[flang-commits] [flang] [flang][OpenMP] Restore reduction processor behavior broken by #145837 (PR #150178)
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Wed Jul 23 00:28:01 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-flang-openmp
Author: Kareem Ergawy (ergawy)
<details>
<summary>Changes</summary>
Fixes #<!-- -->149089.
Before #<!-- -->145837, when processing a reduction symbol not yet supported by OpenMP lowering, the reduction processor would simply skip filling in the reduction symbols and variables. With #<!-- -->145837, this behvaior was slightly changed because the reduction symbols are populated before invoking the reduction processor (this is more convenient to shared the code with `do concurrent`).
This PR restores the previous behavior.
---
Full diff: https://github.com/llvm/llvm-project/pull/150178.diff
5 Files Affected:
- (modified) flang/include/flang/Lower/Support/ReductionProcessor.h (+1-1)
- (modified) flang/lib/Lower/Bridge.cpp (+2-1)
- (modified) flang/lib/Lower/OpenMP/ClauseProcessor.cpp (+18-14)
- (modified) flang/lib/Lower/Support/ReductionProcessor.cpp (+7-5)
- (added) flang/test/Lower/OpenMP/wsloop-reduction-non-intrinsic.f90 (+25)
``````````diff
diff --git a/flang/include/flang/Lower/Support/ReductionProcessor.h b/flang/include/flang/Lower/Support/ReductionProcessor.h
index 72d8a0096f511..0b49049d43ed2 100644
--- a/flang/include/flang/Lower/Support/ReductionProcessor.h
+++ b/flang/include/flang/Lower/Support/ReductionProcessor.h
@@ -124,7 +124,7 @@ class ReductionProcessor {
/// Creates a reduction declaration and associates it with an OpenMP block
/// directive.
template <typename OpType, typename RedOperatorListTy>
- static void processReductionArguments(
+ static bool processReductionArguments(
mlir::Location currentLocation, lower::AbstractConverter &converter,
const RedOperatorListTy &redOperatorList,
llvm::SmallVectorImpl<mlir::Value> &reductionVars,
diff --git a/flang/lib/Lower/Bridge.cpp b/flang/lib/Lower/Bridge.cpp
index b94833d852b2e..13420f365919d 100644
--- a/flang/lib/Lower/Bridge.cpp
+++ b/flang/lib/Lower/Bridge.cpp
@@ -2125,9 +2125,10 @@ class FirConverter : public Fortran::lower::AbstractConverter {
llvm::SmallVector<mlir::Value> reduceVars;
Fortran::lower::omp::ReductionProcessor rp;
- rp.processReductionArguments<fir::DeclareReductionOp>(
+ bool result = rp.processReductionArguments<fir::DeclareReductionOp>(
toLocation(), *this, info.reduceOperatorList, reduceVars,
reduceVarByRef, reductionDeclSymbols, info.reduceSymList);
+ assert(result && "Failed to process `do concurrent` reductions");
doConcurrentLoopOp.getReduceVarsMutable().assign(reduceVars);
doConcurrentLoopOp.setReduceSymsAttr(
diff --git a/flang/lib/Lower/OpenMP/ClauseProcessor.cpp b/flang/lib/Lower/OpenMP/ClauseProcessor.cpp
index 8b3ad57c53810..594f95ecdda63 100644
--- a/flang/lib/Lower/OpenMP/ClauseProcessor.cpp
+++ b/flang/lib/Lower/OpenMP/ClauseProcessor.cpp
@@ -1116,11 +1116,12 @@ bool ClauseProcessor::processInReduction(
collectReductionSyms(clause, inReductionSyms);
ReductionProcessor rp;
- rp.processReductionArguments<mlir::omp::DeclareReductionOp>(
- currentLocation, converter,
- std::get<typename omp::clause::ReductionOperatorList>(clause.t),
- inReductionVars, inReduceVarByRef, inReductionDeclSymbols,
- inReductionSyms);
+ if (!rp.processReductionArguments<mlir::omp::DeclareReductionOp>(
+ currentLocation, converter,
+ std::get<typename omp::clause::ReductionOperatorList>(clause.t),
+ inReductionVars, inReduceVarByRef, inReductionDeclSymbols,
+ inReductionSyms))
+ inReductionSyms.clear();
// Copy local lists into the output.
llvm::copy(inReductionVars, std::back_inserter(result.inReductionVars));
@@ -1461,10 +1462,12 @@ bool ClauseProcessor::processReduction(
}
ReductionProcessor rp;
- rp.processReductionArguments<mlir::omp::DeclareReductionOp>(
- currentLocation, converter,
- std::get<typename omp::clause::ReductionOperatorList>(clause.t),
- reductionVars, reduceVarByRef, reductionDeclSymbols, reductionSyms);
+ if (!rp.processReductionArguments<mlir::omp::DeclareReductionOp>(
+ currentLocation, converter,
+ std::get<typename omp::clause::ReductionOperatorList>(clause.t),
+ reductionVars, reduceVarByRef, reductionDeclSymbols,
+ reductionSyms))
+ reductionSyms.clear();
// Copy local lists into the output.
llvm::copy(reductionVars, std::back_inserter(result.reductionVars));
llvm::copy(reduceVarByRef, std::back_inserter(result.reductionByref));
@@ -1486,11 +1489,12 @@ bool ClauseProcessor::processTaskReduction(
collectReductionSyms(clause, taskReductionSyms);
ReductionProcessor rp;
- rp.processReductionArguments<mlir::omp::DeclareReductionOp>(
- currentLocation, converter,
- std::get<typename omp::clause::ReductionOperatorList>(clause.t),
- taskReductionVars, taskReduceVarByRef, taskReductionDeclSymbols,
- taskReductionSyms);
+ if (!rp.processReductionArguments<mlir::omp::DeclareReductionOp>(
+ currentLocation, converter,
+ std::get<typename omp::clause::ReductionOperatorList>(clause.t),
+ taskReductionVars, taskReduceVarByRef, taskReductionDeclSymbols,
+ taskReductionSyms))
+ taskReductionSyms.clear();
// Copy local lists into the output.
llvm::copy(taskReductionVars,
std::back_inserter(result.taskReductionVars));
diff --git a/flang/lib/Lower/Support/ReductionProcessor.cpp b/flang/lib/Lower/Support/ReductionProcessor.cpp
index 80c32d066a38d..605a5b6b20b94 100644
--- a/flang/lib/Lower/Support/ReductionProcessor.cpp
+++ b/flang/lib/Lower/Support/ReductionProcessor.cpp
@@ -39,7 +39,7 @@ namespace lower {
namespace omp {
// explicit template declarations
-template void ReductionProcessor::processReductionArguments<
+template bool ReductionProcessor::processReductionArguments<
mlir::omp::DeclareReductionOp, omp::clause::ReductionOperatorList>(
mlir::Location currentLocation, lower::AbstractConverter &converter,
const omp::clause::ReductionOperatorList &redOperatorList,
@@ -48,7 +48,7 @@ template void ReductionProcessor::processReductionArguments<
llvm::SmallVectorImpl<mlir::Attribute> &reductionDeclSymbols,
const llvm::SmallVectorImpl<const semantics::Symbol *> &reductionSymbols);
-template void ReductionProcessor::processReductionArguments<
+template bool ReductionProcessor::processReductionArguments<
fir::DeclareReductionOp, llvm::SmallVector<fir::ReduceOperationEnum>>(
mlir::Location currentLocation, lower::AbstractConverter &converter,
const llvm::SmallVector<fir::ReduceOperationEnum> &redOperatorList,
@@ -607,7 +607,7 @@ static bool doReductionByRef(mlir::Value reductionVar) {
}
template <typename OpType, typename RedOperatorListTy>
-void ReductionProcessor::processReductionArguments(
+bool ReductionProcessor::processReductionArguments(
mlir::Location currentLocation, lower::AbstractConverter &converter,
const RedOperatorListTy &redOperatorList,
llvm::SmallVectorImpl<mlir::Value> &reductionVars,
@@ -627,10 +627,10 @@ void ReductionProcessor::processReductionArguments(
std::get_if<omp::clause::ProcedureDesignator>(&redOperator.u)) {
if (!ReductionProcessor::supportedIntrinsicProcReduction(
*reductionIntrinsic)) {
- return;
+ return false;
}
} else {
- return;
+ return false;
}
}
}
@@ -765,6 +765,8 @@ void ReductionProcessor::processReductionArguments(
if (isDoConcurrent)
builder.restoreInsertionPoint(dcIP);
+
+ return true;
}
const semantics::SourceName
diff --git a/flang/test/Lower/OpenMP/wsloop-reduction-non-intrinsic.f90 b/flang/test/Lower/OpenMP/wsloop-reduction-non-intrinsic.f90
new file mode 100644
index 0000000000000..70b2ae1111a50
--- /dev/null
+++ b/flang/test/Lower/OpenMP/wsloop-reduction-non-intrinsic.f90
@@ -0,0 +1,25 @@
+! Tests reduction processor behavior when a reduction symbol is not supported.
+
+! RUN: %flang_fc1 -emit-hlfir -fopenmp -o - %s 2>&1 | FileCheck %s
+
+subroutine foo
+ implicit none
+ integer :: k, i
+
+ interface max
+ function max(m1,m2)
+ integer :: m1, m2
+ end function
+ end interface
+
+ !$omp do reduction (max: k)
+ do i=1,10
+ end do
+ !$omp end do
+end
+
+! Verify that unsupported reduction is ignored.
+! CHECK: omp.wsloop
+! CHECK-SAME: private(@{{[^[:space:]]+}} %{{[^[:space:]]+}}
+! CHECK-SAME: -> %{{[^[:space:]]+}} : !{{[^[:space:]]+}}) {
+! CHECK: }
``````````
</details>
https://github.com/llvm/llvm-project/pull/150178
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