[flang-commits] [flang] [flang][acc] remap symbol appearing in reduction clause (PR #168876)
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flang-commits at lists.llvm.org
Tue Nov 25 01:25:44 PST 2025
https://github.com/jeanPerier updated https://github.com/llvm/llvm-project/pull/168876
>From 901d0cf65f8dbc09e795c72d96915c56547d424e Mon Sep 17 00:00:00 2001
From: Jean Perier <jperier at nvidia.com>
Date: Thu, 20 Nov 2025 06:02:40 -0800
Subject: [PATCH] [flang][acc] remap symbol appearing in reduction clause
---
flang/lib/Lower/OpenACC.cpp | 35 ++--
.../Lower/OpenACC/acc-reduction-remapping.f90 | 160 ++++++++++++++++++
2 files changed, 183 insertions(+), 12 deletions(-)
create mode 100644 flang/test/Lower/OpenACC/acc-reduction-remapping.f90
diff --git a/flang/lib/Lower/OpenACC.cpp b/flang/lib/Lower/OpenACC.cpp
index 98a3aced3f528..d10169e236471 100644
--- a/flang/lib/Lower/OpenACC.cpp
+++ b/flang/lib/Lower/OpenACC.cpp
@@ -1622,16 +1622,18 @@ static bool isSupportedReductionType(mlir::Type ty) {
return fir::isa_trivial(ty);
}
-static void
-genReductions(const Fortran::parser::AccObjectListWithReduction &objectList,
- Fortran::lower::AbstractConverter &converter,
- Fortran::semantics::SemanticsContext &semanticsContext,
- Fortran::lower::StatementContext &stmtCtx,
- llvm::SmallVectorImpl<mlir::Value> &reductionOperands,
- llvm::SmallVector<mlir::Attribute> &reductionRecipes,
- llvm::ArrayRef<mlir::Value> async,
- llvm::ArrayRef<mlir::Attribute> asyncDeviceTypes,
- llvm::ArrayRef<mlir::Attribute> asyncOnlyDeviceTypes) {
+static void genReductions(
+ const Fortran::parser::AccObjectListWithReduction &objectList,
+ Fortran::lower::AbstractConverter &converter,
+ Fortran::semantics::SemanticsContext &semanticsContext,
+ Fortran::lower::StatementContext &stmtCtx,
+ llvm::SmallVectorImpl<mlir::Value> &reductionOperands,
+ llvm::SmallVector<mlir::Attribute> &reductionRecipes,
+ llvm::ArrayRef<mlir::Value> async,
+ llvm::ArrayRef<mlir::Attribute> asyncDeviceTypes,
+ llvm::ArrayRef<mlir::Attribute> asyncOnlyDeviceTypes,
+ llvm::SmallVectorImpl<std::pair<mlir::Value, Fortran::semantics::SymbolRef>>
+ *symbolPairs = nullptr) {
fir::FirOpBuilder &builder = converter.getFirOpBuilder();
const auto &objects = std::get<Fortran::parser::AccObjectList>(objectList.t);
const auto &op = std::get<Fortran::parser::ReductionOperator>(objectList.t);
@@ -1644,6 +1646,8 @@ genReductions(const Fortran::parser::AccObjectListWithReduction &objectList,
Fortran::semantics::Symbol &symbol = getSymbolFromAccObject(accObject);
Fortran::semantics::MaybeExpr designator = Fortran::common::visit(
[&](auto &&s) { return ea.Analyze(s); }, accObject.u);
+ bool isWholeSymbol =
+ !designator || Fortran::evaluate::UnwrapWholeSymbolDataRef(*designator);
fir::factory::AddrAndBoundsInfo info =
Fortran::lower::gatherDataOperandAddrAndBounds<
mlir::acc::DataBoundsOp, mlir::acc::DataBoundsType>(
@@ -1680,6 +1684,11 @@ genReductions(const Fortran::parser::AccObjectListWithReduction &objectList,
reductionRecipes.push_back(mlir::SymbolRefAttr::get(
builder.getContext(), recipe.getSymName().str()));
reductionOperands.push_back(op.getAccVar());
+ // Track the symbol and its corresponding mlir::Value if requested so that
+ // accesses inside the compute/loop regions use the acc.reduction variable.
+ if (symbolPairs && isWholeSymbol)
+ symbolPairs->emplace_back(op.getAccVar(),
+ Fortran::semantics::SymbolRef(symbol));
}
}
@@ -2545,7 +2554,8 @@ static mlir::acc::LoopOp createLoopOp(
&clause.u)) {
genReductions(reductionClause->v, converter, semanticsContext, stmtCtx,
reductionOperands, reductionRecipes, /*async=*/{},
- /*asyncDeviceTypes=*/{}, /*asyncOnlyDeviceTypes=*/{});
+ /*asyncDeviceTypes=*/{}, /*asyncOnlyDeviceTypes=*/{},
+ &dataOperandSymbolPairs);
} else if (std::get_if<Fortran::parser::AccClause::Seq>(&clause.u)) {
for (auto crtDeviceTypeAttr : crtDeviceTypes)
seqDeviceTypes.push_back(crtDeviceTypeAttr);
@@ -2995,7 +3005,8 @@ static Op createComputeOp(
if (!combinedConstructs) {
genReductions(reductionClause->v, converter, semanticsContext, stmtCtx,
reductionOperands, reductionRecipes, async,
- asyncDeviceTypes, asyncOnlyDeviceTypes);
+ asyncDeviceTypes, asyncOnlyDeviceTypes,
+ &dataOperandSymbolPairs);
} else {
auto crtDataStart = dataClauseOperands.size();
genDataOperandOperations<mlir::acc::CopyinOp>(
diff --git a/flang/test/Lower/OpenACC/acc-reduction-remapping.f90 b/flang/test/Lower/OpenACC/acc-reduction-remapping.f90
new file mode 100644
index 0000000000000..6ee365f278678
--- /dev/null
+++ b/flang/test/Lower/OpenACC/acc-reduction-remapping.f90
@@ -0,0 +1,160 @@
+! Test remapping of variables appearing in OpenACC reduction clause
+! to the related acc dialect data operation result.
+
+! This tests checks how the hlfir.declare is recreated and used inside
+! the acc compute region.
+
+! RUN: bbc -fopenacc -emit-hlfir %s -o - | FileCheck %s
+
+subroutine scalar_combined(x, y)
+ real :: y, x(100)
+ !$acc parallel copyin(x) reduction(+:y)
+ do i=1,100
+ y = y + x(i)
+ end do
+ !$acc end parallel
+end subroutine
+
+subroutine scalar_split(x, y)
+ real :: y, x(100)
+ !$acc parallel copyin(x) copyout(y)
+ !$acc loop reduction(+:y)
+ do i=1,100
+ y = y + x(i)
+ end do
+ !$acc end parallel
+end subroutine
+
+subroutine array_combined(x, y, n)
+ integer(8) :: n
+ real :: y(n), x(100, n)
+ !$acc parallel copyin(x) reduction(+:y)
+ do j=1,n
+ do i=1,100
+ y(j) = y(j) + x(i, j)
+ end do
+ end do
+ !$acc end parallel
+end subroutine
+
+subroutine array_split(x, y, n)
+ integer(8) :: n
+ real :: y(n), x(100, n)
+ !$acc parallel copyin(x) copyout(y)
+ !$acc loop reduction(+:y)
+ do j=1,n
+ do i=1,100
+ y(j) = y(j) + x(i, j)
+ end do
+ end do
+ !$acc end parallel
+end subroutine
+
+! CHECK-LABEL: func.func @_QPscalar_combined(
+! CHECK: %[[DUMMY_SCOPE_0:.*]] = fir.dummy_scope : !fir.dscope
+! CHECK: %[[DECLARE_Y:.*]]:2 = hlfir.declare %{{.*}} dummy_scope %[[DUMMY_SCOPE_0]] arg 2 {uniq_name = "_QFscalar_combinedEy"} : (!fir.ref<f32>, !fir.dscope) -> (!fir.ref<f32>, !fir.ref<f32>)
+! CHECK: %[[REDUCTION_Y:.*]] = acc.reduction varPtr(%[[DECLARE_Y]]#0 : !fir.ref<f32>) -> !fir.ref<f32> {name = "y"}
+! CHECK: acc.parallel {{.*}} reduction(@reduction_add_ref_f32 -> %[[REDUCTION_Y]] : !fir.ref<f32>) {
+! CHECK: %[[DUMMY_SCOPE_1:.*]] = fir.dummy_scope : !fir.dscope
+! CHECK: %[[DECLARE_RED_PAR:.*]]:2 = hlfir.declare %[[REDUCTION_Y]] dummy_scope %[[DUMMY_SCOPE_1]] arg 2 {uniq_name = "_QFscalar_combinedEy"} : (!fir.ref<f32>, !fir.dscope) -> (!fir.ref<f32>, !fir.ref<f32>)
+! CHECK: %[[PRIVATE_I:.*]] = acc.private varPtr({{.*}}) -> !fir.ref<i32> {implicit = true, name = "i"}
+! CHECK: acc.loop private(@privatization_ref_i32 -> %[[PRIVATE_I]] : !fir.ref<i32>) {{.*}} {
+! CHECK: %[[DECLARE_I:.*]]:2 = hlfir.declare %[[PRIVATE_I]] {uniq_name = "_QFscalar_combinedEi"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
+! CHECK: fir.store %[[VAL_0:.*]] to %[[DECLARE_I]]#0 : !fir.ref<i32>
+! CHECK: %[[LOAD_RED:.*]] = fir.load %[[DECLARE_RED_PAR]]#0 : !fir.ref<f32>
+! CHECK: {{.*}} = hlfir.designate {{.*}} : (!fir.ref<!fir.array<100xf32>>, i64) -> !fir.ref<f32>
+! CHECK: {{.*}} = fir.load {{.*}} : !fir.ref<f32>
+! CHECK: %[[ADDF:.*]] = arith.addf %[[LOAD_RED]], {{.*}} {{.*}}: f32
+! CHECK: hlfir.assign %[[ADDF]] to %[[DECLARE_RED_PAR]]#0 : f32, !fir.ref<f32>
+! CHECK: acc.yield
+! CHECK: }
+! CHECK: acc.yield
+! CHECK: }
+! CHECK: return
+! CHECK: }
+!
+!
+! CHECK-LABEL: func.func @_QPscalar_split(
+! CHECK: %[[DUMMY_SCOPE_0:.*]] = fir.dummy_scope : !fir.dscope
+! CHECK: %[[DECLARE_Y:.*]]:2 = hlfir.declare %{{.*}} dummy_scope %[[DUMMY_SCOPE_0]] arg 2 {uniq_name = "_QFscalar_splitEy"} : (!fir.ref<f32>, !fir.dscope) -> (!fir.ref<f32>, !fir.ref<f32>)
+! CHECK: %[[CREATE_Y:.*]] = acc.create varPtr(%[[DECLARE_Y]]#0 : !fir.ref<f32>) -> !fir.ref<f32> {dataClause = #acc<data_clause acc_copyout>, name = "y"}
+! CHECK: acc.parallel dataOperands({{.*}}%[[CREATE_Y]] : {{.*}}) {
+! CHECK: %[[DUMMY_SCOPE_1:.*]] = fir.dummy_scope : !fir.dscope
+! CHECK: %[[DECLARE_Y_PAR:.*]]:2 = hlfir.declare %[[CREATE_Y]] dummy_scope %[[DUMMY_SCOPE_1]] arg 2 {uniq_name = "_QFscalar_splitEy"} : (!fir.ref<f32>, !fir.dscope) -> (!fir.ref<f32>, !fir.ref<f32>)
+! CHECK: %[[REDUCTION_Y:.*]] = acc.reduction varPtr(%[[DECLARE_Y_PAR]]#0 : !fir.ref<f32>) -> !fir.ref<f32> {name = "y"}
+! CHECK: %[[PRIVATE_I:.*]] = acc.private varPtr({{.*}}) -> !fir.ref<i32> {implicit = true, name = "i"}
+! CHECK: acc.loop private(@privatization_ref_i32 -> %[[PRIVATE_I]] : !fir.ref<i32>) reduction(@reduction_add_ref_f32 -> %[[REDUCTION_Y]] : !fir.ref<f32>) {{.*}} {
+! CHECK: %[[DUMMY_SCOPE_2:.*]] = fir.dummy_scope : !fir.dscope
+! CHECK: %[[DECLARE_RED:.*]]:2 = hlfir.declare %[[REDUCTION_Y]] dummy_scope %[[DUMMY_SCOPE_2]] arg 2 {uniq_name = "_QFscalar_splitEy"} : (!fir.ref<f32>, !fir.dscope) -> (!fir.ref<f32>, !fir.ref<f32>)
+! CHECK: %[[LOAD_RED:.*]] = fir.load %[[DECLARE_RED]]#0 : !fir.ref<f32>
+! CHECK: %[[ADDF:.*]] = arith.addf %[[LOAD_RED]], {{.*}} {{.*}}: f32
+! CHECK: hlfir.assign %[[ADDF]] to %[[DECLARE_RED]]#0 : f32, !fir.ref<f32>
+! CHECK: acc.yield
+! CHECK: }
+! CHECK: acc.yield
+! CHECK: }
+! CHECK: return
+! CHECK: }
+
+
+! CHECK-LABEL: func.func @_QParray_combined(
+! CHECK: %[[DUMMY_SCOPE_0:.*]] = fir.dummy_scope : !fir.dscope
+! CHECK: %[[DECLARE_N:.*]]:2 = hlfir.declare %{{.*}} dummy_scope %[[DUMMY_SCOPE_0]] arg 3 {uniq_name = "_QFarray_combinedEn"} : (!fir.ref<i64>, !fir.dscope) -> (!fir.ref<i64>, !fir.ref<i64>)
+! CHECK: %[[DECLARE_Y:.*]]:2 = hlfir.declare %{{.*}}({{.*}}) dummy_scope %[[DUMMY_SCOPE_0]] arg 2 {uniq_name = "_QFarray_combinedEy"} : (!fir.ref<!fir.array<?xf32>>, {{.*}}, !fir.dscope) -> (!fir.box<!fir.array<?xf32>>, !fir.ref<!fir.array<?xf32>>)
+! CHECK: %[[REDUCTION_Y:.*]] = acc.reduction var(%[[DECLARE_Y]]#0 : !fir.box<!fir.array<?xf32>>) -> !fir.box<!fir.array<?xf32>> {name = "y"}
+! CHECK: acc.parallel dataOperands({{.*}}) reduction(@reduction_add_box_Uxf32 -> %[[REDUCTION_Y]] : !fir.box<!fir.array<?xf32>>) {
+! CHECK: %[[DUMMY_SCOPE_1:.*]] = fir.dummy_scope : !fir.dscope
+! CHECK: %[[BOX_ADDR_RED:.*]] = fir.box_addr %[[REDUCTION_Y]] : (!fir.box<!fir.array<?xf32>>) -> !fir.ref<!fir.array<?xf32>>
+! CHECK: %[[DECLARE_Y_PAR:.*]]:2 = hlfir.declare %[[BOX_ADDR_RED]]({{.*}}) dummy_scope %[[DUMMY_SCOPE_1]] arg 2 {uniq_name = "_QFarray_combinedEy"} : (!fir.ref<!fir.array<?xf32>>, {{.*}}, !fir.dscope) -> (!fir.box<!fir.array<?xf32>>, !fir.ref<!fir.array<?xf32>>)
+! CHECK: %[[PRIVATE_J:.*]] = acc.private varPtr({{.*}}) -> !fir.ref<i32> {implicit = true, name = "j"}
+! CHECK: acc.loop private(@privatization_ref_i32 -> %[[PRIVATE_J]] : !fir.ref<i32>) {{.*}} {
+! CHECK: %[[PRIVATE_I:.*]] = acc.private varPtr({{.*}}) -> !fir.ref<i32> {implicit = true, name = "i"}
+! CHECK: acc.loop private(@privatization_ref_i32 -> %[[PRIVATE_I]] : !fir.ref<i32>) {{.*}} {
+! CHECK: %[[DESIGNATE_RED:.*]] = hlfir.designate %[[DECLARE_Y_PAR]]#0 ({{.*}}) : (!fir.box<!fir.array<?xf32>>, i64) -> !fir.ref<f32>
+! CHECK: %[[LOAD_OLD:.*]] = fir.load %[[DESIGNATE_RED]] : !fir.ref<f32>
+! CHECK: {{.*}} = hlfir.designate {{.*}} : (!fir.box<!fir.array<100x?xf32>>, i64, i64) -> !fir.ref<f32>
+! CHECK: {{.*}} = fir.load {{.*}} : !fir.ref<f32>
+! CHECK: %[[ADDF:.*]] = arith.addf %[[LOAD_OLD]], {{.*}} {{.*}}: f32
+! CHECK: %[[DESIGNATE_RED2:.*]] = hlfir.designate %[[DECLARE_Y_PAR]]#0 ({{.*}}) : (!fir.box<!fir.array<?xf32>>, i64) -> !fir.ref<f32>
+! CHECK: hlfir.assign %[[ADDF]] to %[[DESIGNATE_RED2]] : f32, !fir.ref<f32>
+! CHECK: acc.yield
+! CHECK: }
+! CHECK: acc.yield
+! CHECK: }
+! CHECK: acc.yield
+! CHECK: }
+! CHECK: return
+! CHECK: }
+
+
+! CHECK-LABEL: func.func @_QParray_split(
+! CHECK: %[[DUMMY_SCOPE_0:.*]] = fir.dummy_scope : !fir.dscope
+! CHECK: %[[DECLARE_Y:.*]]:2 = hlfir.declare %{{.*}}({{.*}}) dummy_scope %[[DUMMY_SCOPE_0]] arg 2 {uniq_name = "_QFarray_splitEy"} : (!fir.ref<!fir.array<?xf32>>, {{.*}}, !fir.dscope) -> (!fir.box<!fir.array<?xf32>>, !fir.ref<!fir.array<?xf32>>)
+! CHECK: %[[CREATE_Y:.*]] = acc.create var(%[[DECLARE_Y]]#0 : !fir.box<!fir.array<?xf32>>) -> !fir.box<!fir.array<?xf32>> {dataClause = #acc<data_clause acc_copyout>, name = "y"}
+! CHECK: acc.parallel dataOperands({{.*}}%[[CREATE_Y]] : {{.*}}) {
+! CHECK: %[[DUMMY_SCOPE_1:.*]] = fir.dummy_scope : !fir.dscope
+! CHECK: %[[BOX_ADDR_Y:.*]] = fir.box_addr %[[CREATE_Y]] : (!fir.box<!fir.array<?xf32>>) -> !fir.ref<!fir.array<?xf32>>
+! CHECK: %[[DECLARE_Y_PAR:.*]]:2 = hlfir.declare %[[BOX_ADDR_Y]]({{.*}}) dummy_scope %[[DUMMY_SCOPE_1]] arg 2 {uniq_name = "_QFarray_splitEy"} : (!fir.ref<!fir.array<?xf32>>, {{.*}}, !fir.dscope) -> (!fir.box<!fir.array<?xf32>>, !fir.ref<!fir.array<?xf32>>)
+! CHECK: %[[REDUCTION_Y:.*]] = acc.reduction var(%[[DECLARE_Y_PAR]]#0 : !fir.box<!fir.array<?xf32>>) -> !fir.box<!fir.array<?xf32>> {name = "y"}
+! CHECK: %[[PRIVATE_J:.*]] = acc.private varPtr({{.*}}) -> !fir.ref<i32> {implicit = true, name = "j"}
+! CHECK: acc.loop private(@privatization_ref_i32 -> %[[PRIVATE_J]] : !fir.ref<i32>) reduction(@reduction_add_box_Uxf32 -> %[[REDUCTION_Y]] : !fir.box<!fir.array<?xf32>>) {{.*}} {
+! CHECK: %[[BOX_ADDR_RED:.*]] = fir.box_addr %[[REDUCTION_Y]] : (!fir.box<!fir.array<?xf32>>) -> !fir.ref<!fir.array<?xf32>>
+! CHECK: %[[DUMMY_SCOPE_2:.*]] = fir.dummy_scope : !fir.dscope
+! CHECK: %[[DECLARE_Y_LOOP_PAR:.*]]:2 = hlfir.declare %[[BOX_ADDR_RED]]({{.*}}) dummy_scope %[[DUMMY_SCOPE_2]] arg 2 {uniq_name = "_QFarray_splitEy"} : (!fir.ref<!fir.array<?xf32>>, {{.*}}, !fir.dscope) -> (!fir.box<!fir.array<?xf32>>, !fir.ref<!fir.array<?xf32>>)
+! CHECK: %[[PRIVATE_I:.*]] = acc.private varPtr({{.*}}) -> !fir.ref<i32> {implicit = true, name = "i"}
+! CHECK: acc.loop private(@privatization_ref_i32 -> %[[PRIVATE_I]] : !fir.ref<i32>) {{.*}} {
+! CHECK: %[[DESIGNATE_RED:.*]] = hlfir.designate %[[DECLARE_Y_LOOP_PAR]]#0 ({{.*}}) : (!fir.box<!fir.array<?xf32>>, i64) -> !fir.ref<f32>
+! CHECK: %[[LOAD_OLD:.*]] = fir.load %[[DESIGNATE_RED]] : !fir.ref<f32>
+! CHECK: {{.*}} = hlfir.designate {{.*}} : (!fir.box<!fir.array<100x?xf32>>, i64, i64) -> !fir.ref<f32>
+! CHECK: {{.*}} = fir.load {{.*}} : !fir.ref<f32>
+! CHECK: %[[ADDF:.*]] = arith.addf %[[LOAD_OLD]], {{.*}} {{.*}}: f32
+! CHECK: %[[DESIGNATE_RED2:.*]] = hlfir.designate %[[DECLARE_Y_LOOP_PAR]]#0 ({{.*}}) : (!fir.box<!fir.array<?xf32>>, i64) -> !fir.ref<f32>
+! CHECK: hlfir.assign %[[ADDF]] to %[[DESIGNATE_RED2]] : f32, !fir.ref<f32>
+! CHECK: acc.yield
+! CHECK: }
+! CHECK: acc.yield
+! CHECK: }
+! CHECK: acc.yield
+! CHECK: }
+! CHECK: return
+! CHECK: }
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