
return emitOpError() << "cancel sections must appear "
<< "inside a sections region";
}
- if (isa_and_nonnull<SectionsOp>(parentOp->getParentOp()) &&
- cast<SectionsOp>(parentOp->getParentOp()).getNowaitAttr()) {
+ if (sectionsOp.getNowait()) {
return emitError() << "A sections construct that is canceled "
<< "must not have a nowait clause";
}
@@ -3159,25 +3152,20 @@ void CancellationPointOp::build(OpBuilder &builder, OperationState &state,
LogicalResult CancellationPointOp::verify() {
ClauseCancellationConstructType cct = getCancelDirective();
- Operation *parentOp = (*this)->getParentOp();
-
- if (!parentOp) {
- return emitOpError() << "must be used within a region supporting "
- "cancellation point directive";
- }
+ Operation *thisOp = (*this).getOperation();
if ((cct == ClauseCancellationConstructType::Parallel) &&
- !(isa<ParallelOp>(parentOp))) {
+ !thisOp->getParentOfType<ParallelOp>()) {
return emitOpError() << "cancellation point parallel must appear "
<< "inside a parallel region";
}
if ((cct == ClauseCancellationConstructType::Loop) &&
- (!isa<LoopNestOp>(parentOp) || !isa<WsloopOp>(parentOp->getParentOp()))) {
+ !thisOp->getParentOfType<WsloopOp>()) {
return emitOpError() << "cancellation point loop must appear "
<< "inside a worksharing-loop region";
}
if ((cct == ClauseCancellationConstructType::Sections) &&
- !(isa<SectionsOp>(parentOp) || isa<SectionOp>(parentOp))) {
+ !thisOp->getParentOfType<SectionsOp>()) {
return emitOpError() << "cancellation point sections must appear "
<< "inside a sections region";
}
diff --git a/mlir/test/Dialect/OpenMP/ops.mlir b/mlir/test/Dialect/OpenMP/ops.mlir
index a5cf789402726..378a841ae62df 100644
--- a/mlir/test/Dialect/OpenMP/ops.mlir
+++ b/mlir/test/Dialect/OpenMP/ops.mlir
@@ -2201,6 +2201,48 @@ func.func @omp_cancel_sections() -> () {
return
}
+func.func @omp_cancel_parallel_nested(%if_cond : i1) -> () {
+ omp.parallel {
+ scf.if %if_cond {
+ // CHECK: omp.cancel cancellation_construct_type(parallel)
+ omp.cancel cancellation_construct_type(parallel)
+ }
+ // CHECK: omp.terminator
+ omp.terminator
+ }
+ return
+}
+
+func.func @omp_cancel_wsloop_nested(%lb : index, %ub : index, %step : index,
+ %if_cond : i1) {
+ omp.wsloop {
+ omp.loop_nest (%iv) : index = (%lb) to (%ub) step (%step) {
+ scf.if %if_cond {
+ // CHECK: omp.cancel cancellation_construct_type(loop)
+ omp.cancel cancellation_construct_type(loop)
+ }
+ // CHECK: omp.yield
+ omp.yield
+ }
+ }
+ return
+}
+
+func.func @omp_cancel_sections_nested(%if_cond : i1) -> () {
+ omp.sections {
+ omp.section {
+ scf.if %if_cond {
+ // CHECK: omp.cancel cancellation_construct_type(sections)
+ omp.cancel cancellation_construct_type(sections)
+ }
+ omp.terminator
+ }
+ // CHECK: omp.terminator
+ omp.terminator
+ }
+ return
+}
+
func.func @omp_cancellationpoint_parallel() -> () {
omp.parallel {
// CHECK: omp.cancellation_point cancellation_construct_type(parallel)
@@ -2241,6 +2283,46 @@ func.func @omp_cancellationpoint_sections() -> () {
return
}
+func.func @omp_cancellationpoint_parallel_nested(%if_cond : i1) -> () {
+ omp.parallel {
+ scf.if %if_cond {
+ // CHECK: omp.cancellation_point cancellation_construct_type(parallel)
+ omp.cancellation_point cancellation_construct_type(parallel)
+ }
+ omp.terminator
+ }
+ return
+}
+
+func.func @omp_cancellationpoint_wsloop_nested(%lb : index, %ub : index, %step : index, %if_cond : i1) {
+ omp.wsloop {
+ omp.loop_nest (%iv) : index = (%lb) to (%ub) step (%step) {
+ scf.if %if_cond {
+ // CHECK: omp.cancellation_point cancellation_construct_type(loop)
+ omp.cancellation_point cancellation_construct_type(loop)
+ }
+ // CHECK: omp.yield
+ omp.yield
+ }
+ }
+ return
+}
+
+func.func @omp_cancellationpoint_sections_nested(%if_cond : i1) -> () {
+ omp.sections {
+ omp.section {
+ scf.if %if_cond {
+ // CHECK: omp.cancellation_point cancellation_construct_type(sections)
+ omp.cancellation_point cancellation_construct_type(sections)
+ }
+ omp.terminator
+ }
+ // CHECK: omp.terminator
+ omp.terminator
+ }
+ return
+}
+
// CHECK-LABEL: @omp_taskgroup_no_tasks
func.func @omp_taskgroup_no_tasks() -> () {
|
|
Good catch.
Is the following allowed? |
My reading of the standard seems to allow this, but classic flang and gfortran both refuse to compile it, along with clang and gcc (after rewriting in c++). Clang, gfortran and gcc all describe the cancel construct as "orphaned". |
If it is specified to require a closely nested construct then the above code is invalid. It is also invalid to have other OpenMP constructs in between. Will the relaxation in check miss this? |
From OpenMP 6.0:
But being "closely nested" only refers to OpenMP constructs:
I find this a bit surprising because with this requirement, I don't see why the cancel-directive-name clause exists, let alone is compulsory. Anyway I will update this patch to remove all of the MLIR verification here, because I agree your example seems standards compliant. But for now I will keep the flang semantic checks (which correctly enforce close nesting but do not allow the cancel in a subroutine call) because no other compiler supports this either, and I think it is more useful to have a semantic check which can catch this at compile time than to allow code with an incorrect cancel-directive-name and have the cancel be completely ignored (which I believe is what the runtime would do). |
|
@kiranchandramohan are you happy with this with da8639e? |
@tblah I missed the point about why my example is standards compliant if the standard is talking about closely nested OpenMP constructs. Closely nested OpenMP constructs have to be statically nested. I thought augmenting the check to ensure that none of the intervening operations are OpenMP would be better. |
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) omp.cancel and omp.cancellationpoint contain an attribute describing the type of parent construct which should be cancelled. e.g. ``` !$omp cancel do ``` Must be inside of a wsloop. Previously the verifer required the immediate parent to be this operation. This is not quite right because something like the following is valid: ``` !$omp parallel do do i = 1, N if (cond) then !$omp cancel do endif enddo ``` This patch relaxes the verifier to only require that some parent operation matches (not necessarily the immediate parent).
omp.cancel and omp.cancellationpoint contain an attribute describing the type of parent construct which should be cancelled. e.g.
Must be inside of a wsloop. Previously the verifer required the immediate parent to be this operation. This is not quite right because something like the following is valid:
This patch relaxes the verifier to only require that some parent operation matches (not necessarily the immediate parent).