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[MLIR][OpenMP] Add OpenMPToLLVMIRTranslation support for is_device_ptr #169367

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[MLIR][OpenMP] Add OpenMPToLLVMIRTranslation support for is_device_ptr #169367

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9 changes: 9 additions & 0 deletions flang/test/Integration/OpenMP/map-types-and-sizes.f90
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,15 @@ subroutine mapType_array
!$omp end target
end subroutine mapType_array

!CHECK: @.offload_sizes{{.*}} = private unnamed_addr constant [1 x i64] [i64 8]
!CHECK: @.offload_maptypes{{.*}} = private unnamed_addr constant [1 x i64] [i64 288]
subroutine mapType_is_device_ptr
use iso_c_binding, only : c_ptr
type(c_ptr) :: p
!$omp target is_device_ptr(p)
!$omp end target
end subroutine mapType_is_device_ptr

!CHECK: @.offload_sizes{{.*}} = private unnamed_addr constant [4 x i64] [i64 0, i64 24, i64 8, i64 0]
!CHECK: @.offload_maptypes{{.*}} = private unnamed_addr constant [4 x i64] [i64 32, i64 281474976711169, i64 281474976711171, i64 281474976711187]
subroutine mapType_ptr
Expand Down
16 changes: 10 additions & 6 deletions mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp
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Expand Up @@ -332,10 +332,6 @@ static LogicalResult checkImplementationStatus(Operation &op) {
op.getInReductionSyms())
result = todo("in_reduction");
};
auto checkIsDevicePtr = [&todo](auto op, LogicalResult &result) {
if (!op.getIsDevicePtrVars().empty())
result = todo("is_device_ptr");
};
auto checkLinear = [&todo](auto op, LogicalResult &result) {
if (!op.getLinearVars().empty() || !op.getLinearStepVars().empty())
result = todo("linear");
Expand Down Expand Up @@ -444,7 +440,6 @@ static LogicalResult checkImplementationStatus(Operation &op) {
checkBare(op, result);
checkDevice(op, result);
checkInReduction(op, result);
checkIsDevicePtr(op, result);
})
.Default([](Operation &) {
// Assume all clauses for an operation can be translated unless they are
Expand Down Expand Up @@ -3875,6 +3870,11 @@ convertClauseMapFlags(omp::ClauseMapFlags mlirFlags) {
if (mapTypeToBool(omp::ClauseMapFlags::attach))
mapType |= llvm::omp::OpenMPOffloadMappingFlags::OMP_MAP_ATTACH;

if (mapTypeToBool(omp::ClauseMapFlags::is_device_ptr)) {
mapType |= llvm::omp::OpenMPOffloadMappingFlags::OMP_MAP_TARGET_PARAM;
mapType |= llvm::omp::OpenMPOffloadMappingFlags::OMP_MAP_LITERAL;
}

return mapType;
}

Expand Down Expand Up @@ -3996,6 +3996,9 @@ static void collectMapDataFromMapOperands(
llvm::Value *origValue = moduleTranslation.lookupValue(offloadPtr);
auto mapType = convertClauseMapFlags(mapOp.getMapType());
auto mapTypeAlways = llvm::omp::OpenMPOffloadMappingFlags::OMP_MAP_ALWAYS;
bool isDevicePtr =
(mapOp.getMapType() & omp::ClauseMapFlags::is_device_ptr) !=
omp::ClauseMapFlags::none;

mapData.OriginalValue.push_back(origValue);
mapData.BasePointers.push_back(origValue);
Expand Down Expand Up @@ -4029,7 +4032,8 @@ static void collectMapDataFromMapOperands(
mapData.Names.push_back(LLVM::createMappingInformation(
mapOp.getLoc(), *moduleTranslation.getOpenMPBuilder()));
mapData.DevicePointers.push_back(
llvm::OpenMPIRBuilder::DeviceInfoTy::Address);
isDevicePtr ? llvm::OpenMPIRBuilder::DeviceInfoTy::Pointer
: llvm::OpenMPIRBuilder::DeviceInfoTy::Address);
mapData.IsAMapping.push_back(false);
mapData.IsAMember.push_back(checkIsAMember(hasDevAddrOperands, mapOp));
}
Expand Down
17 changes: 17 additions & 0 deletions mlir/test/Target/LLVMIR/omptarget-llvm.mlir
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Expand Up @@ -622,3 +622,20 @@ module attributes {omp.target_triples = ["amdgcn-amd-amdhsa"]} {
// CHECK: br label %[[VAL_40]]
// CHECK: omp.done: ; preds = %[[VAL_68]], %[[VAL_63]], %[[VAL_32]]
// CHECK: ret void

// -----

module attributes {omp.target_triples = ["amdgcn-amd-amdhsa"]} {
llvm.func @_QPomp_target_is_device_ptr(%arg0 : !llvm.ptr) {
%map = omp.map.info var_ptr(%arg0 : !llvm.ptr, !llvm.ptr)
map_clauses(is_device_ptr) capture(ByRef) -> !llvm.ptr {name = ""}
omp.target map_entries(%map -> %ptr_arg : !llvm.ptr) {
omp.terminator
}
llvm.return
}
}

// CHECK: @.offload_sizes = private unnamed_addr constant [1 x i64] [i64 8]
// CHECK: @.offload_maptypes = private unnamed_addr constant [1 x i64] [i64 288]
// CHECK-LABEL: define void @_QPomp_target_is_device_ptr
11 changes: 0 additions & 11 deletions mlir/test/Target/LLVMIR/openmp-todo.mlir
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Expand Up @@ -238,17 +238,6 @@ llvm.func @target_in_reduction(%x : !llvm.ptr) {

// -----

llvm.func @target_is_device_ptr(%x : !llvm.ptr) {
// expected-error@below {{not yet implemented: Unhandled clause is_device_ptr in omp.target operation}}
// expected-error@below {{LLVM Translation failed for operation: omp.target}}
omp.target is_device_ptr(%x : !llvm.ptr) {
omp.terminator
}
llvm.return
}

// -----

llvm.func @target_enter_data_depend(%x: !llvm.ptr) {
// expected-error@below {{not yet implemented: Unhandled clause depend in omp.target_enter_data operation}}
// expected-error@below {{LLVM Translation failed for operation: omp.target_enter_data}}
Expand Down
46 changes: 46 additions & 0 deletions offload/test/offloading/fortran/target-is-device-ptr.f90
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@@ -0,0 +1,46 @@
! Validate that a device pointer obtained via omp_get_mapped_ptr can be used
! inside a TARGET region with the is_device_ptr clause.
! REQUIRES: flang, amdgcn-amd-amdhsa

! RUN: %libomptarget-compile-fortran-run-and-check-generic

program is_device_ptr_target
use iso_c_binding, only : c_ptr, c_loc
implicit none

interface
function omp_get_mapped_ptr(host_ptr, device_num) &
bind(C, name="omp_get_mapped_ptr")
use iso_c_binding, only : c_ptr, c_int
type(c_ptr) :: omp_get_mapped_ptr
type(c_ptr), value :: host_ptr
integer(c_int), value :: device_num
end function omp_get_mapped_ptr
end interface

integer, parameter :: n = 4
integer, parameter :: dev = 0
integer, target :: a(n)
type(c_ptr) :: dptr
integer :: flag

a = [2, 4, 6, 8]
flag = 0

!$omp target data map(tofrom: a, flag)
dptr = omp_get_mapped_ptr(c_loc(a), dev)

!$omp target is_device_ptr(dptr) map(tofrom: flag)
flag = flag + 1
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@abhinavgaba abhinavgaba Nov 26, 2025

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dptr is still not used inside the target construct. Is your goal to validate that dptr is correctly passed into the target, or just that this doesn't cause a segfault/offload-failure?

If it's the former, then one way to do it is by calling c_f_pointer inside the target region, and reading/writing the pointee via the fortran pointer. Another way is to transfer dptr into an INTEGER(C_INTPTR_T) both inside and outside the target region, print it, and CHECK that the two addresses printed are identical.

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@TIFitis TIFitis Nov 27, 2025

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I tried adding the call to c_f_pointer inside the target region in the previous test. But it causes a runtime failure, and I'm not sure if the failure is directly related to the is_device_ptr implementation or some other mapping bug.

If you're happy with the current simpler test for this PR, then I can work on debugging a fix for that failure when I return from vacation in the new year. Otherwise, I'll put this PR on hold until I can come up with a working version of that test with a call to c_f_pointer inside the target region.

Let me know which you prefer, thanks.

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@ergawy ergawy Nov 28, 2025

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I think it makes sense to tighten the test before merging. I might be missing something but I tried the following experiment:

 ! RUN: %libomptarget-compile-fortran-run-and-check-generic
 
 program is_device_ptr_target
-  use iso_c_binding, only : c_ptr, c_loc
+  use iso_c_binding, only : c_ptr, c_loc, c_intptr_t, C_NULL_PTR
   implicit none
 
   interface
@@ -22,19 +22,25 @@ program is_device_ptr_target
   integer, parameter :: dev = 0
   integer, target :: a(n)
   type(c_ptr) :: dptr
+  type(c_ptr) :: dptr_cpy
   integer :: flag
 
   a = [2, 4, 6, 8]
   flag = 0
+  dptr_cpy = C_NULL_PTR
 
   !$omp target data map(tofrom: a, flag)
     dptr = omp_get_mapped_ptr(c_loc(a), dev)
+    write(*, '(Z16)') dptr
+    write(*, '(Z16)') dptr_cpy
 
-    !$omp target is_device_ptr(dptr) map(tofrom: flag)
+    !$omp target is_device_ptr(dptr) map(tofrom: flag, dptr_cpy)
       flag = flag + 1
+      dptr_cpy = dptr
     !$omp end target
   !$omp end target data
 
+  write(*, '(Z16)') dptr_cpy
   if (flag .eq. 1 .and. all(a == [2, 4, 6, 8])) then
     print *, "PASS"
   else

And this prints:

    7C35B9220000
               0
               0
 PASS

which might mean that the device pointer kernel argument is not properly passed to the kernel. Let me know if I misinterpreted this.

!$omp end target
!$omp end target data

if (flag .eq. 1 .and. all(a == [2, 4, 6, 8])) then
print *, "PASS"
else
print *, "FAIL", a
end if

end program is_device_ptr_target

!CHECK: PASS