[Mlir-commits] [flang] [mlir] [flang][OpenMP] Allocate `reduction` init temps on the stack for GPUs (PR #146667)
Kareem Ergawy
llvmlistbot at llvm.org
Wed Jul 2 21:29:43 PDT 2025
https://github.com/ergawy updated https://github.com/llvm/llvm-project/pull/146667
>From 9a48bff311756ff1c3703f33d6acaecee195fe1e Mon Sep 17 00:00:00 2001
From: ergawy <kareem.ergawy at amd.com>
Date: Wed, 2 Jul 2025 05:31:38 -0500
Subject: [PATCH 1/2] [flang][OpenMP] Allocate `reduction` init temps on the
stack for GPUs
Temps needed for the reduction init regions are now allocate on the heap
all the time. However, this is performance killer for GPUs since malloc
calls are prohibitively expensive. Therefore, we should do these
allocations on the stack for GPU reductions.
---
.../Lower/Support/PrivateReductionUtils.cpp | 47 +++--
.../Lower/OpenMP/parallel-reduction-array.f90 | 166 ++++++++++--------
2 files changed, 119 insertions(+), 94 deletions(-)
diff --git a/flang/lib/Lower/Support/PrivateReductionUtils.cpp b/flang/lib/Lower/Support/PrivateReductionUtils.cpp
index e878041d37c03..c3a5b6101ce00 100644
--- a/flang/lib/Lower/Support/PrivateReductionUtils.cpp
+++ b/flang/lib/Lower/Support/PrivateReductionUtils.cpp
@@ -502,22 +502,37 @@ void PopulateInitAndCleanupRegionsHelper::initAndCleanupBoxedArray(
// Allocating on the heap in case the whole reduction/privatization is nested
// inside of a loop
- auto [temp, needsDealloc] = createTempFromMold(loc, builder, source);
- // if needsDealloc isn't statically false, add cleanup region. Always
- // do this for allocatable boxes because they might have been re-allocated
- // in the body of the loop/parallel region
-
- std::optional<int64_t> cstNeedsDealloc = fir::getIntIfConstant(needsDealloc);
- assert(cstNeedsDealloc.has_value() &&
- "createTempFromMold decides this statically");
- if (cstNeedsDealloc.has_value() && *cstNeedsDealloc != false) {
- mlir::OpBuilder::InsertionGuard guard(builder);
- createCleanupRegion(converter, loc, argType, cleanupRegion, sym,
- isDoConcurrent);
- } else {
- assert(!isAllocatableOrPointer &&
- "Pointer-like arrays must be heap allocated");
- }
+ auto temp = [&]() {
+ bool shouldAllocateOnStack = false;
+
+ // On the GPU, always allocate on the stack since heap allocatins are very
+ // expensive.
+ if (auto offloadMod = llvm::dyn_cast<mlir::omp::OffloadModuleInterface>(
+ *builder.getModule()))
+ shouldAllocateOnStack = offloadMod.getIsGPU();
+
+ if (shouldAllocateOnStack)
+ return createStackTempFromMold(loc, builder, source);
+
+ auto [temp, needsDealloc] = createTempFromMold(loc, builder, source);
+ // if needsDealloc isn't statically false, add cleanup region. Always
+ // do this for allocatable boxes because they might have been re-allocated
+ // in the body of the loop/parallel region
+
+ std::optional<int64_t> cstNeedsDealloc =
+ fir::getIntIfConstant(needsDealloc);
+ assert(cstNeedsDealloc.has_value() &&
+ "createTempFromMold decides this statically");
+ if (cstNeedsDealloc.has_value() && *cstNeedsDealloc != false) {
+ mlir::OpBuilder::InsertionGuard guard(builder);
+ createCleanupRegion(converter, loc, argType, cleanupRegion, sym,
+ isDoConcurrent);
+ } else {
+ assert(!isAllocatableOrPointer &&
+ "Pointer-like arrays must be heap allocated");
+ }
+ return temp;
+ }();
// Put the temporary inside of a box:
// hlfir::genVariableBox doesn't handle non-default lower bounds
diff --git a/flang/test/Lower/OpenMP/parallel-reduction-array.f90 b/flang/test/Lower/OpenMP/parallel-reduction-array.f90
index 8e3de498f59c1..4f889d9a4e77f 100644
--- a/flang/test/Lower/OpenMP/parallel-reduction-array.f90
+++ b/flang/test/Lower/OpenMP/parallel-reduction-array.f90
@@ -1,5 +1,8 @@
-! RUN: bbc -emit-hlfir -fopenmp -o - %s 2>&1 | FileCheck %s
-! RUN: %flang_fc1 -emit-hlfir -fopenmp -o - %s 2>&1 | FileCheck %s
+! RUN: bbc -emit-hlfir -fopenmp -o - %s 2>&1 | FileCheck %s --check-prefix=CPU
+! RUN: %flang_fc1 -emit-hlfir -fopenmp -o - %s 2>&1 | FileCheck %s --check-prefix=CPU
+
+! RUN: bbc -emit-hlfir -fopenmp -fopenmp-is-target-device -fopenmp-is-gpu -o - %s 2>&1 | FileCheck %s --check-prefix=GPU
+! RUN: %flang_fc1 -triple amdgcn-amd-amdhsa -emit-hlfir -fopenmp -fopenmp-is-target-device -o - %s 2>&1 | FileCheck %s --check-prefix=GPU
program reduce
integer, dimension(3) :: i = 0
@@ -13,81 +16,88 @@ program reduce
print *,i
end program
-! CHECK-LABEL: omp.declare_reduction @add_reduction_byref_box_3xi32 : !fir.ref<!fir.box<!fir.array<3xi32>>> alloc {
-! CHECK: %[[VAL_8:.*]] = fir.alloca !fir.box<!fir.array<3xi32>>
-! CHECK: omp.yield(%[[VAL_8]] : !fir.ref<!fir.box<!fir.array<3xi32>>>)
-! CHECK-LABEL: } init {
-! CHECK: ^bb0(%[[VAL_0:.*]]: !fir.ref<!fir.box<!fir.array<3xi32>>>, %[[ALLOC:.*]]: !fir.ref<!fir.box<!fir.array<3xi32>>>):
-! CHECK: %[[VAL_2:.*]] = arith.constant 0 : i32
-! CHECK: %[[VAL_3:.*]] = fir.load %[[VAL_0]] : !fir.ref<!fir.box<!fir.array<3xi32>>>
-! CHECK: %[[VAL_4:.*]] = arith.constant 3 : index
-! CHECK: %[[VAL_5:.*]] = fir.shape %[[VAL_4]] : (index) -> !fir.shape<1>
-! CHECK: %[[VAL_1:.*]] = fir.allocmem !fir.array<3xi32> {bindc_name = ".tmp", uniq_name = ""}
-! CHECK: %[[VAL_6:.*]]:2 = hlfir.declare %[[VAL_1]](%[[VAL_5]]) {uniq_name = ".tmp"} : (!fir.heap<!fir.array<3xi32>>,
-! CHECK: %[[TRUE:.*]] = arith.constant true
+! CPU-LABEL: omp.declare_reduction @add_reduction_byref_box_3xi32 : !fir.ref<!fir.box<!fir.array<3xi32>>> alloc {
+! CPU: %[[VAL_8:.*]] = fir.alloca !fir.box<!fir.array<3xi32>>
+! CPU: omp.yield(%[[VAL_8]] : !fir.ref<!fir.box<!fir.array<3xi32>>>)
+! CPU-LABEL: } init {
+! CPU: ^bb0(%[[VAL_0:.*]]: !fir.ref<!fir.box<!fir.array<3xi32>>>, %[[ALLOC:.*]]: !fir.ref<!fir.box<!fir.array<3xi32>>>):
+! CPU: %[[VAL_2:.*]] = arith.constant 0 : i32
+! CPU: %[[VAL_3:.*]] = fir.load %[[VAL_0]] : !fir.ref<!fir.box<!fir.array<3xi32>>>
+! CPU: %[[VAL_4:.*]] = arith.constant 3 : index
+! CPU: %[[VAL_5:.*]] = fir.shape %[[VAL_4]] : (index) -> !fir.shape<1>
+! CPU: %[[VAL_1:.*]] = fir.allocmem !fir.array<3xi32> {bindc_name = ".tmp", uniq_name = ""}
+! CPU: %[[VAL_6:.*]]:2 = hlfir.declare %[[VAL_1]](%[[VAL_5]]) {uniq_name = ".tmp"} : (!fir.heap<!fir.array<3xi32>>,
+! CPU: %[[TRUE:.*]] = arith.constant true
!fir.shape<1>) -> (!fir.heap<!fir.array<3xi32>>, !fir.heap<!fir.array<3xi32>>)
-! CHECK: %[[C0:.*]] = arith.constant 0 : index
-! CHECK: %[[DIMS:.*]]:3 = fir.box_dims %[[VAL_3]], %[[C0]] : (!fir.box<!fir.array<3xi32>>, index) -> (index, index, index)
-! CHECK: %[[SHIFT:.*]] = fir.shape_shift %[[DIMS]]#0, %[[DIMS]]#1 : (index, index) -> !fir.shapeshift<1>
-! CHECK: %[[VAL_7:.*]] = fir.embox %[[VAL_6]]#0(%[[SHIFT]]) : (!fir.heap<!fir.array<3xi32>>, !fir.shapeshift<1>) -> !fir.box<!fir.array<3xi32>>
-! CHECK: hlfir.assign %[[VAL_2]] to %[[VAL_7]] : i32, !fir.box<!fir.array<3xi32>>
-! CHECK: fir.store %[[VAL_7]] to %[[ALLOC]] : !fir.ref<!fir.box<!fir.array<3xi32>>>
-! CHECK: omp.yield(%[[ALLOC]] : !fir.ref<!fir.box<!fir.array<3xi32>>>)
-! CHECK: } combiner {
-! CHECK: ^bb0(%[[VAL_0:.*]]: !fir.ref<!fir.box<!fir.array<3xi32>>>, %[[VAL_1:.*]]: !fir.ref<!fir.box<!fir.array<3xi32>>>):
-! CHECK: %[[VAL_2:.*]] = fir.load %[[VAL_0]] : !fir.ref<!fir.box<!fir.array<3xi32>>>
-! CHECK: %[[VAL_3:.*]] = fir.load %[[VAL_1]] : !fir.ref<!fir.box<!fir.array<3xi32>>>
-! CHECK: %[[C1:.*]] = arith.constant 1 : index
-! CHECK: %[[C3:.*]] = arith.constant 3 : index
-! CHECK: %[[SHAPE_SHIFT:.*]] = fir.shape_shift %[[C1]], %[[C3]] : (index, index) -> !fir.shapeshift<1>
-! CHECK: %[[C1_0:.*]] = arith.constant 1 : index
-! CHECK: fir.do_loop %[[VAL_8:.*]] = %[[C1_0]] to %[[C3]] step %[[C1_0]] unordered {
-! CHECK: %[[VAL_9:.*]] = fir.array_coor %[[VAL_2]](%[[SHAPE_SHIFT]]) %[[VAL_8]] : (!fir.box<!fir.array<3xi32>>, !fir.shapeshift<1>, index) -> !fir.ref<i32>
-! CHECK: %[[VAL_10:.*]] = fir.array_coor %[[VAL_3]](%[[SHAPE_SHIFT]]) %[[VAL_8]] : (!fir.box<!fir.array<3xi32>>, !fir.shapeshift<1>, index) -> !fir.ref<i32>
-! CHECK: %[[VAL_11:.*]] = fir.load %[[VAL_9]] : !fir.ref<i32>
-! CHECK: %[[VAL_12:.*]] = fir.load %[[VAL_10]] : !fir.ref<i32>
-! CHECK: %[[VAL_13:.*]] = arith.addi %[[VAL_11]], %[[VAL_12]] : i32
-! CHECK: fir.store %[[VAL_13]] to %[[VAL_9]] : !fir.ref<i32>
-! CHECK: }
-! CHECK: omp.yield(%[[VAL_0]] : !fir.ref<!fir.box<!fir.array<3xi32>>>)
-! CHECK: } cleanup {
-! CHECK: ^bb0(%[[VAL_0:.*]]: !fir.ref<!fir.box<!fir.array<3xi32>>>):
-! CHECK: %[[VAL_1:.*]] = fir.load %[[VAL_0]] : !fir.ref<!fir.box<!fir.array<3xi32>>>
-! CHECK: %[[VAL_2:.*]] = fir.box_addr %[[VAL_1]] : (!fir.box<!fir.array<3xi32>>) -> !fir.ref<!fir.array<3xi32>>
-! CHECK: %[[VAL_3:.*]] = fir.convert %[[VAL_2]] : (!fir.ref<!fir.array<3xi32>>) -> i64
-! CHECK: %[[VAL_4:.*]] = arith.constant 0 : i64
-! CHECK: %[[VAL_5:.*]] = arith.cmpi ne, %[[VAL_3]], %[[VAL_4]] : i64
-! CHECK: fir.if %[[VAL_5]] {
-! CHECK: %[[VAL_6:.*]] = fir.convert %[[VAL_2]] : (!fir.ref<!fir.array<3xi32>>) -> !fir.heap<!fir.array<3xi32>>
-! CHECK: fir.freemem %[[VAL_6]] : !fir.heap<!fir.array<3xi32>>
-! CHECK: }
-! CHECK: omp.yield
-! CHECK: }
+! CPU: %[[C0:.*]] = arith.constant 0 : index
+! CPU: %[[DIMS:.*]]:3 = fir.box_dims %[[VAL_3]], %[[C0]] : (!fir.box<!fir.array<3xi32>>, index) -> (index, index, index)
+! CPU: %[[SHIFT:.*]] = fir.shape_shift %[[DIMS]]#0, %[[DIMS]]#1 : (index, index) -> !fir.shapeshift<1>
+! CPU: %[[VAL_7:.*]] = fir.embox %[[VAL_6]]#0(%[[SHIFT]]) : (!fir.heap<!fir.array<3xi32>>, !fir.shapeshift<1>) -> !fir.box<!fir.array<3xi32>>
+! CPU: hlfir.assign %[[VAL_2]] to %[[VAL_7]] : i32, !fir.box<!fir.array<3xi32>>
+! CPU: fir.store %[[VAL_7]] to %[[ALLOC]] : !fir.ref<!fir.box<!fir.array<3xi32>>>
+! CPU: omp.yield(%[[ALLOC]] : !fir.ref<!fir.box<!fir.array<3xi32>>>)
+! CPU: } combiner {
+! CPU: ^bb0(%[[VAL_0:.*]]: !fir.ref<!fir.box<!fir.array<3xi32>>>, %[[VAL_1:.*]]: !fir.ref<!fir.box<!fir.array<3xi32>>>):
+! CPU: %[[VAL_2:.*]] = fir.load %[[VAL_0]] : !fir.ref<!fir.box<!fir.array<3xi32>>>
+! CPU: %[[VAL_3:.*]] = fir.load %[[VAL_1]] : !fir.ref<!fir.box<!fir.array<3xi32>>>
+! CPU: %[[C1:.*]] = arith.constant 1 : index
+! CPU: %[[C3:.*]] = arith.constant 3 : index
+! CPU: %[[SHAPE_SHIFT:.*]] = fir.shape_shift %[[C1]], %[[C3]] : (index, index) -> !fir.shapeshift<1>
+! CPU: %[[C1_0:.*]] = arith.constant 1 : index
+! CPU: fir.do_loop %[[VAL_8:.*]] = %[[C1_0]] to %[[C3]] step %[[C1_0]] unordered {
+! CPU: %[[VAL_9:.*]] = fir.array_coor %[[VAL_2]](%[[SHAPE_SHIFT]]) %[[VAL_8]] : (!fir.box<!fir.array<3xi32>>, !fir.shapeshift<1>, index) -> !fir.ref<i32>
+! CPU: %[[VAL_10:.*]] = fir.array_coor %[[VAL_3]](%[[SHAPE_SHIFT]]) %[[VAL_8]] : (!fir.box<!fir.array<3xi32>>, !fir.shapeshift<1>, index) -> !fir.ref<i32>
+! CPU: %[[VAL_11:.*]] = fir.load %[[VAL_9]] : !fir.ref<i32>
+! CPU: %[[VAL_12:.*]] = fir.load %[[VAL_10]] : !fir.ref<i32>
+! CPU: %[[VAL_13:.*]] = arith.addi %[[VAL_11]], %[[VAL_12]] : i32
+! CPU: fir.store %[[VAL_13]] to %[[VAL_9]] : !fir.ref<i32>
+! CPU: }
+! CPU: omp.yield(%[[VAL_0]] : !fir.ref<!fir.box<!fir.array<3xi32>>>)
+! CPU: } cleanup {
+! CPU: ^bb0(%[[VAL_0:.*]]: !fir.ref<!fir.box<!fir.array<3xi32>>>):
+! CPU: %[[VAL_1:.*]] = fir.load %[[VAL_0]] : !fir.ref<!fir.box<!fir.array<3xi32>>>
+! CPU: %[[VAL_2:.*]] = fir.box_addr %[[VAL_1]] : (!fir.box<!fir.array<3xi32>>) -> !fir.ref<!fir.array<3xi32>>
+! CPU: %[[VAL_3:.*]] = fir.convert %[[VAL_2]] : (!fir.ref<!fir.array<3xi32>>) -> i64
+! CPU: %[[VAL_4:.*]] = arith.constant 0 : i64
+! CPU: %[[VAL_5:.*]] = arith.cmpi ne, %[[VAL_3]], %[[VAL_4]] : i64
+! CPU: fir.if %[[VAL_5]] {
+! CPU: %[[VAL_6:.*]] = fir.convert %[[VAL_2]] : (!fir.ref<!fir.array<3xi32>>) -> !fir.heap<!fir.array<3xi32>>
+! CPU: fir.freemem %[[VAL_6]] : !fir.heap<!fir.array<3xi32>>
+! CPU: }
+! CPU: omp.yield
+! CPU: }
+
+! CPU-LABEL: func.func @_QQmain()
+! CPU: %[[VAL_0:.*]] = fir.address_of(@_QFEi) : !fir.ref<!fir.array<3xi32>>
+! CPU: %[[VAL_1:.*]] = arith.constant 3 : index
+! CPU: %[[VAL_2:.*]] = fir.shape %[[VAL_1]] : (index) -> !fir.shape<1>
+! CPU: %[[VAL_3:.*]]:2 = hlfir.declare %[[VAL_0]](%[[VAL_2]]) {uniq_name = "_QFEi"} : (!fir.ref<!fir.array<3xi32>>, !fir.shape<1>) -> (!fir.ref<!fir.array<3xi32>>, !fir.ref<!fir.array<3xi32>>)
+! CPU: %[[VAL_4:.*]] = fir.embox %[[VAL_3]]#0(%[[VAL_2]]) : (!fir.ref<!fir.array<3xi32>>, !fir.shape<1>) -> !fir.box<!fir.array<3xi32>>
+! CPU: %[[VAL_5:.*]] = fir.alloca !fir.box<!fir.array<3xi32>>
+! CPU: fir.store %[[VAL_4]] to %[[VAL_5]] : !fir.ref<!fir.box<!fir.array<3xi32>>>
+! CPU: omp.parallel reduction(byref @add_reduction_byref_box_3xi32 %[[VAL_5]] -> %[[VAL_6:.*]] : !fir.ref<!fir.box<!fir.array<3xi32>>>) {
+! CPU: %[[VAL_7:.*]]:2 = hlfir.declare %[[VAL_6]] {uniq_name = "_QFEi"} : (!fir.ref<!fir.box<!fir.array<3xi32>>>) -> (!fir.ref<!fir.box<!fir.array<3xi32>>>, !fir.ref<!fir.box<!fir.array<3xi32>>>)
+! CPU: %[[VAL_8:.*]] = arith.constant 1 : i32
+! CPU: %[[VAL_9:.*]] = fir.load %[[VAL_7]]#0 : !fir.ref<!fir.box<!fir.array<3xi32>>>
+! CPU: %[[VAL_10:.*]] = arith.constant 1 : index
+! CPU: %[[VAL_11:.*]] = hlfir.designate %[[VAL_9]] (%[[VAL_10]]) : (!fir.box<!fir.array<3xi32>>, index) -> !fir.ref<i32>
+! CPU: hlfir.assign %[[VAL_8]] to %[[VAL_11]] : i32, !fir.ref<i32>
+! CPU: %[[VAL_12:.*]] = arith.constant 2 : i32
+! CPU: %[[VAL_13:.*]] = fir.load %[[VAL_7]]#0 : !fir.ref<!fir.box<!fir.array<3xi32>>>
+! CPU: %[[VAL_14:.*]] = arith.constant 2 : index
+! CPU: %[[VAL_15:.*]] = hlfir.designate %[[VAL_13]] (%[[VAL_14]]) : (!fir.box<!fir.array<3xi32>>, index) -> !fir.ref<i32>
+! CPU: hlfir.assign %[[VAL_12]] to %[[VAL_15]] : i32, !fir.ref<i32>
+! CPU: %[[VAL_16:.*]] = arith.constant 3 : i32
+! CPU: %[[VAL_17:.*]] = fir.load %[[VAL_7]]#0 : !fir.ref<!fir.box<!fir.array<3xi32>>>
+! CPU: %[[VAL_18:.*]] = arith.constant 3 : index
+! CPU: %[[VAL_19:.*]] = hlfir.designate %[[VAL_17]] (%[[VAL_18]]) : (!fir.box<!fir.array<3xi32>>, index) -> !fir.ref<i32>
+! CPU: hlfir.assign %[[VAL_16]] to %[[VAL_19]] : i32, !fir.ref<i32>
+! CPU: omp.terminator
+! CPU: }
-! CHECK-LABEL: func.func @_QQmain()
-! CHECK: %[[VAL_0:.*]] = fir.address_of(@_QFEi) : !fir.ref<!fir.array<3xi32>>
-! CHECK: %[[VAL_1:.*]] = arith.constant 3 : index
-! CHECK: %[[VAL_2:.*]] = fir.shape %[[VAL_1]] : (index) -> !fir.shape<1>
-! CHECK: %[[VAL_3:.*]]:2 = hlfir.declare %[[VAL_0]](%[[VAL_2]]) {uniq_name = "_QFEi"} : (!fir.ref<!fir.array<3xi32>>, !fir.shape<1>) -> (!fir.ref<!fir.array<3xi32>>, !fir.ref<!fir.array<3xi32>>)
-! CHECK: %[[VAL_4:.*]] = fir.embox %[[VAL_3]]#0(%[[VAL_2]]) : (!fir.ref<!fir.array<3xi32>>, !fir.shape<1>) -> !fir.box<!fir.array<3xi32>>
-! CHECK: %[[VAL_5:.*]] = fir.alloca !fir.box<!fir.array<3xi32>>
-! CHECK: fir.store %[[VAL_4]] to %[[VAL_5]] : !fir.ref<!fir.box<!fir.array<3xi32>>>
-! CHECK: omp.parallel reduction(byref @add_reduction_byref_box_3xi32 %[[VAL_5]] -> %[[VAL_6:.*]] : !fir.ref<!fir.box<!fir.array<3xi32>>>) {
-! CHECK: %[[VAL_7:.*]]:2 = hlfir.declare %[[VAL_6]] {uniq_name = "_QFEi"} : (!fir.ref<!fir.box<!fir.array<3xi32>>>) -> (!fir.ref<!fir.box<!fir.array<3xi32>>>, !fir.ref<!fir.box<!fir.array<3xi32>>>)
-! CHECK: %[[VAL_8:.*]] = arith.constant 1 : i32
-! CHECK: %[[VAL_9:.*]] = fir.load %[[VAL_7]]#0 : !fir.ref<!fir.box<!fir.array<3xi32>>>
-! CHECK: %[[VAL_10:.*]] = arith.constant 1 : index
-! CHECK: %[[VAL_11:.*]] = hlfir.designate %[[VAL_9]] (%[[VAL_10]]) : (!fir.box<!fir.array<3xi32>>, index) -> !fir.ref<i32>
-! CHECK: hlfir.assign %[[VAL_8]] to %[[VAL_11]] : i32, !fir.ref<i32>
-! CHECK: %[[VAL_12:.*]] = arith.constant 2 : i32
-! CHECK: %[[VAL_13:.*]] = fir.load %[[VAL_7]]#0 : !fir.ref<!fir.box<!fir.array<3xi32>>>
-! CHECK: %[[VAL_14:.*]] = arith.constant 2 : index
-! CHECK: %[[VAL_15:.*]] = hlfir.designate %[[VAL_13]] (%[[VAL_14]]) : (!fir.box<!fir.array<3xi32>>, index) -> !fir.ref<i32>
-! CHECK: hlfir.assign %[[VAL_12]] to %[[VAL_15]] : i32, !fir.ref<i32>
-! CHECK: %[[VAL_16:.*]] = arith.constant 3 : i32
-! CHECK: %[[VAL_17:.*]] = fir.load %[[VAL_7]]#0 : !fir.ref<!fir.box<!fir.array<3xi32>>>
-! CHECK: %[[VAL_18:.*]] = arith.constant 3 : index
-! CHECK: %[[VAL_19:.*]] = hlfir.designate %[[VAL_17]] (%[[VAL_18]]) : (!fir.box<!fir.array<3xi32>>, index) -> !fir.ref<i32>
-! CHECK: hlfir.assign %[[VAL_16]] to %[[VAL_19]] : i32, !fir.ref<i32>
-! CHECK: omp.terminator
-! CHECK: }
+! GPU: omp.declare_reduction {{.*}} alloc {
+! GPU: } init {
+! GPU-NOT: fir.allocmem {{.*}} {bindc_name = ".tmp", {{.*}}}
+! GPU: fir.alloca {{.*}} {bindc_name = ".tmp"}
+! GPU: } combiner {
+! GPU: }
>From c3777c9566273740206705d1c91262eca9995e02 Mon Sep 17 00:00:00 2001
From: ergawy <kareem.ergawy at amd.com>
Date: Wed, 2 Jul 2025 23:29:23 -0500
Subject: [PATCH 2/2] add todo
---
.../LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp b/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp
index 7b07243c5f843..a55239ba1f28f 100644
--- a/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp
@@ -1291,6 +1291,11 @@ initReductionVars(OP op, ArrayRef<BlockArgument> reductionArgs,
mapInitializationArgs(op, moduleTranslation, reductionDecls,
reductionVariableMap, i);
+ // TODO In some cases (specially on the GPU), the init regions may
+ // contains stack alloctaions. If the region is inlined in a loop, this is
+ // problematic. Instead of just inlining the region, handle allocations by
+ // hoisting fixed length allocations to the function entry and using
+ // stacksave and restore for variable length ones.
if (failed(inlineConvertOmpRegions(reductionDecls[i].getInitializerRegion(),
"omp.reduction.neutral", builder,
moduleTranslation, &phis)))
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