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[flang][cuda] Update cuda data transfer rules for full managed assigment #175243

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clementval merged 2 commits into from
Jan 9, 2026
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[flang][cuda] Update cuda data transfer rules for full managed assigment #175243

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[flang][cuda] Update cuda data transfer rules for full managed assign…
clementval Jan 9, 2026
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3 changes: 1 addition & 2 deletions flang/include/flang/Evaluate/tools.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1352,8 +1352,7 @@ inline bool IsCUDADataTransfer(const A &lhs, const B &rhs) {
// Special cases performed on the host:
// - Only managed or unifed symbols are involved on RHS and LHS.
// - LHS is managed or unified and the RHS is host only.
if ((lhsNbManagedSymbols >= 1 && rhsNbManagedSymbols == 1 &&
rhsNbSymbols == 1) ||
if ((lhsNbManagedSymbols >= 1 && rhsNbManagedSymbols == rhsNbSymbols) ||
(lhsNbManagedSymbols >= 1 && rhsNbSymbols == 0)) {
return false;
}
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16 changes: 16 additions & 0 deletions flang/test/Lower/CUDA/cuda-data-transfer.cuf
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Expand Up @@ -588,3 +588,19 @@ end subroutine
! CHECK: %{{.*}} = cuf.alloc !fir.type<_QMmod1Tt3{spheres:!fir.box<!fir.heap<!fir.array<?x!fir.type<_QMmod1Ts{c:!fir.array<3xf32>}>>>>}> {bindc_name = "t", data_attr = #cuf.cuda<managed>, uniq_name = "_QFsub30Et"} -> !fir.ref<!fir.type<_QMmod1Tt3{spheres:!fir.box<!fir.heap<!fir.array<?x!fir.type<_QMmod1Ts{c:!fir.array<3xf32>}>>>>}>>
! CHECK: hlfir.assign
! CHECK-NOT: cuf.data_transfer

! Test that assigment with only managed variables on both rhs and lhs is done
! on the host.

subroutine sub31()
type :: t30
real, managed, allocatable :: q(:)
end type
type(t30), managed, allocatable :: x(:)
x(4)%q = x(3)%q
end subroutine

! CHECK-LABEL: func.func @_QPsub31()
! CHECK: cuf.alloc !fir.box<!fir.heap<!fir.array<?x!fir.type<_QFsub31Tt30{q:!fir.box<!fir.heap<!fir.array<?xf32>>>}>>>>
! CHECK: hlfir.assign
! CHECK-NOT: cuf.data_transfer