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[flang][cuda] Improve data transfer detection by filtering symbols #98378

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Jul 11, 2024
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[flang][cuda] Improve data transfer detection by filtering symbols #98378

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1e86b12
[flang][cuda] Improve data trsanfer detection by filtering symbols
clementval Jul 8, 2024
5a739e8
Update flang/test/Lower/CUDA/cuda-data-transfer.cuf
clementval Jul 10, 2024
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14 changes: 12 additions & 2 deletions flang/include/flang/Evaluate/tools.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1073,6 +1073,16 @@ extern template semantics::UnorderedSymbolSet CollectSymbols(
extern template semantics::UnorderedSymbolSet CollectSymbols(
const Expr<SubscriptInteger> &);

// Collects Symbols of interest for the CUDA data transfer in an expression
template <typename A>
semantics::UnorderedSymbolSet CollectCudaSymbols(const A &);
extern template semantics::UnorderedSymbolSet CollectCudaSymbols(
const Expr<SomeType> &);
extern template semantics::UnorderedSymbolSet CollectCudaSymbols(
const Expr<SomeInteger> &);
extern template semantics::UnorderedSymbolSet CollectCudaSymbols(
const Expr<SubscriptInteger> &);

// Predicate: does a variable contain a vector-valued subscript (not a triplet)?
bool HasVectorSubscript(const Expr<SomeType> &);

Expand Down Expand Up @@ -1236,7 +1246,7 @@ bool CheckForCoindexedObject(parser::ContextualMessages &,
// Get the number of distinct symbols with CUDA attribute in the expression.
template <typename A> inline int GetNbOfCUDADeviceSymbols(const A &expr) {
semantics::UnorderedSymbolSet symbols;
for (const Symbol &sym : CollectSymbols(expr)) {
for (const Symbol &sym : CollectCudaSymbols(expr)) {
if (const auto *details =
sym.GetUltimate().detailsIf<semantics::ObjectEntityDetails>()) {
if (details->cudaDataAttr() &&
Expand All @@ -1259,7 +1269,7 @@ template <typename A> inline bool HasCUDADeviceAttrs(const A &expr) {
inline bool HasCUDAImplicitTransfer(const Expr<SomeType> &expr) {
unsigned hostSymbols{0};
unsigned deviceSymbols{0};
for (const Symbol &sym : CollectSymbols(expr)) {
for (const Symbol &sym : CollectCudaSymbols(expr)) {
if (const auto *details =
sym.GetUltimate().detailsIf<semantics::ObjectEntityDetails>()) {
if (details->cudaDataAttr() &&
Expand Down
29 changes: 29 additions & 0 deletions flang/lib/Evaluate/tools.cpp
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Expand Up @@ -1000,6 +1000,35 @@ template semantics::UnorderedSymbolSet CollectSymbols(
template semantics::UnorderedSymbolSet CollectSymbols(
const Expr<SubscriptInteger> &);

struct CollectCudaSymbolsHelper : public SetTraverse<CollectCudaSymbolsHelper,
semantics::UnorderedSymbolSet> {
using Base =
SetTraverse<CollectCudaSymbolsHelper, semantics::UnorderedSymbolSet>;
CollectCudaSymbolsHelper() : Base{*this} {}
using Base::operator();
semantics::UnorderedSymbolSet operator()(const Symbol &symbol) const {
return {symbol};
}
// Overload some of the operator() to filter out the symbols that are not
// of interest for CUDA data transfer logic.
semantics::UnorderedSymbolSet operator()(const Subscript &) const {
return {};
}
semantics::UnorderedSymbolSet operator()(const ProcedureRef &) const {
return {};
}
};
template <typename A>
semantics::UnorderedSymbolSet CollectCudaSymbols(const A &x) {
return CollectCudaSymbolsHelper{}(x);
}
template semantics::UnorderedSymbolSet CollectCudaSymbols(
const Expr<SomeType> &);
template semantics::UnorderedSymbolSet CollectCudaSymbols(
const Expr<SomeInteger> &);
template semantics::UnorderedSymbolSet CollectCudaSymbols(
const Expr<SubscriptInteger> &);

// HasVectorSubscript()
struct HasVectorSubscriptHelper
: public AnyTraverse<HasVectorSubscriptHelper, bool,
Expand Down
34 changes: 32 additions & 2 deletions flang/test/Lower/CUDA/cuda-data-transfer.cuf
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Expand Up @@ -6,6 +6,12 @@ module mod1
type :: t1
integer :: i
end type

contains
function dev1(a)
integer, device :: a(:)
integer :: dev1
end function
end

subroutine sub1()
Expand Down Expand Up @@ -213,11 +219,35 @@ subroutine sub10(a, b)
res = a + b
end subroutine



! CHECK-LABEL: func.func @_QPsub10(
! CHECK-SAME: %[[ARG0:.*]]: !fir.ref<i32> {cuf.data_attr = #cuf.cuda<device>, fir.bindc_name = "a"}

! CHECK: %[[A:.*]]:2 = hlfir.declare %[[ARG0]] dummy_scope %1 {data_attr = #cuf.cuda<device>, uniq_name = "_QFsub10Ea"} : (!fir.ref<i32>, !fir.dscope) -> (!fir.ref<i32>, !fir.ref<i32>)
! CHECK: cuf.data_transfer %[[A]]#1 to %{{.*}}#0 {transfer_kind = #cuf.cuda_transfer<device_host>} : !fir.ref<i32>, !fir.ref<i32>
! CHECK-NOT: cuf.data_transfer

subroutine sub11(n)
integer :: n
real, dimension(10) :: h
real, dimension(n), device :: d
do i=1,10
h(i) = d(i)
end do
end subroutine

! CHECK-LABEL: func.func @_QPsub11
! CHECK: %[[RHS:.*]] = hlfir.designate %{{.*}} (%{{.*}}) : (!fir.box<!fir.array<?xf32>>, i64) -> !fir.ref<f32>
! CHECK: %[[LHS:.*]] = hlfir.designate %{{.*}} (%{{.*}}) : (!fir.ref<!fir.array<10xf32>>, i64) -> !fir.ref<f32>
! CHECK: cuf.data_transfer %[[RHS]] to %[[LHS]] {transfer_kind = #cuf.cuda_transfer<device_host>} : !fir.ref<f32>, !fir.ref<f32>

subroutine sub12()
use mod1
integer, device :: a(10)
integer :: x
x = dev1(a)
end subroutine

! CHECK-LABEL: func.func @_QPsub12
! CHECK: %{{.*}} = fir.call @_QMmod1Pdev1
! CHECK: hlfir.assign
! CHECK-NOT: cuf.data_transfer
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