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[llvm][mlir][OpenMP] Support translation for linear clause in omp.wsloop and omp.simd #139386

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[llvm][mlir][OpenMP] Support translation for linear clause in omp.wsloop and omp.simd #139386

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fe6a28b
[llvm][mlir][OpenMP] Support translation for linear clause in omp.wsl…
NimishMishra Nov 2, 2025
4804758
Fix wording in testing
NimishMishra Nov 2, 2025
6c5c5d6
Fix CI failure
NimishMishra Nov 2, 2025
597464b
Remove std::move
NimishMishra Nov 2, 2025
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5 changes: 5 additions & 0 deletions flang/lib/Lower/OpenMP/ClauseProcessor.cpp
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Expand Up @@ -1175,11 +1175,16 @@ bool ClauseProcessor::processLinear(mlir::omp::LinearClauseOps &result) const {
omp::clause::Linear>([&](const omp::clause::Linear &clause,
const parser::CharBlock &) {
auto &objects = std::get<omp::ObjectList>(clause.t);
std::vector<mlir::Attribute> typeAttrs;
for (const omp::Object &object : objects) {
semantics::Symbol *sym = object.sym();
const mlir::Value variable = converter.getSymbolAddress(*sym);
result.linearVars.push_back(variable);
mlir::Type ty = converter.genType(*sym);
typeAttrs.push_back(mlir::TypeAttr::get(ty));
}
result.linearVarTypes =
std::move(mlir::ArrayAttr::get(&converter.getMLIRContext(), typeAttrs));
if (objects.size()) {
if (auto &mod =
std::get<std::optional<omp::clause::Linear::StepComplexModifier>>(
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7 changes: 3 additions & 4 deletions flang/lib/Lower/OpenMP/OpenMP.cpp
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Expand Up @@ -1637,8 +1637,7 @@ static void genSimdClauses(
cp.processReduction(loc, clauseOps, reductionSyms);
cp.processSafelen(clauseOps);
cp.processSimdlen(clauseOps);

cp.processTODO<clause::Linear>(loc, llvm::omp::Directive::OMPD_simd);
cp.processLinear(clauseOps);
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@tblah tblah Jul 9, 2025

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The current implementation of processLinear does not seem to guarantee that the variable comes from an alloca. For example what if it is a function argument?
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@NimishMishra NimishMishra Jul 10, 2025

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I ran some tests, and the semantic checks were able to catch those cases. For instance, if the linear variable is anything other than an integer type, we get a semantic error noting that a linear variable with the REF modifier needs to be of integer type.

Do you think we should nevertheless add a check during FIR gen? I added a check during the translation but skipped adding it during FIR gen because of this reason.
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@tblah tblah Jul 10, 2025

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subroutine test(lin, lb, ub, step) integer :: lin, lb, ub, step, i !$omp do linear(lin) do i = lb,ub,step l = l + 2 enddo endsubroutine
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@NimishMishra NimishMishra Jul 24, 2025

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Thanks. I was relooking at the implementation while working on #150386. Given a linear variable, I essentially need its type to allocate similarly typed linear-result variable (that will have linear semantics). Is there any other way to extract the type of variables in the IRBuilder, other than casting to AllocaInst and then retrieving the allocated type?

That would remove the current requirement and allow our implementation to work on the test case you have provided here.
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@tblah tblah Jul 24, 2025

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There is not a way to get the type pointed to in LLVMIR because pointers are untyped (all void *). I guess what we could do would be to add attributes to the linear clause containing the types?
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@NimishMishra NimishMishra Nov 2, 2025

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Sorry for the long absence. I was caught up with some assignments.

The latest version of the PR now handles types by passing them as attributes, which are then used to instantiate the linear variables. Your example above no longer crashes with this implementation.
}

static void genSingleClauses(lower::AbstractConverter &converter,
Expand Down Expand Up @@ -1828,9 +1827,9 @@ static void genWsloopClauses(
cp.processOrdered(clauseOps);
cp.processReduction(loc, clauseOps, reductionSyms);
cp.processSchedule(stmtCtx, clauseOps);
cp.processLinear(clauseOps);

cp.processTODO<clause::Allocate, clause::Linear>(
loc, llvm::omp::Directive::OMPD_do);
cp.processTODO<clause::Allocate>(loc, llvm::omp::Directive::OMPD_do);
}

//===----------------------------------------------------------------------===//
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14 changes: 0 additions & 14 deletions flang/test/Lower/OpenMP/Todo/omp-do-simd-linear.f90
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57 changes: 57 additions & 0 deletions flang/test/Lower/OpenMP/simd-linear.f90
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@@ -0,0 +1,57 @@
! This test checks lowering of OpenMP DO Directive (Worksharing)
! with linear clause

! RUN: %flang_fc1 -fopenmp -emit-hlfir %s -o - 2>&1 | FileCheck %s

!CHECK: %[[X_alloca:.*]] = fir.alloca i32 {bindc_name = "x", uniq_name = "_QFsimple_linearEx"}
!CHECK: %[[X:.*]]:2 = hlfir.declare %[[X_alloca]] {uniq_name = "_QFsimple_linearEx"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
!CHECK: %[[const:.*]] = arith.constant 1 : i32
subroutine simple_linear
implicit none
integer :: x, y, i
!CHECK: omp.simd linear(%[[X]]#0 = %[[const]] : !fir.ref<i32>) {{.*}}
!$omp simd linear(x)
!CHECK: %[[LOAD:.*]] = fir.load %[[X]]#0 : !fir.ref<i32>
!CHECK: %[[const:.*]] = arith.constant 2 : i32
!CHECK: %[[RESULT:.*]] = arith.addi %[[LOAD]], %[[const]] : i32
do i = 1, 10
y = x + 2
end do
!CHECK: } {linear_var_types = [i32]}
end subroutine


!CHECK: %[[X_alloca:.*]] = fir.alloca i32 {bindc_name = "x", uniq_name = "_QFlinear_stepEx"}
!CHECK: %[[X:.*]]:2 = hlfir.declare %[[X_alloca]] {uniq_name = "_QFlinear_stepEx"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
subroutine linear_step
implicit none
integer :: x, y, i
!CHECK: %[[const:.*]] = arith.constant 4 : i32
!CHECK: omp.simd linear(%[[X]]#0 = %[[const]] : !fir.ref<i32>) {{.*}}
!$omp simd linear(x:4)
!CHECK: %[[LOAD:.*]] = fir.load %[[X]]#0 : !fir.ref<i32>
!CHECK: %[[const:.*]] = arith.constant 2 : i32
!CHECK: %[[RESULT:.*]] = arith.addi %[[LOAD]], %[[const]] : i32
do i = 1, 10
y = x + 2
end do
!CHECK: } {linear_var_types = [i32]}
end subroutine

!CHECK: %[[A_alloca:.*]] = fir.alloca i32 {bindc_name = "a", uniq_name = "_QFlinear_exprEa"}
!CHECK: %[[A:.*]]:2 = hlfir.declare %[[A_alloca]] {uniq_name = "_QFlinear_exprEa"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
!CHECK: %[[X_alloca:.*]] = fir.alloca i32 {bindc_name = "x", uniq_name = "_QFlinear_exprEx"}
!CHECK: %[[X:.*]]:2 = hlfir.declare %[[X_alloca]] {uniq_name = "_QFlinear_exprEx"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
subroutine linear_expr
implicit none
integer :: x, y, i, a
!CHECK: %[[LOAD_A:.*]] = fir.load %[[A]]#0 : !fir.ref<i32>
!CHECK: %[[const:.*]] = arith.constant 4 : i32
!CHECK: %[[LINEAR_EXPR:.*]] = arith.addi %[[LOAD_A]], %[[const]] : i32
!CHECK: omp.simd linear(%[[X]]#0 = %[[LINEAR_EXPR]] : !fir.ref<i32>) {{.*}}
!$omp simd linear(x:a+4)
do i = 1, 10
y = x + 2
end do
!CHECK: } {linear_var_types = [i32]}
end subroutine
60 changes: 60 additions & 0 deletions flang/test/Lower/OpenMP/wsloop-linear.f90
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@@ -0,0 +1,60 @@
! This test checks lowering of OpenMP DO Directive (Worksharing)
! with linear clause

! RUN: %flang_fc1 -fopenmp -emit-hlfir %s -o - 2>&1 | FileCheck %s

!CHECK: %[[X_alloca:.*]] = fir.alloca i32 {bindc_name = "x", uniq_name = "_QFsimple_linearEx"}
!CHECK: %[[X:.*]]:2 = hlfir.declare %[[X_alloca]] {uniq_name = "_QFsimple_linearEx"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
!CHECK: %[[const:.*]] = arith.constant 1 : i32
subroutine simple_linear
implicit none
integer :: x, y, i
!CHECK: omp.wsloop linear(%[[X]]#0 = %[[const]] : !fir.ref<i32>) {{.*}}
!$omp do linear(x)
!CHECK: %[[LOAD:.*]] = fir.load %[[X]]#0 : !fir.ref<i32>
!CHECK: %[[const:.*]] = arith.constant 2 : i32
!CHECK: %[[RESULT:.*]] = arith.addi %[[LOAD]], %[[const]] : i32
do i = 1, 10
y = x + 2
end do
!$omp end do
!CHECK: } {linear_var_types = [i32]}
end subroutine


!CHECK: %[[X_alloca:.*]] = fir.alloca i32 {bindc_name = "x", uniq_name = "_QFlinear_stepEx"}
!CHECK: %[[X:.*]]:2 = hlfir.declare %[[X_alloca]] {uniq_name = "_QFlinear_stepEx"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
subroutine linear_step
implicit none
integer :: x, y, i
!CHECK: %[[const:.*]] = arith.constant 4 : i32
!CHECK: omp.wsloop linear(%[[X]]#0 = %[[const]] : !fir.ref<i32>) {{.*}}
!$omp do linear(x:4)
!CHECK: %[[LOAD:.*]] = fir.load %[[X]]#0 : !fir.ref<i32>
!CHECK: %[[const:.*]] = arith.constant 2 : i32
!CHECK: %[[RESULT:.*]] = arith.addi %[[LOAD]], %[[const]] : i32
do i = 1, 10
y = x + 2
end do
!$omp end do
!CHECK: } {linear_var_types = [i32]}
end subroutine

!CHECK: %[[A_alloca:.*]] = fir.alloca i32 {bindc_name = "a", uniq_name = "_QFlinear_exprEa"}
!CHECK: %[[A:.*]]:2 = hlfir.declare %[[A_alloca]] {uniq_name = "_QFlinear_exprEa"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
!CHECK: %[[X_alloca:.*]] = fir.alloca i32 {bindc_name = "x", uniq_name = "_QFlinear_exprEx"}
!CHECK: %[[X:.*]]:2 = hlfir.declare %[[X_alloca]] {uniq_name = "_QFlinear_exprEx"} : (!fir.ref<i32>) -> (!fir.ref<i32>, !fir.ref<i32>)
subroutine linear_expr
implicit none
integer :: x, y, i, a
!CHECK: %[[LOAD_A:.*]] = fir.load %[[A]]#0 : !fir.ref<i32>
!CHECK: %[[const:.*]] = arith.constant 4 : i32
!CHECK: %[[LINEAR_EXPR:.*]] = arith.addi %[[LOAD_A]], %[[const]] : i32
!CHECK: omp.wsloop linear(%[[X]]#0 = %[[LINEAR_EXPR]] : !fir.ref<i32>) {{.*}}
!$omp do linear(x:a+4)
do i = 1, 10
y = x + 2
end do
!$omp end do
!CHECK: } {linear_var_types = [i32]}
end subroutine
8 changes: 4 additions & 4 deletions mlir/include/mlir/Dialect/OpenMP/OpenMPClauses.td
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Expand Up @@ -21,6 +21,7 @@

include "mlir/Dialect/OpenMP/OpenMPOpBase.td"
include "mlir/IR/SymbolInterfaces.td"
include "mlir/IR/BuiltinAttributes.td"

//===----------------------------------------------------------------------===//
// V5.2: [6.3] `align` clause
Expand Down Expand Up @@ -723,10 +724,9 @@ class OpenMP_LinearClauseSkip<
bit description = false, bit extraClassDeclaration = false
> : OpenMP_Clause<traits, arguments, assemblyFormat, description,
extraClassDeclaration> {
let arguments = (ins
Variadic<AnyType>:$linear_vars,
Variadic<I32>:$linear_step_vars
);
let arguments = (ins Variadic<AnyType>:$linear_vars,
Variadic<I32>:$linear_step_vars,
OptionalAttr<ArrayAttr>:$linear_var_types);

let optAssemblyFormat = [{
`linear` `(`
Expand Down
26 changes: 13 additions & 13 deletions mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp
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Expand Up @@ -2824,6 +2824,7 @@ void WsloopOp::build(OpBuilder &builder, OperationState &state,
ArrayRef<NamedAttribute> attributes) {
build(builder, state, /*allocate_vars=*/{}, /*allocator_vars=*/{},
/*linear_vars=*/ValueRange(), /*linear_step_vars=*/ValueRange(),
/*linear_var_types*/ nullptr,
/*nowait=*/false, /*order=*/nullptr, /*order_mod=*/nullptr,
/*ordered=*/nullptr, /*private_vars=*/{}, /*private_syms=*/nullptr,
/*private_needs_barrier=*/false,
Expand All @@ -2842,8 +2843,8 @@ void WsloopOp::build(OpBuilder &builder, OperationState &state,
WsloopOp::build(
builder, state,
/*allocate_vars=*/{}, /*allocator_vars=*/{}, clauses.linearVars,
clauses.linearStepVars, clauses.nowait, clauses.order, clauses.orderMod,
clauses.ordered, clauses.privateVars,
clauses.linearStepVars, clauses.linearVarTypes, clauses.nowait,
clauses.order, clauses.orderMod, clauses.ordered, clauses.privateVars,
makeArrayAttr(ctx, clauses.privateSyms), clauses.privateNeedsBarrier,
clauses.reductionMod, clauses.reductionVars,
makeDenseBoolArrayAttr(ctx, clauses.reductionByref),
Expand Down Expand Up @@ -2888,17 +2889,16 @@ LogicalResult WsloopOp::verifyRegions() {
void SimdOp::build(OpBuilder &builder, OperationState &state,
const SimdOperands &clauses) {
MLIRContext *ctx = builder.getContext();
// TODO Store clauses in op: linearVars, linearStepVars
SimdOp::build(builder, state, clauses.alignedVars,
makeArrayAttr(ctx, clauses.alignments), clauses.ifExpr,
/*linear_vars=*/{}, /*linear_step_vars=*/{},
clauses.nontemporalVars, clauses.order, clauses.orderMod,
clauses.privateVars, makeArrayAttr(ctx, clauses.privateSyms),
clauses.privateNeedsBarrier, clauses.reductionMod,
clauses.reductionVars,
makeDenseBoolArrayAttr(ctx, clauses.reductionByref),
makeArrayAttr(ctx, clauses.reductionSyms), clauses.safelen,
clauses.simdlen);
SimdOp::build(
builder, state, clauses.alignedVars,
makeArrayAttr(ctx, clauses.alignments), clauses.ifExpr,
clauses.linearVars, clauses.linearStepVars, clauses.linearVarTypes,
clauses.nontemporalVars, clauses.order, clauses.orderMod,
clauses.privateVars, makeArrayAttr(ctx, clauses.privateSyms),
clauses.privateNeedsBarrier, clauses.reductionMod, clauses.reductionVars,
makeDenseBoolArrayAttr(ctx, clauses.reductionByref),
makeArrayAttr(ctx, clauses.reductionSyms), clauses.safelen,
clauses.simdlen);
}

LogicalResult SimdOp::verify() {
Expand Down
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